In recent years the preferred solution for achieving broadside scanning LWA performance in substrate integrated waveguide (SIW) has been the composite right/left handed (CRLH) leaky wave antenna (LWA). This thesis offers an alternative approach by outlining the design and study of a new periodic LWA architecture that uses half-mode SIW (HMSIW) to feed an array of antipodal tapered slot antenna (ATSA) radiating elements. The new antenna was among the first SIW based periodic LWAs to address the open-stopband that typically hinders broadside radiation, and was the first to do so using a unit-cell matching technique.

Additionally, a compact periodic phase-reversal architecture of the antenna is presented that allows the ATSA element spacing to be reduced, enabling design with a comparatively low substrate permittivity while maintaining grating lobe free scanning. This antenna was the first SIW based LWA to use the periodic phase-reversal technique.