Figure - available from: Journal of Infrared, Millimeter and Terahertz Waves
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Three coupling ways: (a) symmetrical H-plane magnetic coupling, (b) E-plane electric coupling, and (c) H-plane offset coupling
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In this paper, a high-performance waveguide bandpass filter (BPF) operating at W-band is proposed. This fifth-order BPF with a wide fractional bandwidth (FBW) of 20% is realized by adopting strong H-plane offset magnetic coupling, while maintaining a simple and robust structure for the computer numerical control (CNC) milling technology. An extra t...
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A novel adjustable dual-band bandpass filter using a quantic-mode resonator consisting of stepped impedance resonators (SIRs) and coplanar waveguide resonators (CPWRs) is proposed in this paper. The SIRs provide the lower passband with two transmission poles (TPs), while the upper passband is introduced by CPWRs and two TPs are obtained. Furthermor...
Citations
... Compared with the substrate-based transmission lines such as substrate-integrated waveguide (SIW) [14,15], microstrip line [16] and coplanar waveguide (CPW) [17], the air-filled rectangular waveguide can exhibit advantages of low insertion loss, high Q-factor, high power handling, and simple assembling. Thus, rectangular waveguides are preferred as the transmission lines to construct BPFs [18][19][20][21][22][23][24][25][26][27], active circuits [7][8][9] as well as systems [2] from the W-band to THz band. However, the physical dimensions suffer from high precision requirements due to short wavelength and small size of the W-band BPFs. ...
... Thus, the most popular method for producing waveguide components is still the computer numerical control (CNC) milling technique using a split-block way. This technology can strengthen physical robustness while simplifying the assembling and interconnection, such as the W-band filters in [24][25][26][27][28][29][30][31]. In addition, the cross-coupling, extracted poles and high-order modes have been introduced to achieve the advanced quasi-elliptical filtering responses [26][27][28][29][30][31]. ...
... For most waveguide filter designs [18][19][20][21][22][23][24][25][26][27][28][29][30][31], the fundamental TE 101 mode is generally considered to construct the filter passband. Each resonator cavity can support multiple harmonic resonances due to high-order modes; however, it will lead to introducing undesired passbands [21,36]. ...
In this paper, a W-band waveguide bandpass filter with a standard fourth-order Chebyshev response is proposed based on the computer numerical control (CNC)-milling technology. The harmonics-staggered technique and orthogonal coupling method are incorporated into this waveguide filter design without increasing the complexity of the filter structure in order to suppress the intrinsic spurious responses near the passband. Furthermore, the proposed filter design maintains a simple construction, which can be conveniently fabricated using CNC milling. The fabricated waveguide filter exhibits an average insertion loss of 0.9 dB and a return loss of above 20 dB in a 3 dB fractional bandwidth (FBW) of 5.5% centered at 85 GHz. The excellent spurious suppression property can reach better than −25 dB up to 165 GHz. The wide stopband performance of the proposed W-band filter is very competitive compared with the reported waveguide filters.
... Rectangular waveguides (RWGs), with the merits of low-losses and high powerhandling capability, are preferred for filtering modules at such high-frequency band. RWG BPFs operating at W -band can be used in the high-speed wireless space communication systems such as radio astronomy [3], imaging radar [4], and remote sensing [5], which require low loss and high power capacity. Conventional W -band RWG BPFs are mainly based on resonators with multiple transmission zeros [3], [4], [5], [6], [7], [8], [9], [10]. ...
... RWG BPFs operating at W -band can be used in the high-speed wireless space communication systems such as radio astronomy [3], imaging radar [4], and remote sensing [5], which require low loss and high power capacity. Conventional W -band RWG BPFs are mainly based on resonators with multiple transmission zeros [3], [4], [5], [6], [7], [8], [9], [10]. However, most Manuscript of these BPFs cannot control the lower and upper cut-off frequencies flexibly and independently. ...
... These results confirm that the proposed BPF exhibits a good bandpass propagation feature in the W -band. The performance comparisons of different BPFs based on RWG [3], [4], [5], [6], [7], [8], [9], [10] and SSPP [19], [20], [21] are listed in Table I, where f 0 is the center frequency. Compared with the BPFs based on RWG [3], [4], [5], [6], [7], [8], [9], [10], our filter can adjust the lower and upper cut-off frequencies as well as bandwidth flexibly and independently. ...
