Fig 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Coax-fed, circular patch antenna. (a) Top view (substrate and ground plane disk have the same radius), and (b) side view (the coax feed is offset from the origin along the À^ y direction).
Source publication
When an electrically small antenna is conceived, designed, simulated, and tested, the main emphasis is usually placed immediately on its impedance bandwidth and radiation efficiency. All too often it is assumed that its directivity will only be that of a Hertzian dipole and, hence, its directivity becomes a minor consideration. This is particularly...
Contexts in source publication
Context 1
... the HFSS model of the coax-fed circular patch shown in Figure 1. The parameters already noted above remained the same. ...
Context 2
... semi-loop and the CLL element were again centered with respect to the coordinate origin. Figure 10 shows several of the simulated performance characteristics. It was resonant at f res = 299.798 ...
Context 3
... consider the rectangular EAD antenna. It is shown in Figure 11 along with its dimensions. The dielectric thickness was 0.7874 mm (31 mils). ...
Context 4
... gap between the end of the coax and the connection to the dipole was 1.5 mm. As shown in Figure 11c, the width of the driven dipole is DW = 2.0 mm, the same as the diameter of the center conductor of the coax. Its total length along the y-axis is DL = 12.301 mm. ...
Context 5
... simulated performance characteristics of the EAD antenna are shown in Figure 12 tivity pattern clearly indicates that the antenna acts as an electric dipole oriented along the y-axis. The RE value is larger than the EZ value; this is a recognized difference between the electric and magnetic antennas when their sizes become very electrically small [48,49]. ...
Context 6
... shown in Figure 8, these two NFRP antennas were configured into an array. More details of this two-element array are shown in Figure 13. Both the EAD and EZ elements fit within the indicated circle whose radius is 64.5 mm. ...
Context 7
... more, because it is primarily a magnetic field driven and because of its orthogonal orientation to the NFRP element, the EZ system is affected little by the presence of the EAD elements. The simulated performance characteristics of this array are shown in Figures 14 and 15. In Figure 14a, it is observed that the resonances of the two NFRP antennas overlap nicely. ...
Context 8
... simulated performance characteristics of this array are shown in Figures 14 and 15. In Figure 14a, it is observed that the resonances of the two NFRP antennas overlap nicely. The EZ antenna is resonant at f res = 299.79 ...
Context 9
... In Figure 14b, one finds that the radiation efficiency varies slightly with frequency and has its peak at 299.75 MHz, slightly below the EZ resonance frequency. Figures 14c and d give, respectively, the FTBR values and the accepted and total radiated powers. ...
Context 10
... Figure 14b, one finds that the radiation efficiency varies slightly with frequency and has its peak at 299.75 MHz, slightly below the EZ resonance frequency. Figures 14c and d give, respectively, the FTBR values and the accepted and total radiated powers. The maximum FTBR ratio, 2505 (34.0 dB), occurs at 299.07 MHz. ...
Context 11
... directivity patterns at 299.07 MHz where the maximum FTBR value occurs are shown in Figure 15. Figure 15a clearly shows the system generates a cardioid pattern. ...
Context 12
... directivity patterns at 299.07 MHz where the maximum FTBR value occurs are shown in Figure 15. Figure 15a clearly shows the system generates a cardioid pattern. As desired, the electric and magnetic dipoles combine to yield a Huygens source behavior. ...
Context 13
... of the strength of the EAD antenna's emissions in comparison with those of the EZ antenna, it was decided to simply short out the source element of the EZ antenna in the HFSS model. This configuration is shown in Figure 16. Note that the top view is identical to the one shown in Figure 14a. ...
Context 14
... configuration is shown in Figure 16. Note that the top view is identical to the one shown in Figure 14a. The elements were retuned slightly to achieve good impedance matching. ...
Context 15
... simulated performance characteristics of this array of two NFRP antennas with only the EAD element driven are shown in Figures 17 and 18. Figure 17a indicates that a good overlap of the resonances of both elements was achieved. ...
Context 16
... simulated performance characteristics of this array of two NFRP antennas with only the EAD element driven are shown in Figures 17 and 18. Figure 17a indicates that a good overlap of the resonances of both elements was achieved. From Figure 17b and c one finds that the frequencies at which the peak values of the radiation efficiency and the FTBR occur now coincide at 301.154 MHz. ...
