In this article, we present a low-cost microstrip phased-array antenna, which is composed of electronically reconfigurable elements. The p-i-n diodes' integrated elements have various functions, such as tunable polarization characteristics and adjustable radiation phases. The high sidelobe level (SLL) due to the 2-bit phase shifter can be reduced by a randomly rotated (RR) array element. It is shown that the array can realize electronic beam-steering capabilities and keep -10 to -14 dB sidelobes without tapering. To verify the above theory, an eight-element linear array prototype working at 3 GHz was designed, fabricated, and tested. Numerical simulations and experimental results show that, by controlling the “ON” and “OFF” states of p-i-n diodes, the radiation beam can be controlled to steer in a circular polarization (CP) mode, wherein the scanning angle is up to ±45°. Furthermore, the principle of suppressing the vector scattering field by the opposite phasing cancellation method can achieve in-band radar cross section (RCS) reduction. Simulation results show that approximately 15 dB in-band RCS reduction can be realized for both bistatic and monostatic RCS reduction with an 8×8 array.

In this letter, we investigate a low radar cross-section (RCS) wideband circularly polarized microstrip array antenna co-designed with a high-performance artificial magnetic conductor and frequency selective surface (AMC-FSS) radome. Compared with the absorbent frequency selective radome-based antenna, the proposed co-designed antenna can achieve a relatively low gain loss in an extremely wide frequency range with wideband in-band and out-of-band RCS reduction, due to the introduction of a novel AMC-FSS radome which can achieve low insertion loss and wideband transmission by combining a double-layer miniaturized bandpass FSS and a single-layer chessboard AMC surface. We demonstrate the effectiveness of the proposed AMC-FSS radome and co-designed antenna through simulations and measurements. The results show that the gain deterioration of the co-designed antenna is only 0.42 dB at the central frequency of 4.8 GHz and less than 1 dB in the wide frequency band, ranging from 4.23 to 5.38 GHz with a relative bandwidth of 23.9%. At the same time, the monostatic RCS for a normal incidence is greatly reduced from 4 to 18 GHz.

In this article, a novel high-efficiency harmonic beamforming technique based on time-modulated arrays (TMAs) with multistate time modulators is proposed. The typical single-sideband TMAs suppress the image harmonic components in the radio frequency (RF) channel, which means low power conversion efficiency, large power consumption, and a major heat dissipation problem. To circumvent these constraints, we present a novel phase modulation (PM) waveform with a linear phase that can be easily constructed using multiple fixed delay lines and a pair of single-pole-multi-throw (SPMT) RF switches. This fundamental PM waveform enables the creation of uniform radiation patterns. Furthermore, two complementary methodologies are proposed for synthesizing more advanced radiation patterns that need nonuniform array weights. One method is to change the linear phase slope of PM waveforms that exhibit sideband radiation but have 100% feeding network efficiency. The other option is to investigate hybrid amplitude and PM (HAPM) waveforms, which suffer from inefficiencies in the feeding network but do not exhibit sideband radiation. Besides, the comprehensive efficiency evaluation formulas have been effectively derived. Simulations have been done to verify its effectiveness.

A novel slotted cavity antenna based on substrate integrated waveguide (SIW) technology using TE ₃₃₀ mode is presented for the first time. The SIW‐based cavity operating at TE ₃₃₀ mode is simply fed by a coaxial probe. Energy is coupled out of the cavity by a 3 × 3 slot array etched on the top surface of the cavity. An antenna prototype operating at WLAN 5.8 GHz band fabricated with standard printed circuit board (PCB) process on a single substrate is exemplified to validate the proposed concept. The overall volume of the antenna is 1.6 λ ₀ × 1.6 λ ₀ × 0.029 λ ₀ . Measured results show that the antennas achieve a bandwidth of 4.7% for 10 dB return loss and gain of up to 13.6 dBi. The proposed antenna features low profile, high gain, ease of fabrication and high efficiency, which makes it a good candidate for low‐cost mass‐production.

By combining convex programming (CP) and particle swarm optimization (PSO), a hybrid method for the synthesis of excitations and locations of nonuniformly spaced linear subarrays in order to minimize the subarray number is proposed and discussed in this paper. The synthesis problem herein is formulated as a CP problem by minimizing the l1-norm with respect to the excitation variables, and the PSO procedure is carried out as far as location variables are concerned. Through collaborations like this, we can finally get the optimal solution in a global sense. A set of representative numerical experiments shows the effectiveness of this method with quite a number of subarrays saved compared to the uniformly spaced layouts.

As a newly discovered evolutionary algorithm, the particle swarm optimization algorithm has been widely used in the synthesis of array antennas, while it is seldom used in the synthesis of nonuniform array antennas. Two different nonuniform array antennas are optimized by binary particle swarm optimization and real particle swarm optimization in this article, which depicts the application of particle swarm optimization in the synthesis of nonuniform array antennas. Lower peak side-lobe level with uniform excitation can be obtained using this method. Meanwhile, the method of minimizing variable-searching space that can improve the efficiency of algorithm is used in particle swarm optimization. Compared with the standard genetic algorithm and the modified real genetic algorithm, particle swarm optimization shows high performance in the synthesis of nonuniform array antennas. To demonstrate the universality of the algorithm, a nonuniform circular array and a sparse linear array with a directional element are synthesized as well.