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Designs of 1 × 4 vertically polarized arrays with wide beamwidths are described. The array is composed of two pairs of monopole slot antennas, and each pair is excited with a differential feed scheme to reduce cross polarization. In addition, a rectangular metallic box is introduced as a reflector of the array to generate different beamwidths and improve front‐to‐back ratios. From the simulated results, it is found that by tuning the dimensions of the metallic box, the H‐plane half‐power beamwidth of the array can be varied between 90° and 180°. For each beamwidth case, the 10dB‐return‐loss bandwidth (BW) of the array can cover the band from 1.7 to 2.7 GHz; moreover, a cross polarization of lower than −20 dB, a front‐to‐back ratio of higher than 15 dB, and a beamwidth variation of <10° are also realized within the impedance BW. An experiment is also carried out to validate the simulation. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2871–2876, 2016

A simple design for circularly polarized (CP) patch antennas with broadband operation is presented. The design is based on a cross slot antenna with an ellipse-shaped ground plane. A design guideline for the CP antenna is given. Three samples are performed by the guideline, and their antenna prototypes are fabricated and tested. Measured results show that the 3dB-axial-ratio bandwidths of the three prototypes, centered at 0.9, 1.4, 2 Hz, are 26, 37, and 33%, respectively. In addition, the performances of the slotted patch antenna backed with a reflector are also addressed.

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A design for quad‐polarization‐agile antenna is described. A multiport crossed dipole that can provide dual orthogonal linear polarizations is used as the radiating element of the design. When the crossed dipole is fed with a tunable power divider, the two linear polarization radiations can be simultaneously excited with same amplitudes and difference phases. The resultant polarization modes include ±45° linear polarizations, right‐handed circular polarization, and left‐handed circular polarization. The overlapped operation bandwidth of the four polarization modes is about 49%, and the antenna operating in each polarization mode has almost the same radiation patterns. These patterns are also stable against frequency. Moreover, the occupied area of the polarization reconfigurable antenna is about 0.43λ0 × 0.43λ0.