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RESEARCH ARTICLE
Catalyzing satellite communication: A 20W Ku-
Band RF front-end power amplifier design and
deployment
Jiafa ChenID
1
, Fei Wang
1
*, Dawei Zhang
1¤
, Jinsong Liu
2
, Huaxia Wu
2
, Zhengxian Zhou
3,4
,
Haima Yang
1☯
, Tingzhen Yan
5☯
, Tianchen Tang
1☯
1Department of Research Center of Optical Instrument and System, Ministry of Education and Shanghai Key
Lab of Modern Optical System, University of Shanghai for Science and Technology, Shanghai, China,
2Department of China Aviation East China Optoelectronics, Anhui East China Photoelectric Technology
Research Institute, Wuhu, Anhui Province, China, 3Department of College of Physics and Electronic
Information, Anhui Normal University, Wuhu, Anhui Province, China, 4Department of Optoelectronic
Materials Science and Technology, Anhui Provincial Key Laboratory, Wuhu, Anhui Province, China,
5Department of Printing and pack aging Engineering, Shanghai Publishing and Printing College, Shanghai,
China
☯These authors contributed equally to this work.
¤Current address: Department of Optical-Electrical and Computer Engineering, University of Shanghai for
Science and Technology, Shanghai, China
*feiwang@usst.edu.cn
Abstract
This paper presents a groundbreaking Ku-band 20W RF front-end power amplifier (PA),
designed to address numerous challenges encountered by satellite communication sys-
tems, including those pertaining to stability, linearity, cost, and size. The manuscript com-
mences with an exhaustive discussion of system design and operational principles,
emphasizing the intricacies of low-noise amplification, and incorporating key considerations
such as noise factors, stability analysis, gain, and gain flatness. Subsequently, an in-depth
study is conducted on various components of the RF chain, including the pre-amplification
module, driver-amplification module, and final-stage amplification module. The holistic
design extends to the inclusion of the display and control unit, featuring the power-control
module, monitoring module, and overall layout design of the PA. It is meticulously tailored to
meet the specific demands of satellite communication. Following this, a thorough explora-
tion of electromagnetic simulation and measurement results ensues, providing validation for
the precision and reliability of the proposed design. Finally, the feasibility of that design is
substantiated through systematic system design, prototype production, and exhaustive
experimental testing. It is noteworthy that, in the space-simulation environmental test,
emphasis is placed on the excellent performance of the Star Ku-band PA within the
13.75GHz to 14.5GHz frequency range. Detailed power scan measurements reveal a P
1dB
of 43dBm, maintaining output power flatness < ± 0.5dBm across the entire frequency and
temperature spectrum. Third-order intermodulation scan measurements indicate a third-
order intermodulation of -23dBc. Detailed results of power monitoring demonstrate a
range from +18dBm to +54dBm. Scans of spurious suppression and harmonic suppression,
meanwhile, show that the PA evinces spurious suppression -65dBc and harmonic
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OPEN ACCESS
Citation: Chen J, Wang F, Zhang D, Liu J, Wu H,
Zhou Z, et al. (2024) Catalyzing satellite
communication: A 20W Ku-Band RF front-end
power amplifier design and deployment. PLoS ONE
19(4): e0300616. https://doi.org/10.1371/journal.
pone.0300616
Editor: Mohammad Maktoomi, Virginia Military
Institute, UNITED STATES
Received: September 30, 2023
Accepted: March 3, 2024
Published: April 10, 2024
Copyright: ©2024 Chen et al. This is an open
access article distributed under the terms of the
Creative Commons Attribution License, which
permits unrestricted use, distribution, and
reproduction in any medium, provided the original
author and source are credited.
Data Availability Statement: “A small portion of
the data for the 20W ku-band RF front-end power
amplifier cannot be shared publicly due to a third-
party confidentiality agreement. This data is
available with permission from the Anhui East
China Institute of Optoelectronics Technology and
can be accessed by email through the
organization’s contact person (Hang Fang
ahecopi@126.com or 1833862656@qq.com). All
other data used for this study, including liked
Schematic, Layout, Dimensioned Drawings, are
suppression -60dBc. Rigorous phase-scan measurements exhibit a phase-shift adjust-
ment range of 0˚ to 360˚, with a step of 5.625˚, and a phase-shift accuracy of 0.5dB. Detailed
data from gain-scan measurements show a gain-adjustment range of 0dB to 30dB, with a
gain flatness of ±0.5dB. Attenuation error is 1%. These test parameters perfectly align
with the practical application requirements of the technical specifications. When compared
to existing Ku-band PAs, our design reflects a deeper consideration of specific requirements
in satellite communication, ensuring its outstanding performance and uniqueness. This PA
features good stability, high linearity, low cost, and compact modularity, ensuring continuous
and stable power output. These features position the proposed system as a leader within
the market. Successful orbital deployment not only validates its operational stability; it also
makes a significant contribution to the advancement of China’s satellite PA technology, gen-
erating positive socio-economic benefits.
Introduction
Recently, the deployment of communication satellites in low Earth orbit has emerged as a sig-
nificant global research focus. Additionally, low Earth-orbit satellites, governed by a “first-
come-first-served” rule, represent a renewable and strategic asset, influencing the future devel-
opmental prospects of nations worldwide. Consequently, competition is intense among coun-
tries in the field of near-Earth communication [1–5]. The satellite-based communication
system, characterized by satellite-ground interaction, is extensively used, not only in satellite
communication per se, but also in remote-sensing measurements, and various other fields [6].
The Ku-Band, known for its extended signal-transmission range and robust anti-interference
capability, is widely employed in satellite-based communications [7–11]. The power amplifier
(PA), a critical component in the satellite-based communication system, is primarily employed
for amplifying and transmitting high-power RF signals. Furthermore, its performance and sta-
bility directly influence the overall effectiveness of the communication system [12–16]. There-
fore, the design and implementation of PAs evince immense significance and practical value.
Currently, star-communication technology is advancing rapidly, imposing higher require-
ments, but also offering broader application prospects for RF PA design [17–19]. Researchers
worldwide have extensively investigated RF PA design in the field of satellite communication
[20,21]. Common PA-design models include microwave tubes, semiconductor devices, and
integrated circuits [22–27]. While microwave-tube PAs offer good linearity and stability, they
are larger, consume more power, and incur higher maintenance costs [28,29]. Additionally,
while semiconductor-device PAs entail advantages such as small size and low power consump-
tion, their linearity and stability evince limitations related to device characteristics [30,31].
Thus, improving the reliability and maintenance of the PA, while ensuring power output and
signal stability, is a key focus.
Meanwhile, owing to challenges in current PA research, particularly around modular
design, researchers have proposed various new ideas and approaches, such as the design con-
cept of the combination of discrete and integrated modules. These approaches can enhance
the balance of power amplification, matching, and stability considerations [32–36]. Research
on low-noise techniques and modulation approaches for PAs has also garnered significant
attention [37–40]. Foreign companies, led by STMicroelectronics, have achieved considerable
success in the field of PAs, with their widely used products establishing them as international
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available from the Supporting information
(S1_raw_images).”
