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In this paper, a wideband polarization reconfigurable omnidirectional antenna (PROA) based on a single-substrate active metasurface is proposed. By controlling the states of the PIN diodes, the antenna can selectively radiate an omnidirectional linearly polarized wave and an omnidirectional circularly polarized wave. The reflection coefficient, axial ratio (AR), radiation pattern, and gain of the proposed antenna have been analyzed from the perspective of simulation and measurement. The measured results show that the PROA has a wide overlapped bandwidth from 2.87 to 3.67 GHz (relative bandwidth 24.46%). To the authors' best knowledge, this is the first reported wideband PROA based on a single-substrate reconfigurable polarization converter. This study not only offers a novel approach to design PROAs, but also greatly reduces the design complexity of the feed source compared with the traditional design method of PROAs. [ABSTRACT FROM AUTHOR]

The operating bandwidth of miniaturized magnetoelectric (ME) antenna is generally narrow due to the acoustic wave driven magneto-electromechanical resonance effect, parallel connection of multiple ME antennas with different resonant frequencies is an effective way to broaden the operating bandwidth of the antenna. This paper presents an ME antenna array consisting of three units, which are constructed of a sandwich stack of Metglas/Pb(Mg1/3Nb2/3)O3–PbTiO3/Metglas. The −3 dB operating bandwidth of 152.4–172.8 kHz is achieved, and the relative bandwidth is 12.5%. Experimental results indicated that the bias magnetic field and coupling effect between the ME antenna units significantly influence the performance of ME antenna array. A modified Butterworth–Van Dyke (MBVD) equivalent circuit model is used and improved to analyze the influence of sound waves, electric fields, magnetic fields, parasitic capacitance, and bias magnetic field on the ME antenna array. The simulation results of the MBVD equivalent circuit model are agreed well with the experimental results. The improved MBVD model is beneficial for the design of acoustic wave driven antenna array. [ABSTRACT FROM AUTHOR]

The utilization of polarization conversion metasurfaces (PCMs) has enormously facilitated the capabilities of numerous wireless systems and optical devices. However, the cross‐polarization conversion performed by the PCM inevitably results in a parasitic filtering effect that severely hinders its capacity to receive multiple polarization waves. In this paper, a high‐efficiency transmissive PCM based on the non‐reciprocal metasurface integrated with the NPN transistors is proposed, which can convert both input x‐ and y‐polarized waves into the y‐polarized transmitted wave, meanwhile, the parasitic filtering effect of the polarization converter is effectively eliminated. The total transmission efficiency of orthogonal polarizations is higher than 50% within 3.26–3.39 GHz, excluding the gain from the transistor‐based circuits, and the peak efficiency reaches 85.4% at 3.35 GHz. In addition, the proposed PCM opens up the possibilities for expanding the range of received polarization states. For the conceptual demonstration, the conversion from arbitrary linear polarizations to y‐polarization has been achieved with the transmission coefficients higher than ‐0.66 dB at 3.35 GHz. The performances of designs have been verified by experiments and tests. These designs show potential for breaking the constraints on multiple polarization conversion and promoting the development of versatile PCMs. [ABSTRACT FROM AUTHOR]

This paper presents a novel method to improve the working bandwidth and radiation intensity of piezoelectric antenna by using external circuit. This method makes the piezoelectric antenna combined with roles of high radiation intensity and multiple resonant frequencies without changing the structural size of the piezoelectric antenna. The experimental results show that, compared with the original piezoelectric antenna, the tuning range of the resonant frequency of the piezoelectric antenna caused by the series capacitance and inductance is +13.6 and −24%, respectively. The series inductance will produce new resonance frequency, which provides a new method for the multi-band operation of the piezoelectric antenna. The LLC (series and parallel circuit) composite circuit can increase the number of resonant frequencies of the piezoelectric antenna from 1 to 3, and the S11 at the resonant frequencies are all lower than −10 dB, and the radiated magnetic field of the piezoelectric antenna is increased by 42.3% at least. This method makes the piezoelectric antenna have the dual functions of high radiation intensity and multi-band, which has great significance for broadening the application field of piezoelectric antenna. [ABSTRACT FROM AUTHOR]