A hybrid circuit with spoof surface plasmon polaritons (SSPPs) and double-grating rectangular waveguide (DG-RWG) is proposed to design a bandpass filter (BPF) operating at
W
-band. The proposed SSPPs consisting of corrugated metallic blocks are embedded into the RWG, which forms a hybrid SSPP-RWG. Both the dispersion curves of the SSPP-RWG and DG-RWG are analyzed. The lower cut-off frequency of DG-RWG and the upper cut-off frequency of SSPP-RWG can be controlled independently by changing their geometric parameters, thus the hybrid circuit composed of DG-RWG and SSPP-RWG is attractive to design a BPF with tunable bandwidth. For demonstration, a
W
-band RWG BPF is designed and fabricated with measured bandwidth from 80.1 to 93.8 GHz, which agrees well with that in the dispersion curves. The BPF has a low insertion loss of about 0.57 dB at the center frequency.
... Rectangular waveguides (RWGs), with the merits of low-losses and high powerhandling capability, are preferred for filtering modules at such high-frequency band. RWG BPFs operating at W -band can be used in the high-speed wireless space communication systems such as radio astronomy [3], imaging radar [4], and remote sensing [5], which require low loss and high power capacity. Conventional W -band RWG BPFs are mainly based on resonators with multiple transmission zeros [3], [4], [5], [6], [7], [8], [9], [10]. ...
... RWG BPFs operating at W -band can be used in the high-speed wireless space communication systems such as radio astronomy [3], imaging radar [4], and remote sensing [5], which require low loss and high power capacity. Conventional W -band RWG BPFs are mainly based on resonators with multiple transmission zeros [3], [4], [5], [6], [7], [8], [9], [10]. However, most Manuscript of these BPFs cannot control the lower and upper cut-off frequencies flexibly and independently. ...
... These results confirm that the proposed BPF exhibits a good bandpass propagation feature in the W -band. The performance comparisons of different BPFs based on RWG [3], [4], [5], [6], [7], [8], [9], [10] and SSPP [19], [20], [21] are listed in Table I, where f 0 is the center frequency. Compared with the BPFs based on RWG [3], [4], [5], [6], [7], [8], [9], [10], our filter can adjust the lower and upper cut-off frequencies as well as bandwidth flexibly and independently. ...
In this article, spoof surface plasmon polariton (SSPP) is developed in a groove gap waveguide (GGW) to realize an adjustable bandpass filter for
Ka
-band applications. The proposed SSPP structure consists of a single row of corrugated metallic blocks, which is embedded into the groove of GGW. The lower cut-off frequency of the passband can be adjusted by changing the groove width or pin height, and the upper cut-off frequency of the passband is determined by the period or height of the SSPP unit cell through dispersion and S-parameter analysis. For demonstration, a GGW-SSPP bandpass filter is fabricated and measured based on the proposed method. The measured bandwidth is from 29.8 to 35.8 GHz, which is in agreement with that of the simulated one. The proposed GGW-SSPP filter can achieve adjustable bandpass characteristics with a low insertion loss of 0.22 dB owing to the application of GGW.
... As detailed in Table 3, most of the devices previously proposed in W-band aimed for wider passbands, which facilitated the fabrication process. This is the case of the structures presented in [12,17,19,20], where the filters have been implemented in rectangular waveguide. Good results can be achieved with devices fabricated by CNC milling and also by SLA 3D-printing, when wide passbands are considered. ...
In this paper, a W-band 3D-printed bandpass filter is proposed. The use of higher-order TE 10 n modes in groove gap waveguide (GGW) technology is evaluated in order to alleviate the manufacturing requirements. In addition to the use of higher-order modes, the coupling between them is analyzed in detail to improve the overall fabrication robustness of the component. This allows the implementation of narrow-band filters operating at millimeter-wave frequency bands (or above), which usually demand complex manufacturing techniques to provide the high accuracy required for this kind of devices. In order to show the applicability of the proposed method, a narrow-band 5th-order Chebyshev bandpass filter centered at 94 GHz, which can be easily fabricated by state-of-the-art stereolithographic (SLA) 3D-printing techniques followed by silver coating, is shown. Excellent measured performance has been obtained.