Funding: This work was supported by the National
Natural Science Foundation of China
(NO.62205210 to F.W). And The funders had role
in study design, and analysis, preparation of the
manuscript. There was no additional external
funding received for this study.
Competing interests: The authors have declared
that no competing interests exist.
leaders due to their excellent performance. In China, research in this field is also gradually
emerging, although the PAs developed using domestic gallium nitride (GaN) chips currently
manifest low efficiency, low linearity, significant power drops, and poor reliability under con-
tinuous-wave high and low temperature conditions. Meanwhile, all pertinent indices evince
more than 10% difference, and this cannot meet the demand associated with high-power
amplifiers for high-performance satellite communication [41–47]. In the future, the require-
ments of RF PAs will continue to increase, as star technology further advances. Therefore,
improving power-output efficiency, reducing power consumption, increasing reliability, and
reducing noise will become significant topics in future RF PA research. Meanwhile, the devel-
opment of more intelligent control systems, and more accurate simulation and testing tech-
niques, will provide better support for RF PA research [48–50].
This paper addresses the specific requirements of satellite communication by introducing a
modular, low-noise Ku-Band 20W RF transmit front-end PA. The primary objective is to
enhance the quality and reliability of satellite communication, thereby contributing signifi-
cantly to the advancement of satellite-communication technology. Through in-depth research,
and a meticulous analysis of PA circuit principles, system parameters, and component selec-
tion, the system is designed for integration. The integration process leverages innovative, inde-
pendently researched and developed GaN microwave power devices, with a focus on
enhancing power output and linearity. This strategic approach successfully resolves issues
related to poor linearity, low efficiency, and inadequate stability. Furthermore, it establishes a
rational and achievable technical and process implementation plan, permitting the realization
of multi-functional power amplification, high modularity, stable power output, and enhanced
reliability. Ultimately, indeed, this work establishes comprehensive power-amplification tech-
nical indices, applicable to practical engineering projects.
System design and working principle
The Ku-Band satellite transmission signal proposed in this paper is a linearly polarized electro-
magnetic wave, with a specific polarization angle. It is based on the principle of vector signal
synthesis decomposition [51,52]. This allows the decomposition of the phase and amplitude
of the Ku linearly polarized electromagnetic wave into vertical and horizontal linear-polariza-
tion channels. The topology of the 20W RF transmit front-end PA for the Star Ku-Band is
illustrated in Fig 1. The system utilizes spatial combination technology, connecting the display
control unit, comprising a microcontroller (MCU), power-control module, monitoring mod-
ule, and two amplifiers with identical power output. Additionally, it features a modular design,
Fig 1. Topological diagram of 20W RF transmit front-end PA for Star Ku-Band.
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enhancing maintainability and facilitating mass production. This design reduces system losses,
significantly improves output power and efficiency, and increases Ku-Band power amplifica-
tion from 13.75GHz to 14.5GHz. The system has successfully achieved power amplification,
out-of-band filtering, gain adjustment, polarization phase shift, beam phase shift, and the
detector monitoring of Ku-Band RF signals. Simultaneously, it has achieved the tracking and
transmission of Ku-Band satellite-communication signals and power amplification.
Fig 1 illustrates a dual-channel RF link with identical power output. The Ku-Band transmis-
sion signal undergoes initial processing in a preamplifier module, the latter comprising an
attenuator, a CNC phase shifter, a low-noise amplifier, and a filter. This conversion and cor-
rection process permits both horizontal and vertical polarization. Adjustments to the beam
phase shift and the correction of phase shifts between array elements are also realized. Subse-
quently, drive amplification of the transmit signal is achieved through the drive amplifier mod-
ule, which consists of a high linear drive chip and an attenuator. Finally, signal-power
amplification is achieved through the final-stage amplifier module. This module encompasses
an amplifier chip, microstrip-waveguide conversion, isolation filter components, harmonic
component suppression, one-way output, and an improvement of output standing waves. The
power-control module primarily converts the input DC +24V power into different voltages,
ensuring the necessary voltage and current for the RF link and the active chips in the monitor-
ing module. The monitoring module is comprised of an attenuator, phase shifter, temperature
and power monitoring components, and fan control, via the internal MCU chip, completing
chip control. Externally, it can communicate with the beam-control module via the RS232
serial port, providing operational-status parameters. Additionally, it performs interactive con-
trol, internal configuration, monitoring, and module-alarm functions. The main technical
indices of its system design are presented in Table 1.
Low-noise amplification design
The microwave low-noise amplifier is a critical component in radar, electronic countermea-
sures, and telemetry remote-control receiving systems [53,54]. The noise in the transmitting
system is heavily influenced by the noise of the amplifier, with the noise coefficient of the
Table 1. Main technical indices of its system design.
Indicators Technical requirements
Operating frequency (F
0
)13.75GHz—14.5GHz
Input power -10dBm - 0dBm
Peak output power (Psat) 20W
Output power flatness 0.5dBm
Output P
1dB
power 43dBm (single-load continuous wave signal test)
Third order syncopation -23dBc (offset 20MHz dual carrier combined output 38dBm test)
Gain adjustment 0dB-30dB, steps of 0.5dB, gain flatness 2dB, attenuation error 1%
Phase shift regulation 0˚-360˚, steps of 5.625˚, phase shift accuracy of 0.5dB
Stray suppression -65dBc
Harmonic suppression -60dBc
Port standing waves 1.5
Monitoring communication
method
Ethernet port/RS-485
Operating temperature -40˚C ~ -60˚C
Amplifier protection function Over-current, over-excitation, over-reflection, over-temperature and other
protection functions
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preamplifier module exerting the most significant impact on the overall noise of the micro-
wave system. Additionally, its gain determines the extent of noise suppression in the subse-
quent circuit. This highlights the fact that the performance of the low-noise amplifier
constrains the overall performance of the transmitting system. It also significantly contributes
to enhancing the overall technical level of the system [55–58]. Therefore, the fundamental
requirements for low-noise amplifiers include a low-noise figure, sufficient power gain, good
operating stability, and a large dynamic range [59,60].
Noise factor. The noise factor (NF) of a low-noise amplifier serves as a crucial indicator,
encompassing the comprehensive noise performance of the entire receiving front-end system,
and exerting a direct influence on the sensitivity of that system [61]. More precisely, the total
noise factor of a low-noise amplifier is characterized by the ratio of the input signal-to-noise
ratio to the output signal-to-noise ratio. This metric provides valuable insights into the ability
of the amplifier to maintain signal integrity and minimize noise, thereby playing a pivotal role
in optimizing the performance of the receiving front-end system.
�¼Sin=Nin
Sout=Nout ð1Þ
Where, S
in
is the input signal power, N
in
is the input noise power, S
out
is the output signal
power and N
out
is the output noise power.
