3-D-Printed Spiral Inverted Ridge Circularly Polarized Horn Antenna with One Octave Bandwidth

This letter presents a novel 3-D-printed spiral inverted ridge horn antenna with excellent broadband circularly polarized (CP) performance in the frequency range of 8 GHz to 16 GHz. For the first time, a circled dash-shaped inverted ridge is proposed to enhance the bandwidth of the circular waveguide. Through careful investigation of the propagation characteristics of the proposed inverted ridge, it has been found that, in order to achieve high-performance circular polarization over one-octave bandwidth, the total length of the spiral inverted ridge should be one guided wavelength of the lowest operating frequency. 3-D printing technology is utilized to manufacture the proposed antenna for the desired geometric complexity. The measured results validate the accuracy of simulated results, with a measured axial ratio (AR) of less than 1.5 dB and a reflection coefficient of less than -14 dB from 8 GHz to 16 GHz. Moreover, the measured 3 dB beamwidth of the radiation pattern remains stable between 41° and 70°.