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Quantization of phase and/or amplitude has far-reaching effects on the radiation characteristics of the phased array (PA), including gain, minor lobe level, and point deviation. Traditionally, one common method to address such a nonlinear distortion is using random-phasing to interrupt the error periodicity. Here, we show that the distortion due to the quantization can be better remediated by spectrally shaping the error compared to the random-phasing (dithering) approaches. We adapted the method for phase-only and amplitude-phase synthesis of planar array designed based on analog beamforming (ABF). To do that, for the first time, 2-D real- and complex-coefficient minimum-phase digital finite impulse response (FIR) filters are designed based on the discrete Hilbert transform (DHT) method. In particular, the digital filter design for phase-only synthesis is comprehensively investigated, respecting the error spectra in the beamspace domain. It is shown that by pushing the error out of the so-called visible region, the decrease of antenna directivity due to the quantization can be compensated to some extent, which provides a quite advantage over the uniform distribution of error. For some cases, pushing the error out of the visible region might be impossible. For such cases, we proposed using the spaced-notches filter. It is also shown that the method is on maximum efficacy when both phase and amplitude of the excitation signal are controllable. Thus, complex-valued noise shaping (CV-NS) can be exploited for the phase-amplitude synthesis of the PA, showing quite promising performance. [ABSTRACT FROM AUTHOR]

In this study, a novel technique has been introduced for the first time, which is based on the transparent element to a specific polarization in order to realize bandpass frequency selective surfaces. It is shown that the proposed technique is more successful than preceding miniaturized structures presented in a variety of literature with respect to reducing the unit cell size. The element sizes of the structures are about 0.017λ0 to 0.053λ0. Furthermore, frequency response of the structures demonstrates perfect stability against the variations of the incident angle of the electromagnetic (EM) wave. [ABSTRACT FROM PUBLISHER]

In this letter, circularly polarized meshed patch antenna has been investigated. A new technique is proposed to provide circular polarization for meshed patch antenna. Moreover, two mesh configurations have been studied, and their opto-radio-electrical performances have been compared to each other. It is shown that there is a conflict between optical transparency and bandwidth of the antennas. Additionally, the Proximity coupling technique has been modified to feed the meshed patch providing more optical transparency for the whole assembly. In the current study, two fabricated circularly polarized meshed patch antennas are presented, one with copper ground plane, another with solar cell ground plane. Measurement results show 2.79% and 3.27% axial-ratio bandwidth (3 dB) at center frequency of 2.43 GHz as well as 4.9 and 4.4 dBiC gain for meshed patch antennas with copper and solar cell ground plane, respectively . [ABSTRACT FROM PUBLISHER]