Sout ¼G1Sin ð2Þ
Nout ¼N1þG1Nin ð3Þ
where N
1
is the noise inherent in the first-stage amplifier, and G
1
is the gain of the first-stage
amplifier, which can be further derived as follows:
�¼Sin=Nin
G1Sin=ðN1þG1Nin Þ¼1þN1
G1Nin ð4Þ
Therefore, the total noise factor of the two-stage cascade amplifier can be derived thus:
�¼Sin=Nin
G1G2Sin=ðN2þN1G2þG1G2Nin Þ¼1þN1
G1Nin þN2
G1G2Nin ¼�1þ�21
G1ð5Þ
G
2
,N
2
are the noise and gain of the second-stage amplifier, respectively. ϕ
1
is the noise fac-
tor of the first stage, and ϕ
1
is the noise factor of the second. The overall noise factor in a cas-
cade configuration is mainly determined by the performance of the first-stage low-noise
amplifier. A smaller noise factor, and larger gain, lead to a reduced overall circuit noise factor.
Subsequent stages must primarily consider gain and power capacity. In the design of input
matching circuits, any passive component, such as resistors, capacitors, and transmission
lines, will directly degrade the overall circuit noise factor, according to this formula. Further-
more, the fundamental principle of input matching design for low-noise amplifiers involves
conjugately matching the optimal noise impedance (Γopt) of the device to 50 ohms, using a
minimal number of passive components. Therefore, we conducted simulations and relevant
tests on the noise factor of the first-stage amplifier. Specific results are presented in Fig 2. This
design concept aims to ensure that the entire system maintains optimal noise performance
during input matching, offering robust support for the efficient operation of the overall
circuit.
Illustrated in Fig 2, the NF typically measures 1.6dB, reflecting favorable noise characteris-
tics. Nonetheless, within the frequency range of 13.75GHz to 14.5GHz, the measured noise
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figure exceeds the simulated value. In practical low-noise design considerations, pursuit of the
lowest noise figure may result in significant port standing wave issues. Particularly when cas-
caded with a transmitting band-pass filter, moreover, the total noise figure may significantly
exceed the theoretically calculated value. This phenomenon, mainly attributable to transmis-
sion-line losses and radiation losses caused by discontinuities, results in a noise figure slightly
lower than the theoretical value, but still in compliance with the technical specifications out-
lined in this paper. In practical applications, finding a balance between the lowest noise figure
and port standing waves is crucial to ensure the reliability and performance of the system, in
accordance with the design specifications.
Stability analysis. If the amplifier enters an unstable state, it may trigger self-oscillation of
the signal, resulting in a rapid change in the amplifier gain and, ultimately, leading to transistor
burnout [24]. Thus, in amplifier design, our objective is to maximize operational stability. In
essence, in fact, our aim is to design an amplifier capable of stable operation under various
impedance conditions, thus avoiding self-oscillation. This design principle aims to guarantee
the reliability of the amplifier, sustaining stable performance across diverse operating condi-
tions to minimize the risk of damage and failure.
K¼1 jS11j2 jS22 j2þ jDj2
2jS12jjS21 j>1ð6Þ
jDj ¼ jS11S22 S12 S21j<1ð7Þ
Fig 2. NF curve.
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Where K is the StabFact of the test process, i.e., the stability coefficient. Λis the reflection coef-
ficient, and S
ij
is the scattering parameter of the two-port network of S. This is mainly used to
judge the stable state of the whole system. When K is greater than 1, it is in a stable state; if K is
less than 1, conversely, it is in an unstable state.
1 jS11j2>jS12 jjS21j ð8Þ
1 jS22j2>jS12 jjS21j ð9Þ
Low-noise amplifiers can achieve absolute stability only when the four inequalities men-
tioned above are satisfied. Hence, in the early design stages, calculations must assess the stabil-
ity of the amplifier. This process simplifies the selection of appropriate transistor types, while
compensating for the real part of the input impedance, using series resistors. Thus, the mainte-
nance of transistor stability requires the real part of the input impedance to be greater than
zero, indicating a reflection coefficient less than 1. In this study, we used matching reactive
components to guarantee amplifier stability. Following completion of the layout design, stabil-
ity coefficient simulations were conducted using ADS, as depicted in Fig 3. This process helps
validate the stability of the design, while offering strong support for subsequent work.
In view of the simulation results, shown in Fig 3, we determined that the StabFact exceeds 1
within the frequency range of 13.75GHz to 14.5GHz. This guarantees the absolute stability of
the amplifier across the frequency band, aligning with the technical specifications of the low-
noise amplifier design in this paper. This result robustly substantiates the calculations and
Fig 3. StabFact curve.
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assessments of amplifier stability in our previous work, establishing a reliable theoretical foun-
dation for achieving optimal performance within a specific frequency range in the designed
system.
Gain and gain flatness. In the design of low-noise amplifier circuits, three power gains
are commonly used: transmission power gain G
t
, operating power gain G
p
, and utilization
power gain G
a
[62]. The relationship between the three power gains is as follows.
Gt¼P1
P2¼P1
Pin
Pin
P2¼GpM1ð10Þ
Gt¼P1
P2¼P1
P3
P3
P2¼GpM2ð11Þ
Where P
1
is the absorbed power of the load; P
in
is the input power; P
2
is the capital-power out-
put from the signal source; P
3
is the capital power absorbed by the load; and M
1
,M
2
are the
mismatch coefficients of the input and output, respectively. When the amplifiers are conjugate
matched, the following is obtained:
M1¼M2ð12Þ
Gt¼Ga¼Gpð13Þ
The gain flatness indicates the fluctuation of the gain, i.e., ΔG=G
max
−G
min
. A consistent
gain flatness is crucial in alleviating challenges in subsequent amplifier designs. To enhance
the credibility of our proposed design, we employed Advanced Design System (ADS) for simu-
lations and conducted pertinent tests on the gain, as illustrated in Fig 4. This rigorous process
ensured that the system maintained uniform gain levels across various frequencies, establish-
ing a stable foundation for overall system performance. The thorough simulation and testing
procedures enabled a comprehensive evaluation of the effectiveness of the proposed solution,
thereby offering compelling support for its practical applications.
In analyzing Fig 4, we may observe that, within the frequency range of 13.75GHz to
14.5GHz, the typical gain of the amplifier is 19dBm, and it maintains a gain flatness of ±0.5dB.
This suggests that the low-noise amplifier excels in terms of gain performance. Nonetheless, a
slight decrease in gain within this frequency band is observed in the test results, compared to
the simulation. The main reason is a minor inaccuracy in the modeling of relevant losses,
resulting in a slightly smaller measured attenuation as compared to the simulation. This result
still aligns with the practical technical specifications of this paper, however.
As indicated by the data in Table 2, the low-noise amplifier designed for this paper exhibits
outstanding comparative performance in terms of noise factor, stability, and gain flatness,
demonstrating significant superiority. These advantages provide excellent prospects for the
design within practical application scenarios. We thus anticipate that our work will contribute
significantly to the enhancement, and broader application, of low-noise amplifiers in the cur-
rent field.
