SIW Based Circularly Polarised Leaky Wave Antenna with Improved Scanning Rate and Scanning Range Using Hairpin-shaped Delay Lines

In this paper, a substrate integrated waveguide (SIW) based circularly polarised (CP) leaky wave antenna (LWA) is designed to increase the scanning rate and the scanning range using hairpin-shaped delay lines. The proposed LWA has unit cells of H-shaped slots followed by hairpin-shaped delay lines placed periodically. This configuration has achieved CP along with frequency beam scanning. The hairpin-shaped delay lines introduce group delay and leakage constant suppression. This leads to an improvement in the scanning rate and scanning range of the LWA. The proposed antenna scans in the frequency range of 11GHz to 12.4GHz with percentage fractional bandwidth of 11.9%. It provides a scanning rate of 60.7 degree/GHz in the scanning range of -10 degree to 75 degree. In addition, a high gain of 14.53dBic at 11.5GHz is achieved.