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.

A design for the antenna with equal beamwidths in two orthogonal planes is described. The antenna is mainly composed of a printed dipole fed with a microstrip balun and a rectangular metallic box used as a reflector. The simulated results obtained with HFSS demonstrate that the beamwidths of the antenna in the E‐ and H‐planes as well as the diagonal plane are almost the same within the 10 dB‐return‐loss bandwidth from 2.3 to 3.3 GHz; moreover, the cross polarization in these planes is lower than −20 dB. The spherical vector wave expansion of the radiated fields of the antenna is used to explain the radiation characteristics. An antenna prototype is also constructed, and experimental data have good agreements with the simulation results.