A multi-layer X-Band microstrip array with beam tilt for FMCW-SAR application
01 Dec 2016-pp 1-4
TL;DR: In this article, a multi-layer tilted beam planar microstrip array for FMCW-SAR application is presented, where the common ground plane separating the two stacked substrate layers, shields the antenna half-space from spurious radiation emitted from the feed network.
Abstract: A multi-layer tilted beam planar microstrip array for FMCW-SAR application is presented The proposed 8×4 array antenna exhibits a beam tilt of 30 degrees in E-plane with a sidelobe level of 18dB and 20dB in H-plane without tilt The inherent radiation pattern degradation of the array due to feed radiation is minimized with the proposed multilayered concept The proposed design exhibits an improvement in sidelobe level of the order of 6dB in both E-and H-planes with better cross-polarization level In the multi-layered design, the common ground plane separating the two stacked substrate layers, shields the antenna half-space from spurious radiation emitted from the feed network The simulation results show that the radiation pattern in the operating frequency provides a 3dB beamwidths of 25° and 9° in E-plane and H-plane respectively Array exhibits a gain of 20dBi at the centre frequency and cross polarization level of better than 15dB
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01 Feb 2019
TL;DR: In this paper, a review of novel methods in realizing the low sidelobe level array antennas is presented, highlighting the concept of CSRR loading, inteferometry by end element loading, unequal spaced array, phase only synthesis for creating low sidelobes levels.
Abstract: This paper presents a review of novel methods in realizing the low sidelobe level array antennas. These methods highlight the concept of CSRR loading, inteferometry by end element loading, unequal spaced array, phase only synthesis for creating low sidelobe levels. In one of the approaches, Left hand media (LH) in the form of complementary split ring resonators (CSRRs) loaded array antennas is presented to achieve a sidelobe suppression of better than 10dB. In another approach, a synthesis technique of pattern interferometry in linear and planar arrays configurations is proposed, to exhibit control over the sidelobe suppression. Interferometry patterns are generated by loading one element each at the end of linear array. Alternatively genetic algorithms (GA) and its variations are used to create un-equal spacing between the antenna elements to create low sidelobe level array antennas. Multilayer planar array antennas are also proposed for sidelobe suppression and cross polarisation reduction.
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TL;DR: In this paper, a reconfigurable rectangular spiral antenna with a set of micro electro mechanical system (MEMS) switches, which are monolithically integrated and packaged onto the same substrate, is presented.
Abstract: A fully integrated solution providing scan-beam capability with a single antenna is presented in this paper for the first time. The proposed system includes a reconfigurable rectangular spiral antenna with a set of micro electro mechanical system (MEMS) switches, which are monolithically integrated and packaged onto the same substrate. The system is based on a single-arm rectangular spiral antenna, capable of changing its radiation pattern using radio frequency-MEMS (RF-MEMS) switches. The rectangular spiral and RF-MEMS switches are monolithically integrated on a conventional microwave substrate printed circuit board (/spl epsiv//sub r/=3.27 and tan/spl delta/=0.004) and quartz substrate (/spl epsiv//sub r/=3.78 and tan/spl delta/=0.0002). The spiral is made out of multiple lines, which are interconnected by RF-MEMS switches strategically located along the spiral. On activating these switches, the spiral overall arm length is changed and consequently its radiation beam direction is changed. The two proposed antennas radiate right hand circular polarization (RHCP) and left hand circular polarization (LHCP) for printed circuit board and quartz substrate respectively. The gain of the two antennas varies between 3/spl sim/6 dBi. They both satisfy the 3-dB axial ratio criterion at their operating frequency band, i.e., at 10 GHz and 6 GHz for the printed circuit board and the quartz substrate respectively. To the best of our knowledge, this is the first truly reconfigurable printed antenna design using MEMS devices as active elements integrated in the same low loss substrate. The excellent performance of the proposed system emphasizes the importance of being able to integrate MEMS switches into the same low loss substrate for antenna applications. This technology pioneers the design of arbitrarily shaped reconfigurable antennas including the design of reconfigurable antenna arrays.