Module design
RF link
Preamplifier module. Fig 5 shows the block diagram for the single-channel preamplifier
module in the RF link of the Ku-Band RF transmit front-end PA, as designed for star applica-
tions. Key components encompass a detector, attenuator, CNC phase shifter, low-noise
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amplifier, and filter. The preamplifier link consolidates functions such as link-gain compensa-
tion, low-noise amplification, amplitude adjustment, over-excitation automatic control, gain
transmission, polarization-phase shift adjustment, and harmonic suppression, into a single
module. Consequently, the module possesses characteristics of high integration, miniaturiza-
tion, and multi-functional fusion.
The module includes four levels of attenuators for both the horizontal and vertical polariza-
tion channels. The first two levels of the attenuation system include a numerical-control atten-
uator and a second-level attenuator. These are controlled in response to external input-gain
numerical-control plus and minus commands, to meet the amplitude requirements of the hor-
izontal and vertical branches of the polarization angle. Furthermore, this facilitates the closed-
loop adjustment of the signal amplitude in the two channels. The second two levels of the
attenuation system consist of a third attenuator and an analog attenuator. The digital phase
shifter in the system module on the horizontal and vertical polarization channels can respond
to external input-phase shift-adjustment commands, achieving a 90˚ orthogonal phase shift of
Table 2. Performance comparison of low-noise amplifiers.
Technical index [63] [64] [65] This work
Freq (GHz) 2–20 4–20 13–16 13.75–14.5
NF (dB) 3.2 1.6 1 1.6
Gain(dB) 18 24 22.8 19
Gain Flatness (dB) ±1±1.25 ±6±0.5
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Fig 4. Gain curve.
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the horizontal and vertical channels. This enhances polarization isolation, thereby improving
the performance simulation of the phase shift. Fig 6 illustrates the primary performance simu-
lation of the phase shift.
As presented in Fig 6, the phase-shift unit can achieve phase adjustment in the range of 0˚-
360˚, with a step size of 5.625˚, and its phase-shifting accuracy is 0.5dB. Additionally, the
phase of the transmission channel for each component in the phased array is compensated
and corrected. The correction value is derived from the offset value of the beam shifter in the
receiving channel and adjusted based on its size. Hence, the configuration value of the phase-
Fig 5. Block diagram of single-channel preamplifier module.
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Fig 6. Phase-shift performance simulation curve.
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shift unit is the sum of the polarization phase-shift parameter 1, and the array element inter-
beam phase-shift parameter 2. This component also includes a low-noise amplifier stage to
achieve a gain amplification of 20dB and a low power output of 7dBm. This is crucial for driv-
ing the driver stage. The principle of the single-channel module for this stage is illustrated in
Fig 7 (Schematic, layout, and dimensional drawings are described in detail in S2, S11, S15, S19,
S24, S25 Figs in S1 Raw images).
As shown in Fig 7, the entire single-channel preamplifier module uses more mature friction
welding, and other process technologies, to sinter the RF link in the module and physically iso-
late it with a special isolation pressure bar, thereby reducing interference. Through rational
arrangement of the circuit structure, the circuit layout can be optimized, improving both the
efficiency and miniaturization of the module. Simultaneously, this accomplishes Ku-band sig-
nal-power adjustment and polarization, beam phase-shift adjustment, vertical and horizontal
polarization conversion and correction, phase-shift correction between array elements, power
amplification, and suppression of harmonics and out-of-band interference signals. Conse-
quently, the preamplifier is characterized by its small size, low power consumption, high reli-
ability, excellent performance, flexible configuration, and high stability.
Drive amplification module. Fig 8 illustrates the block diagram of a single-channel
driver-amplifier module, primarily consisting of a low-noise amplifier, attenuator, driver-
amplifier chip, and isolator. This module accomplishes the transmission and power amplifica-
tion of the RF signal output from the preamplifier module, ensuring the normal operation of
the final amplifier module. The RF signal output from the pre-stage amplifier passes through
the fourth attenuator in this module, thus ensuring satisfaction of the input requirements of
the driver amplifier. Simultaneously, the signal undergoes additional amplification by the low-
noise amplifier. After passing through the fifth and sixth attenuators to address port standing
wave issues, caused by the digital IC chip and low-noise amplifier, the signal is ultimately
Fig 7. Schematic diagram of the preamplifier module.
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Fig 8. Block diagram of drive-amplification module.
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amplified using the linear-driver chip. Moreover, to prevent the reflection of high power from
the final stage back to the driver-amplifier module (which can lead to oscillation and damage
to the driver amplifier), an isolator can be used to separate the driver-amplifier module from
the final-stage amplifier module. The fundamental driver-amplifier module is depicted in
Fig 9 (Schematic, layout, and dimensional drawings are described in detail in S3, S12, S16, S20,
S26, S27 Figs in S1 Raw images).
Given the low output power of the preamplifier and the high output power of the final
amplifier, maintenance of a linear operating state for the driver-amplifier module in between
is crucial. Consequently, to mitigate crossover distortion, we conducted tests on the output
performance of the module, generating its output-performance graph (see Fig 10).
Fig 10(A) shows that the module delivers over 38dBm of output power within the 13.5GHz
to 14.5GHz frequency band. Simultaneously, in Fig 10(B), the graph depicts the modular out-
put power as increasing with input power in the linear operational state, reaching over 34dBm.
Moreover, it achieves a power gain of >28dB with a current draw of <1.7A. The module
exhibits excellent linearity. With operation at P
1dB
, employment of a power-fallback method
results in a 7dB fallback above the threshold, ensuring no further reduction in the linearity
index of the RF link.
Final stage amplification module. The final-stage amplifier module, a crucial component
of the system, is designed to enhance the characteristics of the PA. It plays a key role in ampli-
fying the signal transmitted from the driver-amplifier module, in order to generate a high-
power signal. This module encompasses a GaN chip, microstrip-waveguide converter, detec-
tor, and isolation filter (see Fig 11).
This module aims to utilize 0.25um GaN HEMT process technology, gain compression and
expansion technology, and bias-adaptive dynamic adjustment on gate-voltage technology, in
the domain of high linear continuous-wave amplification. Consequently, it enhances the
autonomous controllable development process of GaN chips. These chips are collaboratively
developed to achieve a high-power Ku-Band amplifier through pre-distortion, efficient spatial
Fig 9. Drive-amplifier module schematic.
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synthesis, and other technologies. Experimental results demonstrate that the chip exhibits
good linearity and high efficiency, meeting the RF output-power technical index requirements
for transmitting front-end power amplification in the Ku-Band for star use.