Context 17
... simulated performance characteristics of this array of two NFRP antennas with only the EAD element driven are shown in Figures 17 and 18. Figure 17a indicates that a good overlap of the resonances of both elements was achieved. From Figure 17b and c one finds that the frequencies at which the peak values of the radiation efficiency and the FTBR occur now coincide at 301.154 MHz. The inset sub-plot in Figure 17c is a finer resolution of the FTBR values near its peak. ...
Context 18
... Figure 17b and c one finds that the frequencies at which the peak values of the radiation efficiency and the FTBR occur now coincide at 301.154 MHz. The inset sub-plot in Figure 17c is a finer resolution of the FTBR values near its peak. The peak FTBR value is 510.54 (27.0 dB) where RE = 95.31%. ...
Context 19
... peak FTBR value is 510.54 (27.0 dB) where RE = 95.31%. At that frequency, the accepted and total radiated powers are, respectively, 0.949 and 0.904 W. The 2D and 3D directivity patterns at 301.154 MHz are shown in Figures 18a and b, respectively. They clearly demonstrate that the desired cardioid pattern has been generated by this array. ...
Context 20
... previously discussed cases have provided further insights into the electrically small, low-profile broadside radiating, Huygens source antennas [22][23][24]. The configu- ration of interest is shown in Figure 19. It is a smaller, thinner design than reported in [22] and emphasizes just how electrically small the Huygens antenna can be and still produce the desired cardioid pattern. ...
Similar publications
A compact, high gain, single layer substrate-superstrate configuration based Fabry–Perot cavity (FPC) microstrip patch antenna (MPA) is designed. It consists of a single-frequency MPA on a substrate, along with a frequency-selective surface (FSS) which acts as a metasurface-superstrate. The FSS contains a periodic arrangement of unit cells in a squ...
The use of microstrip patch configuration in the 5th generation (5G) wireless network is expected to fulfill the demands of smartphone users by significantly increasing the capacity of the communication technology. The main aim of this paper is to disclose the development of a mathematical model on the effects of conductive material and substrate t...
In this article, a novel design of multiband microstrip patch antenna has been presented for multiband applications. The Shirt shape antenna is designed on FR-4 substrate and is fed through 50 ohm microstrip feed line. Two l-shape slots are introduced in antenna for size reduction and to provide multiband characteristics while DGS (defected ground...
A wideband antenna with dual band characteristic at 5.33/14.3GHz with resonating frequencies for wireless applications is presented. The strategy of the design is to introduce multiband in antenna band. Bandwidth of the antenna increases by embedding annular ring on the radiating patch and four bands are achieved by introducing coupling gap between...
In this article, a completely unique design of multiband microstrip patch antenna has been presented for multiband applications. The C-shape antenna is meant on FR-4 substrate and is fed through 50 ohm microstrip feed line. Three l-shape slots are introduced in antenna for size reduction and to supply multiband characteristics to realize bandwidth...
Citations
... Recall that the basic design is a form of the 2-D magnetic EZ antenna [46]. As demonstrated in [53], the majority of the currents on the ground plane are confined near the magnetic EZ radiators. As a consequence, decreasing the radius of the ground plane would have little impact on the impedance matching, but it would cause the peak realized gain to decrease some as the front-to-back ratio (FTBR) value does [53]. ...
... As demonstrated in [53], the majority of the currents on the ground plane are confined near the magnetic EZ radiators. As a consequence, decreasing the radius of the ground plane would have little impact on the impedance matching, but it would cause the peak realized gain to decrease some as the front-to-back ratio (FTBR) value does [53]. The size of the ground plane of the XESA was selected simply for convenience in handling it during the measurement campaign. ...
... The currents on the ground plane associated with the magnetic EZ antennas responsible for impedance matching are basically within the radian-sphere associated with its NFRP element, the main radiator [53]. Also recall that the gain of an antenna is the product of its efficiency times its directivity [63]. ...