400 citations
TL;DR: In this paper, a wideband coplanar waveguide was used to feed the balanced printed dipole antenna, where two silicon photo switches were placed on small gaps in both dipole arms equidistant from the center feed.
Abstract: A design for an optically reconfigurable printed dipole antenna is presented. A wideband coplanar waveguide (CPW) to coplanar stripline (CPS) transition is used to feed the balanced printed dipole. Two silicon photo switches are placed on small gaps in both dipole arms equidistant from the centre feed. Light from two infrared laser diodes channelled through fiber optic cables is applied to the switches. With the gaps in the dipole bridged, the antenna resonates at a lower frequency. Measured return loss results that compare well to the simulated values are also presented, showing a frequency shift of nearly 40%. The change in bore-sight gain along with radiation patterns are also presented. Activating each switch individually results in a near 50/spl deg/ shift in beam nulls.
323 citations
TL;DR: A fast beamforming algorithm based on simultaneous perturbation stochastic approximation with a maximum cross correlation coefficient criterion is proposed and the simulation and experimental results validate the algorithm.
Abstract: A low-power consumption, small-size smart antenna, named electronically steerable parasitic array radiator (ESPAR), has been designed. Beamforming is achieved by tuning the load reactances at parasitic elements surrounding the active central element. A fast beamforming algorithm based on simultaneous perturbation stochastic approximation with a maximum cross correlation coefficient criterion is proposed. The simulation and experimental results validate the algorithm. In an environment where the signal-to-interference-ratio is 0 dB, the algorithm converges within 50 iterations and achieves an output signal-to-interference-plus-noise-ratio of 10 dB. With the fast beamforming ability and its low-power consumption attribute, the ESPAR antenna makes the mass deployment of smart antenna technologies practical.
256 citations
TL;DR: In this article, a novel ground plane shape was proposed to improve the horizontal gain of ESPAR antennas. But the ground plane is not suitable for ground-based communication, as the peak directivity of a monopole antenna is at a higher angle from the horizon than that of a dipole antenna.
Abstract: A novel ground-plane shape to improve the horizontal gain for electrically steerable passive array radiator (ESPAR) antennas is investigated. The peak directivity of a monopole antenna with a finite ground plane, such as a circular or rectangular ground plane is at a higher angle from the horizon. Thus, the horizontal gain is lower than that of a dipole antenna. Using a circular ground plane of a half-wavelength radius with a skirt of a quarter wavelength wound around it, the angle of the peak directivity and the horizontal gain for the ground-based communication system were improved. For an ESPAR antenna - one of the monopole arrays - the horizontal gain was also improved. It was confirmed that it was possible to form the main-beam radiation and a beam null in the horizontal plane, each in an arbitrary direction, by changing the control voltage to the passive element. This was shown by an experiment with an ESPAR antenna with a finite reflector, a feed element, and seven passive elements.
193 citations
TL;DR: In this paper, the authors discussed the factors affecting the realizable sidelobe performance of microstrip arrays, including excitation amplitude and phase accuracies, mutual coupling, diffraction effects, positioning errors and errors due to imperfect element matching and feed network isolation.
Abstract: The factors affecting the realizable sidelobe performance of microstrip arrays are discussed and quantified. These include excitation amplitude and phase accuracies, mutual coupling, diffraction effects, positioning errors, and errors due to imperfect element matching and feed network isolation. It is shown that low-sidelobe microstrip arrays require a very tight tolerance on the resonant frequencies of the elements, and the elimination of spurious radiation from the feed network. Cross-polarization and surface wave effects are discussed. An experimental 16-element microstrip array prototype incorporated these considerations into the design, and achieved a -35 dB relative sidelobe level. >
114 citations