The microstrip-waveguide transition structure, within the module, transforms the output
signal of the GaN chip into a standard waveguide port, in which harmonic components are
subsequently suppressed by the isolation filter. Furthermore, real-time monitoring of the out-
put-power amplitude is performed by a detector. The final-stage amplifier is saturated to
enhance amplitude consistency between channels. The positive (40W) and reverse (20W) cou-
pling port of the isolation filter facilitates one-way output, ultimately improving the output
standing wave, preventing reverse feed-in, suppressing harmonic components, and ensuring
that the P
1dB
output power meets technical index requirements. See Fig 12 for details (Sche-
matic, layout, and dimensional drawings are described in detail in S6, S13, S21, S28, S29 Figs
in S1 Raw images).
The microstrip-waveguide transition design is crucial within this module, as its performance
directly affects system output power, gain, and other parameters. Therefore, it is crucial for the
transition design to exhibit good standing waves, high reliability, and relative insensitivity to
assembly errors [66–69]. Fig 13 illustrates the relative position relationship between the micro-
strip and the waveguide output port (Detailed description in S32 Fig in S1 Raw images). The
simple and compact transition of the module allows insertion into a section of the transition
Fig 11. Block diagram of the final-stage amplification module.
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Fig 10. Output-performance curve of the driver-amplifier module. (a) Frequency-output power graph (b) Input power-output power/gain/Id graph.
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band. It serves as a coupling probe from the broad side center of the waveguide, facilitating the
coupling of the TE
10
mode in the waveguide to the microstrip. The distance between the transi-
tion band and the short pavement in the rectangular waveguide is approximately one quarter of
a wavelength, positioning it at the strongest electrical field point of the waveguide. Stepped
impedance lines are used to realize the transition band and the microstrip line between the
Fig 12. Schematic diagram of the final-stage amplifier module.
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Fig 13. Schematic diagram of microstrip-translational waveguide transition.
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matching networks. A quartz substrate passes through the rectangular waveguide, providing a
waveguide window and aiding substrate positioning. This forms a sealed structure, enabling
polarization of the rectangular waveguide in different directions.
As demonstrated in the transition diagram, the High Frequency Structure Simulator
(HFSS) can model and optimize parameters with a significant impact on transition perfor-
mance. The structural model is depicted in Fig 14.
Fig 14 illustrates the microstrip-waveguide transition structure, which consists of a metal
cavity housing a planar circuit. To ensure that the cavity exclusively accommodates the TE
10
-
mode coupled planar circuit, optimal model values must be obtained through parameter scan-
ning and optimization, and this primarily impacts transition performance. The key structural
dimensions are as follows: transition-band length and width (d = 4.3mm, Ix = 2mm); match-
ing-band length and width (Wp = 4.3mm, Wx = 2mm). Simulation results based on these
dimensions are displayed in Fig 15.
Fig 15 reveals a return loss better than -20dB within the 13.75GHz to 14.5GHz Ku-Band,
with insertion loss below 0.1dB. This conversion structure exhibits a wide bandwidth, minimal
insertion loss, and low return loss, making it an ideal choice that satisfies the necessary require-
ments. To further validate the microwave performance of the final-stage amplifier module,
gain and standing-wave indicators were measured using a vector network analyzer, after sys-
tem assembly. This procedure is illustrated in Fig 16.
In Fig 16, the gain of the final-stage amplifier module is seen to exceed 26dB within the fre-
quency range of 13.75GHz to 14.5GHz, while the Standing Wave Ratio (SWR) is below 1.2.
These results suggest that the module exhibits favorable linearity and SWR, meeting all the
design requirements for the module.
Fig 14. Simulation model of microstrip-to-waveguide transition.
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Overall design of the display and control unit
Power control module. The power-supply unit incorporates a stable, integrated high-
power DC-DC power-supply module, with a 24V DC input voltage. Initially, an Electro
Fig 15. Simulation curve of microstrip-to-waveguide transition.
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Fig 16. Performance test chart of the final-stage amplification module. (a) Frequency-gain test curve (b) Frequency-SWR test curve.
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Magnetic Interference (EMI) power filter is employed to ensure the EMC test performance of
the entire system. Subsequently, the process is divided into three branches: the MOS tube
switches deliver an output of 24V voltage for amplifier and fan usage, the DC-DC module out-
puts 6.5V voltage for the drive-amplifier chip, and the linear regulator stabilizes 6.5V to pro-
duce 5V and 3.3V voltages for phase shift, attenuation, and usage monitoring. The schematic
block diagram of the power-supply unit is illustrated in Fig 17 (Detailed description in S1-S9,
S14-S16 Figs in S1 Raw images).
The PA module includes a pre-stage low-noise amplifier, and the total power consumption
of the control chip is 1W. The drive PA power consumption is 3W/20% = 15W, and the
final-stage PA power consumption is 90W. The fan power consumption is 15W, and the
DC/DC total efficiency should be 90%. Therefore, the total power consumption of the Ku-
Band PA is 140W.
Monitoring module. The monitoring unit observes and manages the real-time working
status of each module within the device. This unit facilitates remote monitoring, fault identifi-
cation, and safety-protection functions. It also allows monitoring and control of the modular
alarm functions (see Fig 18, Detailed description in S1-S9, S16-S18 Figs in S1 Raw images).
The internal MCU is primarily responsible for monitoring power, phase shifting, attenuation,
and temperature, and for executing other controls (such as fan on/off). Additionally, it con-
ducts external controls through the 74HC595 serial and parallel port conversion, providing
operational status parameters.
Fig 18 displays a schematic diagram, illustrating the three typical functions of the monitor-
ing unit. Power detection is primarily accomplished through the transmitter output, using the
coupler and detector. Simultaneously, the output power and reflected power are converted
into analog voltage and transmitted to the MCU, where the latter assesses the output alarm sig-
nal. The current detection circuit is a well-established one. The overheating alarm depends on
a built-in temperature-monitoring sensor chip, which queries the modular temperature every
five seconds. Real-time monitoring of the system reflects the current operating status, ensuring
the stability and reliability of the entire PA operation.
Complete PA design. With the assistance of special experiments, including prototype
production, environmental verification, and small-batch production, the performance index
of the Ku-Band RF front-end PA for star has been configured to meet all design requirements.
The system conducts module-level synthesis to facilitate amplifier reuse. Moreover, the ratio-
nal design of the entire system ensures the integration of all modules (including RF, power
supply, and monitoring) within a sealed milling cavity. Additionally, over-excitation
Fig 17. Power-supply unit: Schematic block diagram.
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protection, overheating protection, and other control and protection technologies are
employed to enhance amplifier safety, reliability, and maintainability, and to achieve stable
power output. Due to the large power consumption of the overall radar system, heat genera-
tion is a serious concern, and the working environment is more complex. In turn, this gener-
ates heat-dissipation difficulties, which can significantly reduce the life of this PA. Therefore,
enhancement of the heat-dissipation efficiency of the PA is a crucial consideration in the
design of this product. Effective heat-dissipation measures can be implemented to maintain
the thermal balance of the PA. More specifically, to minimize the thermal resistance of the
device, it is secured in the cavity with a maximum contact surface, using screw fastening or
Fig 18. Monitoring-module control schematic.
