Investigation of parasitic effects from feed and termination on the far-field pattern of leaky-wave antennas based on HMSIW

In this paper the parasitic effects from the feed and termination on the far-field pattern of two types of leaky-wave antenna (LWA) based on Half-Mode Substrate-Integrated Waveguide (HMSIW) are thoroughly investigated. It is shown that the ripples observed on the radiation patterns originate from the discontinuities in the aperture field distribution, which typically appear at the feed and termination of the antennas. The paper will firstly focus on explaining the ripples on the pattern of a wideband omni-directional antenna based on a tapered HMSIW by studying the field distribution in the vicinity of this antenna. Then the ripples in the highly directive pattern of a uniform LWA are analyzed and compared. The understanding gained from this study can assist to develop techniques to reduce ripple level in the pattern of these types of LWAs.