Millimeter-Wave Leaky-Wave Antennas Based on Polymer Rod with Periodic Annular Metal Strips

Leaky-wave antennas based on a polymer rod, operating at Ka-frequency band, are presented. A periodic pattern of 50 annular metal rings is applied to the polymer rod, resulting in a radiation pattern scanning with frequency. The antennas are operating either in the fundamental HE11 mode or in the rotationally symmetric TM01 mode, the latter resulting in omnidirectional radiation pattern. The antennas are fed via transitions to rectangular waveguide and coaxial waveguide, respectively. The designs are verified by measurements. Operating in HE11 mode, a gain between 12 dBi and 18 dBi is measured at frequencies from 27 GHz to 40 GHz, while scanning over 55 degrees angle in direction. The peak frequency scanning resolution amounts to 8.3 degrees per GHz. Operating in TM01 mode, a gain between 12 dBi and 16 dBi is measured at frequencies from 33 GHz to 40 GHz, while scanning over 34 degrees angle in direction. The peak frequency scanning resolution is 6.5 degrees per GHz.