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load welding, more efficiently to dissipate heat. Nevertheless, to optimize the overall thermal
design, and to achieve efficient heat dissipation, a combination of forced air-cooling and grid-
type heat-sink technology is utilized. This allows the thermal-performance parameter require-
ments to be satisfied. Moreover, this approach also permits the technical index of the entire
PA to be realized, while also keeping cooling costs minimal, and the structure itself compact.
The shape of the PA can be seen in Fig 19 (Detailed description in S1-S32 Figs in S1 Raw
images).
Experimental system
The system test device has been developed according to the actual technical parameters and
product-design specifications of the star. The output power, third-order cross-talking, power
detection, spurious rejection, gain adjustment, harmonic rejection, phase-shift attenuation,
Fig 19. Diagram of the 20W RF transmit front-end PA for star Ku-Band. (a) Forced air-cooling design diagram (b) Grid-type heat-sink design diagram (c)
PA internal layout diagram.
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and other parameters of the PA for the star were tested. The experimental system for these
tests is depicted in Fig 20.
The assembly of the test system is illustrated in Fig 20. Each instrument undergoes indepen-
dent calibration, after which the test parameters are established. In order to ensure the accuracy
of the test, the instruments are powered on and preheated for more than thirty minutes. Next,
the remote-control port is connected and the host computer is opened. The test can then begin.
First, one should connect the attenuation load to the waveguide output port of the ampli-
fier. Connect the spectrum meter or power meter to the output coupling port of the test cou-
pler. Connect the signal source or scalar network analyzer to the amplifier input port, using a
cable or microwave switch. Second, power must be supplied to the amplifier. Thirdly and
finally, connect the equipment to the host computer, thus enabling the sending of commands
to control the operation of the equipment, and to initiate the testing of PA indicators.
Measurement results and analysis
P
1dB
output power test
The power gain of the amplifier is commonly used to assess its linearity in terms of the power
point. Linearity is considered when the linear gain is less than 1dB, indicating that the relation-
ship between input and output no longer exhibits linear growth, as input power increases. This
results in the phenomenon known as gain compression, and specifically, the 1dB compression
point [70]. See Fig 21 for an illustration.
In the practical PA design, a higher P
1dB
value signifies better linearity. Thus, the output
power of the radar PA was assessed through a single controlled-variable method, within the
operational frequency range of 13.75GHz to 14.5GHz. The results were recorded using a
power meter and a spectrometer, as illustrated in Fig 22.
Fig 22(A) depicts the variation curve of the output power for the entire PA module, in rela-
tion to input power. It is evident from the figure that the output power in the linear operating
Fig 20. Experimental system test diagram.
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Fig 21. PA input-output relationship diagram.
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Fig 22. Output-power test-results graph. (a) Power-output test chart (b) Output-power flatness in frequency band (c) P
1dB
output power at 13.75GHz and
14GHz frequency points (d) P
1dB
output power at 14.25GHz and 14.5GHz frequency points.
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state, within the 13.75GHz to 14.5GHz band, increases with the input power. Additionally,
when the input is 0 dBm, the output power corresponds to P
1dB
. With a continuous increase in
input, the PA module enters a saturation state, reaching peak power values of 44.2dBm,
44.43dBm, 44.65dBm, and 44.38 dBm. Fig 22(B) illustrates the fact that the in-band output-
power flatness of the PA at different input powers is <0.5dBm. Fig 22(C) indicates that, at
0dBm input, the P
1dB
output power at the frequency points of 13.75GHz and 14GHz is
43.56dBm and 43.73dBm, respectively. Fig 22(D) shows us that at 0dBm input, the P
1dB
output
power at the 14.25GHz and 14.5GHz frequency points is 43.82dBm and 43.64dBm, respec-
tively. Experimental results confirm that, in the 13.75GHz to 14.5GHz frequency band, the PA
output power is >43dB, and its in-band flatness is <0.5dBm. This demonstrates good linear-
ity and compliance with the technical-index requirements for the designed star radar output
power.
To enhance the reliability assessment of the Ku-Band PA for satellite applications, we con-
ducted environmental cycling experiments, and specifically, limit experiments. These tests
involved exposing the amplifier to high temperatures (+60˚C) and low temperatures (-40˚C).
The chosen temperature range significantly exceeded the actual working temperature range of
the product in satellite environments. The findings from these experiments are graphically
depicted in Fig 23.
The reliability test process involves operating the amplifier in a saturated output state.
Fig 23(A) illustrates the fact that, at a frequency of 14GHz, the output power varies continu-
ously with the temperature, within the input-power range. Moreover, Fig 23(B) demonstrates
that, in the 13.75GHz to 14.5GHz band, the P
1dB
output power increases continuously with
decreasing temperature. Meanwhile, Fig 23(C) indicates that the output-power flatness in the
extreme temperature range is <0.3dBm, and Fig 23(D) shows that the output-power flatness
in the 13.75GHz to 14.5GHz band is <0.5dBm. The results of the environmental test at
extreme temperatures indicate that, within this range, the PA is influenced by the ambient
temperature, albeit to a minimal extent. The test results are more pronounced. The output
power of the PA across the entire frequency and temperature range complies with the design
specifications for satellite radar.
Third-order intermodulation (IMD3)
The nonlinear operating state of the PA induces intermodulation distortion, predominantly in
harmonics and cross-tuning [71]. Given that harmonic distortion and the output signal occur
at different frequency points, the second harmonic of the Ku-Band amplifier, at P
1dB
output, is
approximately -25dBc. This can be reduced to below -65dBc by incorporating a waveguide
harmonic-suppression filter at the amplifier output port, resulting in a suppression system
exceeding 40dBc at the harmonic position. Consequently, the associated impact can be disre-
garded. Incidentally, the most notable impact is on output-signal performance. The main dis-
tortion component in the intermodulation distortion is, in fact, third-order intermodulation
distortion. Since the driver-amplifier module has an ample power margin and operates line-
arly, the third-order intermodulation of the PA is primarily determined by the final amplifier
module. Consequently, the third-order intermodulation index curve of the final amplifier
module is derived through simulation. This process is illustrated in Fig 24.
According to the simulation curve of the final-stage amplifier chip, at a total power of a sin-
gle tone, decreasing from 46dBm to 7dBm (equivalent to the total power of a dual tone
decreasing from 46dBm to 4dBm, or the combined output of 42dBm), the single-chip output
power is approximately 28.5dBm. Simultaneously, the full frequency range of third-order
intermodulation in the final-stage amplifier is -23dBc, meeting the design requirements for
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third-order intermodulation in the final-stage amplifier. To further validate the third-order
intermodulation parameters of the entire system, the indicator was tested, as illustrated in
Fig 25.
Fig 25 reveals that the third-order cross-tuning of the PA, at frequency points 13.75GHz,
14GHz, 14.25GHz, and 14.5GHz, is -36.82dBc, -38.28dBc, -38.77dBc, and -36.52dBc, respec-
tively, surpassing the 23dBc threshold. This finding strongly confirms that the output signal is
minimally affected by the nonlinear effects of the amplifier, indicating excellent linearity and
adherence to the requirements of satellite radar applications. In summary, the intermodulation
component introduces spectrum-expansion issues in the amplifier, leading to spectrum waste.
