Dual-polarized K/Ka-band planar log-periodic antenna

This paper demonstrates an 18–40GHz four-arm planar log-periodic antenna with integrated wideband hybrid fabricated using printed circuit board (PCB) process. The two orthogonal linear polarizations are obtained by exciting the log-periodic structure with two microstrip lines perpendicularly oriented in two PCB layers. Two circular polarizations are obtained by monolithically integrating a quadrature hybrid with the antenna. The antenna with hybrid achieves return loss greater than 11dB, gain around 3dBi, and good radiation pattern consistency throughout the bandwidth.