Substrate integrated waveguide circularly polarized horn-dipole antenna with improved gain

A substrate integrated waveguide (SIW) horn antenna is combined with a dipole to achieve circular polarization (CP). First, it is established that CP can be achieved by combining a horn and a dipole. To excite the dipole, double-sided tapered and balanced transmission lines are employed at the central part of the horn aperture. Secondly, after the position and the size of the dipole are determined, a directional circularly polarized beam in the plane of the substrate is achieved. Finally, the proposed antenna is fabricated and measured. Experimental results are in good agreement with simulations. Measured results show that an effective bandwidth of 5% for axial ratio (AR) less than 3 dB and return loss (RL) better than 10 dB from 11.8 to 12.4 GHz is achieved. In particular, the maximum gain of the proposed antenna is as high as 7.5 dBi due to the design of the horn structure. (c) 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2973-2977, 2016