To mitigate this problem, IMD3 should be minimized (typically below -40dBc), while trunca-
tion power should be judiciously increased. Subsequent strategies, such as the feed-forward
method, back-off method, and other auxiliary approaches, can be implemented to ensure and
enhance the overall linearity of the amplifier.
Power detection
The detector module performs real-time monitoring of the output power, concurrently mea-
suring both forward transmission power and reflected power. Additionally, it incorporates
Fig 23. Graph of environmental test results. (a) Input–temperature–output power (b) Frequency–temperature–output power (c) Output-power flatness at
the limit temperature (d) Output-power flatness in the full frequency band.
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various protection functions contingent on power levels. The power-detection performance of
the detector module is illustrated in Fig 26.
In Fig 26, within the 13.75GHz to 14.5GHz band, the forward coupler exhibits a coupling
degree of approximately -38dB, effectively amplifying the output power within the actual
range of 18 dBm to 54dBm. Specifically, at an amplifier output power of 46dBm, showcasing a
30dB large dynamic range, precise power detection is conducted in order to couple the RF sig-
nal. The signal is extracted at 9dBm, and subsequently, the voltage from the forward output
detector of the unit real-time monitoring amplifier is utilized to govern the gain attenuator.
This achieves a closed-loop adjustment function for output power. This process ensures sus-
tained accuracy in output power, maintaining the latter within ±0.5dB, in adherence to the
specified technical indicators.
Spurious and harmonic suppression
Spurious suppression. The spurious signal consists primarily of a frequency-conversion
component and a power-supply component. This will reduce the signal-to-noise ratio of the
output signal, and the range accuracy and distance resolution of the radar. Thus, in the present
paper, a systematic approach is implemented to suppress spurious responses [72]. First, the
spectrum combination indicates that the spurious level of the nearest part outside the band is
16.5GHz. This occurs when the local oscillation frequency is 11.5GHz, and the spurious fre-
quency point falls outside the range of 13.75GHz to 14.5GHz. Nonetheless, there remains a
2GHz frequency difference from the highest frequency of 14.5GHz in the passband. This signi-
fies that there is no intermodulation spurious level in the band, and the microstrip filter in the
Fig 24. Third-order cross-tuning simulation curve of the final-stage amplifier module.
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line suppresses more than 40dB. Combined with the third-order component power of about
25dB, a suppression system of more than 65dB is sufficient to facilitate spurious suppression.
Second, the frequency leakage of the local oscillation is also an important source of spurious
signaling; the local oscillation signal size of this program is 13dBm. Thus, leakage of the local
oscillation signal size to the RF channel is approximately -27dBm, corresponding to a level of
about -70dBm after 43dB suppression by the microstrip filter. Line-gain distribution can be seen
in the linear region of operation when its input power is -5dBm. At this time, the suppression sys-
tem evinces 65dB, to meet the requirements of spurious suppression. Additionally, the secondary
power supply has clear requirements for ripple indicators, while the amplifier module itself is
designed with a filtering circuit, in order to generate optimal transmission characteristics. In real-
life engineering applications, spurious suppression can be ensured above 65dB. In turn, this fulfils
the requirements of the index. The spurious suppression test is presented in Fig 27.
The results depicted in Fig 27 reveal spurious rejection coefficients of 69.38dBc, 71.77dBc,
73.3dBc, and 71.83dBc, at the frequency bands of 13.5GHz, 14GHz, 14.25GHz, and 14.5GHz,
respectively. This fulfills the stipulated requirement of harmonic rejection exceeding 65dB for
the star PA. These findings provide additional validation for the efficacy of the proposed rejec-
tion theory in enhancing spurious rejection.
Fig 25. Third-order intermodulation test results. (a) Third-order intermodulation at 13.75GHz, 14 GHz (b) Third-
order intermodulation at 14.25GHz, 14.5GHz.
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Harmonic suppression. The harmonic-rejection characteristics of the amplifier are
highly significant, and the potential harmonic distortion can be assessed through the second
harmonic-distortion input signal. This distortion can lead to increased compression phenom-
ena, and interference with other frequency bands. Consequently, the design process must care-
fully consider harmonic rejection [73,74]. This paper employs the load-traction suppression-
design approach to optimize the performance of the active device, complemented by the addi-
tion of a waveguide harmonic-suppression filter at the output of the amplifier. For the Ku-
Band amplifier, with a second harmonic P
1dB
output of approximately -25dBc, effective second
harmonic suppression is imperative, requiring levels below -60dBc for practical engineering
applications. The feasibility of the design was further scrutinized through relevant experimen-
tal tests, as depicted in Fig 28.
The test results presented in Fig 28 reveal significant harmonic rejection coefficients at
13.5GHz, 14GHz, 14.25GHz, and 14.5GHz bands, measuring -63.95dBc, 64.16dBc, -64.11dBc,
and -64.46dBc, respectively. Consequently, the harmonic rejection across the entire frequency
spectrum surpasses 60dBc, aligning with the specified requirements for Ku-Band PAs in star
applications. This information underscores the consistent harmonic-rejection performance of
the amplifier throughout the frequency band, exceeding the 60dBc threshold, and satisfying
the technical index standards for Ku-Band PAs.
Gain adjustment stability
In this investigation, gain adjustment is attained through the modification of the attenuation
level in the attenuator. Utilizing two CNC attenuators in a cascading design, we fulfill the crite-
ria for a 30dB dynamic range, ensuring control over gain and amplitude indices. Additionally,
Fig 26. Power-detector simulation diagram.
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this configuration exhibits improved in-band flatness characteristics. Simulation results, pre-
sented in Fig 29, illustrate the index curves corresponding to attenuation levels of 0.5dB, 1dB,
2dB, 4dB, 8 dB, and 16dB. These curves offer valuable insights into the attenuation process,
providing a comprehensive understanding of the performance of the system under various
attenuation settings.
Fig 29 indicates that the attenuation errors within the 0GHz to 40GHz range are minimal,
meeting all corresponding attenuation requirements. Concurrently, to ensure the stability of
this stellar PA in real-world applications, its attenuation performance has undergone rigorous
testing, with the results depicted in Fig 30, which showcases the measured attenuation values.
Fig 30 reveals that the attenuation levels at 13.5GHz, 14GHz, 14.25GHz, and 14.5GHz align
well with the simulation outcomes, displaying an attenuation error of 1%. To enhance atten-
uation performance, the implementation of a π-type attenuation network for impedance
matching is recommended, in subsequent debugging phases. This approach ensures the attain-
ment of optimal noise characteristics and attenuation responses.
For further assessment of gain stability within the amplifier frequency band, the power gain
provides insight (see Fig 31). The amplitude difference between the highest and lowest gains in
the band, denoted as ΔG (dB), serves as a crucial metric for evaluating the overall stability of
the gain of the PA throughout its operational spectrum.