... The coupled resonator is one of the mainstream technologies for the waveguide filter [31,32]. When the metal iris is loaded in the direction of the broadside of the waveguide, it is equivalent to compressing the electric field and showing the property of capacitance. ...
In this paper, a novel full waveguide matching method (FWMM) is proposed to improve design efficiency and verify the feasibility of full waveguide matching for terahertz frequency doubler. In the proposed method, the frequency doubler is divided into three parts: packaging diode, input matching waveguide, and output matching waveguide, each of which realizes different functions. The most important diode embedding impedance matching part is transferred from the microstrip to the input and output matching waveguide. The impedance matching of the waveguide is realized by the structure called quasi-coupled resonator. These quasi-coupled resonators are implemented by inserting irises at the broadside of the waveguide and function as a capacitive load for the circuit. Using this method, a compact and efficient frequency doubler was designed and characterized. Measured results show that the peak efficiency of the doubler is 25.8% at 215 GHz with 50 mW input power. The good output performance of the 220 GHz doubler verifies the effectiveness of the proposed full waveguide matching method.
... Comparing with the substrate-based transmission lines, which have significant losses in the MMW, sub-MMW, and THz bands, such as substrate-integrated waveguides [6,7], coplane waveguides and dielectric resonators [8], filters [9][10][11][12][13][14][15][16] based on the traditional rectangular waveguide can avoid the electromagnetic radiation loss nor dielectric loss, while can exhibit advantages of low loss, simple assembling and easy interconnection. So far, a variety of design methods and machining technologies have been proposed for W-band waveguide filters to obtain high performance, such as low loss, sharp response and high out-of-band suppression. ...
... So far, a variety of design methods and machining technologies have been proposed for W-band waveguide filters to obtain high performance, such as low loss, sharp response and high out-of-band suppression. Table 1 has shown the performance comparison of typical W-band filters [6][7][8][9][10][11][12][13][14][15][16]. It is obvious that such filters can be attributed to two categories as, ones machined by the computer numerical control (CNC) [9][10][11][12][13] and the others processed through novel micro-technologies [14][15][16]. ...
... Table 1 has shown the performance comparison of typical W-band filters [6][7][8][9][10][11][12][13][14][15][16]. It is obvious that such filters can be attributed to two categories as, ones machined by the computer numerical control (CNC) [9][10][11][12][13] and the others processed through novel micro-technologies [14][15][16]. Among them, waveguide filters fabricated by CNC-milling have obtained features of physical robustness, integrated flanges and solid-state interconnection. ...
The development of multi‐pixel receivers on the millimetre‐wave and terahertz bands demands on the integration of key waveguide devices. In this paper, two waveguide bandpass filters operating at the W‐band are developed based on the layered integration architecture. First, the traditional fourth‐order waveguide filter is perpendicularly folded to realise dual‐layered arrangement, meanwhile a cross‐coupling between layers is introduced to obtain the standard quasi‐elliptical response. Then, two layered approaches including 5‐layer and 3‐layer are proposed to fabricate filter prototypes integrating with 90° curved waveguides based on the computer numerical control (CNC) technology. Finally, the measurement exhibits that both filters have achieved the 3 dB fractional bandwidth of 14.8% from 85 to 98.5 GHz, low insertion loss of 0.6 dB (5‐layer) and 0.4 dB (3‐layer), the return loss with better than 20 dB, as well as two obvious transmission zeros in the out‐of‐band. Besides, the layering error analysis and performance comparison of both filters are discussed, which verify the feasibility of the layered integration for CNC‐machined W‐band waveguide filters.
... However, with the development of B5G and 6G communication technologies and the formulation of related communication protocols, the working frequency bands of high-frequency millimeter waves need to be divided in more detail. As the first blank millimeter-wave frequency band after the division of the B5G communication frequency band, the W-band has attracted the attention of millimeter-wave researchers from various countries because of its available frequency bandwidth and relatively small influence of atmospheric attenuation [4][5][6]. ...
