A Wideband Circularly Polarized Horn Antenna using Transmission Type Linear to Circular Polarization converter for Ka-band Applications

In this paper, a wideband circularly polarized horn antenna operating in Ka-band is proposed. A multi-layer frequency selective surface-based wideband transmission type linear to circular polarization converter is integrated with a Ka-band standard gain linearly polarized (LP) horn antenna to arrive at a circularly polarized (CP) horn antenna design. The polarization converter (PC) consists of four layers of FR4 substrate, each of 20 mil thickness with a horizontal metallic strip printed on one side. The overall size of the PC is 0.37 lambda(o) x 0.37 lambda(o) x 0.65 lambda(o) (lambda(o) corresponds to the wavelength at 26.5 GHz). A 62 x 62 array of the unit cell of the PC is fabricated and integrated with the Ka-band horn antenna. The LP horn antenna with the PC shows a 3-dB axial ratio bandwidth of 30.4% (26.5 to 36 GHz) in measurement. The measured gain of the circularly polarized horn antenna ranges between 10 dBiC to 13.2 dBiC in the operating frequency band.