It is evident from Fig 31 that the gains at 13.5GHz, 14GHz, 14.25GHz, and 14.5GHz bands
are 17.59dB, 17.38dB, 18.14dB, and 18.85dB, respectively, while the gain flatness in the band
from 13.5GHz to 14.5GHz is 1.47dB. As this is below 2dB, it meets the gain-flatness require-
ments of the system.
Fig 27. Spurious suppression test-result graph. (a) 13.5GHz spurious suppression (b) 14GHz spurious suppression
(c) 14.25GHz spurious suppression (d) 14.5GHz spurious suppression.
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Fig 28. Harmonic suppression test-result graph. (a) 13.5GHz harmonic suppression (b) 14GHz harmonic
suppression (c) 14.25GHz harmonic suppression (d) 14.5GHz harmonic suppression.
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Fig 29. Attenuation simulation graph.
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Discussion
Table 3 illustrated the results of our comparative analysis of various Ku-band PAs, set against
our current study. This PA has been meticulously designed, taking into account the specific
demands of satellite communication, ensuring exceptional performance and relative superior-
ity. Through adept design and innovative technical approaches, the amplifier has effectively
reduced noise, ensuring clear, high-quality signal transmission for satellite communication.
The robust 20W output power represents a significant breakthrough in signal-transmission
capability, establishing its leadership in the Ku-band PA domain. A holistic consideration of
critical technologies, including output-power flatness, spurious suppression, and harmonic
suppression, positions this PA as proficient in intricate communication environments, guaran-
teeing signal stability and purity. The adaptability of the amplifier is further enhanced by flexi-
ble gain and phase-adjustment features, catering to diverse communication scenarios and
requirements, thereby fortifying the applicability and robustness of the entire satellite commu-
nication system. Especially noteworthy is the transition of the amplifier from theoretical design
to successful deployment on satellites, with reliable operation. Validation through practical sat-
ellite applications lends substantial support to its advancement, infusing fresh energy into the
ongoing evolution of satellite-communication technology, and steering the trajectory of future
system development.
Conclusion
This paper introduces a novel Ku-Band 20W RF transmitting front-end PA, tailored to address
issues prevalent in satellite communication systems, such as poor stability, low linearity, high
Fig 30. Attenuation performance test-results graph. (a)Attenuation of 0.5dB (b)Attenuation of 1dB (c)Attenuation of 2dB (d)Attenuation of 4dB (e)Attenuation of 8dB
(f)Attenuation of 16dB.
https://doi.org/10.1371/journal.pone.0300616.g030
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Fig 31. Gain-test curve graph.
https://doi.org/10.1371/journal.pone.0300616.g031
Table 3. Performance comparison of Ku-band PAs.
References\
Specs [75] [76] [77] [78] [79] [80] [81]
This work
Freq (GHz) 12–
18
14.7–15 5–33 12–20 17.7–18.3 13.5–
18
2.3–21 13.75–14.5
NF (dB) 2.5 2.5 13.3 1.51 - - 4.56 1.2
Output P
1dB
power (dBm)
19 19.2 14 5 28.8 40 10.5 43
Output power
flatness(dBm)
1 0.6 3 dBm 2.8 0.5 0.5 - 0.5 dBm (Full
temperature section)
Stray
suppression
- - - - - - - -65 dBc
Harmonic
suppression
- - - - - - - -60 dBc
Gain
adjustment
- 1.5–17.3dB 24–27 dB, steps
of 10 dB
20.1–28 dB 0–21.4 dB, the gain
difference across 2:1
SWR phase
variations is only 0.8
dB
30–32
dB
an average gain of 13.5
dB with ripples of 0.2
dB, an excellent gain in
the flatness of 13.5 ±0.2
dB
0 dB-30 dB, steps of
0.5 dB, gain flatness
±2 dB, attenuation
error 1%
Phase shift
regulation
- 0˚-360˚, steps of
22.5˚, Phase shift
accuracy of 0.7–
0.8 dB
0˚-360˚, steps
of 4.7˚, Phase
shift accuracy
of 1 dB
the phase imbalance is
87.8˚ between ports 2,
3 and 2, 5 and 0.18˚
between ports 2, 4
- - -
0˚-360˚, steps of
5.625˚, Phase shift
accuracy of 0.5 dB
- Indicates that the study did not mention the indicator
https://doi.org/10.1371/journal.pone.0300616.t003
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A 20W Ku-Band RF front-end power amplifier design and deployment
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cost, low efficiency, and large size. The paper commences with an overview of the RF modules,
followed by a comprehensive theoretical analysis and simulation to establish an optimized
design methodology for the key parameters of the system. The low noise amplification design
of the PA is then theoretically calculated and optimized, accompanied by a detailed analysis,
index allocation, and simulation design for the system. Subsequently, the paper concludes with
the completion of the system design, prototype production of the PA, and experimental testing
to ascertain the feasibility of the proposed design scheme. Notably, the space simulation-envi-
ronment test results reveal that the Star Ku-Band PA surpasses 20W in output power, reaching
a peak power of 26W, with power fluctuation ±0.5dBm, third-order intermodulation
-23dBc, spurious rejection -65dBc, harmonic rejection -60dBc, power-detection range of
+18dBm ~ +54dBm, gain-adjustment range of 0dB - 30dB, phase-shift adjustment range of 0˚-
360˚, and gain flatness <1dB. These specifications align with the actual application require-
ments of the starboard technical indicators. This paper presents the development of a 20W RF
transmitter front-end PA in Ku-Band for satellites that, in contrast to existing PA module
specifications, offers advantages such as stability, high linearity, low cost, and small modular-
ity, while maintaining a stable power output. This positions the proposed system as a frontrun-
ner in the market. The successful deployment of the product in orbit has yielded positive
socio-economic benefits, playing a crucial role in advancing the localization process of China’s
satellite-based PA technology.
Supporting information
S1 Raw images.
(PDF)
Acknowledgments
This project relies on the innovation platforms of Shanghai University of Technology and
Anhui East China Institute of Photovoltaic Technology. I would like to thank Academician
Songlin Zhuang of the Chinese Academy of Engineering, Prof. Dawei Zhang, Researcher
Huaxia Wu, and Researcher Jinsong Liu for their help in this project.
Author Contributions
Conceptualization: Zhengxian Zhou, Tingzhen Yan.
Data curation: Huaxia Wu, Haima Yang.
Funding acquisition: Huaxia Wu.
Investigation: Dawei Zhang.
Methodology: Jiafa Chen, Jinsong Liu, Tianchen Tang.
Project administration: Jiafa Chen, Fei Wang, Dawei Zhang, Jinsong Liu.
Resources: Tianchen Tang.
Software: Jiafa Chen, Zhengxian Zhou, Haima Yang.
Supervision: Fei Wang, Tingzhen Yan.
Writing – original draft: Jiafa Chen.
Writing – review & editing: Jiafa Chen.
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