A W-band quadruple-passband millimeter-wave cavity filter based on the theory of non-resonant nodes is reported in this paper. First, a single-band millimeter-wave band-pass cavity filter with a working frequency in the W-band is designed. Its structure is composed of a rectangular resonant cavity and a rectangular waveguide, and the working frequency band is 85.19 ~ 104.52 GHz. Then, the non-resonant node transmission theory is used to introduce transmission zeros in its band-pass frequency band; a millimeter-wave cavity filter with four band-pass frequency bands is designed. Its operating frequencies are 85.49 ~ 86.70 GHz, 87.01 ~ 93.40 GHz, 94.00 ~ 101.70 GHz, and 102.06 ~ 104.49 GHz, respectively. The cavity filter designed in this paper is made using computer numerical control (CNC) technology, and the W-band electromagnetic test platform is built by using a vector network analyzer and a spread spectrum module to complete its test. The test results are basically the same as the simulation results.
Graphical abstract
The theoretical basis, structural optimization, and test analysis of the four-band cavity filter based on the non-resonant node theory.
... The design forms of W-band filter mainly include microstrip, 1 waveguide, [2][3][4][5][6][7][8] and substrate integrated waveguide (SIW). 9 In W band, the radiation loss of the microstrip line increases significantly, and the filter based on this structure exhibits a relatively high insertion loss, therefore it is no longer suitable for the filter design. ...
This paper presents a miniaturized W-band bandpass filter based on rectangular micro-coaxial structure. The filter with third-order Chebyshev response is analyzed and designed. It uses half-wavelength resonators and realizes the coupling between resonant units by adding grounded cylinders. The center frequency is 97.5 GHz with 3-dB fractional bandwidth (FBW) of 7.5%. Moreover, the prototype is fabricated by the surface micromachining technology, which greatly reduces its volume. The measured results are close to the simulations in operating band and the minimum insertion loss is 1.9 dB.
... In W-band, waveguide filters are widely used because of the superiorities of high cavity quality (Q) value, low loss and high power capacity compared to microstrip filter. [1][2][3] The common structure of waveguide filters is that multiple resonant cavities are arranged in a straight line, 4,5 and the coupling between resonant cavities is adjusted by controlling the size of inductive or capacitive irises. Cross-coupling can be achieved by changing the arrangement of resonant cavities, which produces transmission zeros and improves the selectivity of the filter. ...
In this paper, a novel E‐plane waveguide bandpass filter with multiple transmission zeros is proposed in W‐band. The center frequency and bandwidth of this filter can be flexibly designed. Stripe line resonators and L‐shaped resonators are used in the filter. The filter contains four resonators, two of which are used to generate transmission zeros in the upper stopband, and the other two are used to generate transmission zeros in the lower stopband. These transmission zeros can enhance the out‐of‐band suppression and selectivity of the filter. And the position of the transmission zeroes can be flexibly changed as required. One sample is fabricated and measured to verify the proposed filter. The minimum insertion loss in passband is 0.6 dB. Good agreements between the simulated and measured results are achieved.
... This trade-off can be exploited for compact and lightweight components when employed appropriately but inversely comes at the cost of requiring high-precision manufacturing capabilities. In regards to W-band filters, only a few computer numerical control (CNC) milled designs have been demonstrated in the literature with elliptical/quasi-elliptical response [2][3][4][5][6][7][8][9][10][11], many of which rely on the use of source-load coupling techniques for the generation of additional transmission zeros but can go on to require bulky corner transitions. In this letter, we demonstrate an inline full-wave sixth-order quasi-elliptical filter with approximately 2% fractional bandwidth centred around 97.5 GHz by utilising symmetric E-plane and H-plane doubly loaded irises. ...
Abstract In this correspondence, high‐precision computer numerical control milling is utilised to demonstrate a doubly loaded iris, cross‐coupled waveguide bandpass filter for inline operation within the W‐band. This sixth‐order filter is designed in a stacked H‐plane configuration and utilises both E‐plane and H‐plane doubly loaded irises to maintain the flow of a TE102‐mode electromagnetic field. In this configuration, a high rejection level is maintained outside of the passband while a good unloaded quality factor is obtained through the support of larger resonator dimensions. The filter is designed for approximately 2% fractional bandwidth centred at 97.5 GHz and has been fabricated as three brass components. Measurements of the filter agree very well with the simulated results and demonstrate a spurious‐free design over the full W‐band.