Extremely electrically small antennas (XESAs) exhibit low gain performance, which seriously limits their applications in space-constrained wireless platforms. We report an active transmitting XESA whose gain-bandwidth product (GBWP) exceeds the passive Bode-Fano upper bound. It is realized by incorporating a highly efficient, electrically small, near-field resonant parasitic (NFRP) antenna into the feedback loop of an operational amplifier (OpAmp). Rather than a cascaded configuration, the innovative structural embedding of the NFRP antenna directly with the OpAmp circuit significantly increases its effective gain without consuming any additional real estate. The operating mechanisms of the integrated system are explained with an equivalent circuit model. An optimized prototype was fabricated, assembled, and tested. The electrical size of its radiating element is extremely small with
ka
= 0.15 at 414 MHz, i.e.,
$a~\approx \lambda $
/42. The measured results of this active XESA, in good agreement with their simulated values, demonstrate that its effective gain can be dynamically tuned within a 6.01 dB range. The measured maximum effective gain and, hence, the effective isotropic radiated power (EIRP) witnesses a 9.152 dB (8.23 times) improvement in comparison to its passive counterpart and its measured GBWP surpasses the corresponding passive Bode-Fano upper bound by approximately 15.2 times.
... -les sources de Huygens, qui utilisent le couplage entre un dipôle magnétique et un dipôle électrique de petites tailles pour obtenir l'équivalent d'une source théorique de Hygens [?, [101][102][103][104][105]. ...
Durant cette thèse nous nous sommes intéressés à la physique des ondes globale. En repartant de l’équation de d’Alembert, il émerge trois leviers principaux qui permettent le contrôle des ondes : contrôle sur les sources, contrôle sur les conditions aux limites, et contrôle sur le milieu de propagation lui-même. Dans un premier lieu, nous avons utilisé les propriétés d’une métasurface binaire électroniquement reconfigurable en cavité micro-ondes. Cet objet permet de contrôler le champ au sein de la cavité. Celle-ci a ensuite été ouverte, et nous avons montré que le contrôle s’étendait à l’émission en champ lointain. Ce système réalise donc une antenne compacte directive et reconfigurable. Dans un second temps, nous avons considéré l’approche métamatériaux pour réaliser une antenne dite superdirective. En effet, les antennes sont soumises à des limitations de directivité liées à leur taille, dont la prédiction date des années 40. En utilisant un milieu de fils, nous avons montré que ce métamatériau qui permet le contrôle du champ proche à une échelle sub-longueur d’onde, peut influencer le rayonnement d’une source unique au point de réaliser une antenne superdirective avec seulement quatre diffuseurs résonants passifs. Enfin, nous avons réalisé en acoustique une preuve de concept d’une nouvelle technique d’imagerie non-linéaire. Depuis l’illumination structurée, c’est l’imagerie d’agents de contraste, souvent fluorescent, qui permet de battre la limite de diffraction. Ici, nous proposons une idée basée sur l’effet Doppler. Nous montrons dans un premier temps qu’imager avec des sources et des récepteurs en rotation permet d’égaler au moins l’illumination structurée. Dans un second temps, nous montrons que cette rotation génère une information spectrale supplémentaire qui permet d’atteindre la super-résolution.
... Mounting the ESA on a steel barge partially submerged in sea water increases the directivity of the antenna with a narrower HPBW as a result of having a more substantial ground plane with a larger amount of power being directed upwards. This is in part due to the longer path that any reverse current must travel, in addition to the radiated fields no longer having sufficient magnitude to excite the large plane (Ziolkowski, 2017). The barge itself provides much of the additional gain being 32 m wide while the sea water's contribution to the overall gain is small. ...
... In addition to shifting the radiation pattern, ground plane size influences the maximum gain available with larger ground planes providing higher gain, as expected, Fig. 13, with a 20 m ground plane being an acceptable compromise between size and available gain. There is a point of diminishing returns occurring at approximately 30 m, where the large ground plane is fully excited by the radiated fields (Ziolkowski, 2017). ...
