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A wideband polarization-reconfigurable microstrip antenna based on a mode-fusion mechanism is proposed. This simple antenna structure consists of a rectangular radiation patch and a ground, both with crossed slots. The slots crossing the ground are connected by eight PIN diodes and four capacitors such that two orthogonal linear-polarization radiation modes can be realized. The radiation patch is slotted such that a transformed TM 20 mode is excited, realizing broadside radiation that the traditional TM 20 mode is unable to. With fusion of the fundamental TM 10 mode and the transformed- TM 20 (T- TM 20 ) mode, a wide bandwidth of 30.1% is achieved in two reconfigurable polarizations. The measured results agree well with the simulation results. The total efficiency of the proposed antenna is more than 80.0% over the bandwidth. [ABSTRACT FROM AUTHOR]

A beamwidth (BW) and beam direction (BD) reconfigurable antenna based on multi‐mode parasitic coupling is proposed. Two pairs of metal strips connected by only two positive‐intrinsic‐negative diodes are added as parasitic structures over the driven element, a circular microstrip patch, constituting a simple antenna design. By controlling the diode switching state, four pattern reconfigurable modes can be realised. Two beam‐pointing deflection modes in the E‐plane are realised based on the Yagi–Uda principle. Besides, the BW reconfigurability is achieved due to a joint effect of the Yagi principle and beam‐stacking principle. All the reconfigurable modes share a 10% impedance bandwidth from 5.8 to 6.3 GHz. Simulation and measurement results show that the BW can be switched between 67° and 120° in an omni‐directional plane, and the BD can be switched between 0° and ±30° in the E‐plane. [ABSTRACT FROM AUTHOR]

A compact ultra‐wide‐beam crossed‐dipole antenna for K‐band phased arrays is proposed. The superior wide beamwidth is achieved by loading four vertical parasitic structures around the dipole patches. A quasi‐coaxial feeding structure is proposed as the antenna size is limited in K‐band, and it cannot be coaxially fed by the conventional feeding method. This structure is constructed by using PCB through‐plated vias, achieving a compact design. The antenna has a compact size of 0.37λ × 0.37λ × 0.35λ (λ is the free space wavelength). The simulated and measured results show that a half‐power beamwidth of more than 140° (from −71° to 72°) and an axial ratio beamwidth of 100° (from −51° to 49°) can be realized. [ABSTRACT FROM AUTHOR]