An Electrically Small Antenna (ESA) is evaluated for use as the principle radiating element in a Mobile Ionospheric Heating (MIH) array. Consisting of a Small Loop Antenna (SLA) inductively coupled to a Capacitively Loaded Loop (CLL) the ESA provides high efficiency with the capability of being tuned within the range of ionospheric heating. At a factor 60 smaller in area than a HAARP element, this antenna provides a compact, efficient radiating element for MIH. A prototype antenna at 10 MHz was built to study large scale feasibility and possible use with Photo‐Conductive Semiconductor Switch (PCSS) based drivers. Based on the experimental study, the design has been extrapolated to a small 6x4 array of antennas. At a total power input of 16.1 MW this array is predicted to provide 3.6 GW ERP typically required for ionospheric heating. Array cross talk is addressed, including effects upon individual antenna port parameters. Tuning within the range of ionospheric heating, 3 – 10 MHz, is made possible without the use of lossy dielectrics through a large capacitive area suited to tune the antenna. Considerations for high power operation across the band are provided including a method of driving the antenna with a simple switcher requiring no RF cabling. Source matching may be improved via adjustment of the coupling between SLA and CLL improving |S11| from ‐1 to ‐21 dB at 3 MHz. •Electrically Small Antenna at 3 ‐ 10 MHz designed for use in Transportable Ionospheric Heating array •Tuning methods for achieving tuning bandwidth, optimal port matching tuning presented and considerations for high power operation •Simple array design for ionospheric heating presented with array considerations including coupling or cross talk effects
Autonomous teams of unmanned ground and air vehicles rely on networking and distributed processing to collaborate as they jointly localize, explore, map, and learn in sometimes difficult and adverse conditions. Co-designed intelligent wireless networks are needed for these autonomous mobile agents for applications including disaster response, logistics and transportation, supplementing cellular networks, and agricultural and environmental monitoring. In this paper we describe recent progress on wireless networking and distributed processing for autonomous systems using a low frequency portion of the electromagnetic spectrum, here defined as roughly 25 to 100 MHz with corresponding wavelengths of 3 to 12 meters. This research is motivated by the desire to support autonomous systems operating in dense and cluttered environments by harnessing low frequency propagation, where meters long wavelengths yield significantly reduced scattering and enhanced penetration of obstacles and structures. This differs considerably from higher frequency propagation, requiring different low frequency propagation models than those widely employed for other bands. Progress in use of low frequency for autonomous systems has resulted from combined advances in low frequency propagation modeling, networking, antennas and electromagnetics, geolocation, multi-antenna array distributed beamforming, and mobile collaborative processing. This article describes the breadth and the depth of interaction between areas, leading to new tools and methods, especially in physically complex indoor/outdoor, dense urban, and other challenging scenarios. We bring together key results, models, measurements, and experiments that describe the state of the art for new uses of low frequency spectrum for multi-agent autonomy.
Anytime‐wireless‐everywhere (AWE) aspirations for Internet‐of‐things (IoT) applications to be enabled through current 5G and evolving 6G and beyond ecosystems necessitate the development of innovative electrically small antennas (ESAs). While a variety of ESA systems are reviewed, those realized from the near‐field resonant parasitic (NFRP) antenna paradigm are emphasized. Efficiency, bandwidth, and directivity issues are highlighted. Multifunctional, reconfigurable, passive and active systems that have been achieved are discussed and illustrated; their performance characteristics and advantages described. This overview finalizes by going back to the future and considers enterprising research areas of current and forward‐looking interest.
Non-Foster technology facilitates the ability to surpass the Chu bandwidth limit associated with electrically small antennas (ESAs). Nonetheless, in addition to challenging stability issues, the enhanced performance can come at the cost of increased noise and resistance losses generated by the active circuit. Consequently, low total efficiency and degraded signal-to-noise ratio (SNR) values can arise. Stability and SNR have dominated most reports to date; little has been discussed about the underlying innovative physics of non-Foster augmented radiators. In this communication, we propose a broad bandwidth non-Foster ESA, emphasizing those aspects. By embedding a non-Foster element into the near-field resonant parasitic (NFRP) element of a metamaterial-inspired antenna, its electrically small size is maintained. On the other hand, a 5-times enhancement of its -10-dB fractional bandwidth (15-times its -3-dB bandwidth) is measured, significantly surpassing its passive Chu limit. Under good matching, the measurements demonstrate that this non-Foster ESA achieves a 1.05 dBi peak gain, and realizes average 5.0 dB SNR and 17 dB gain improvements over its passive counterpart.
