The use of high-impedance surfaces (HISs) to increase
the frequency-scanning sensitivity of hollow leaky-wave
antennas (LWAs) is presented. The LWA consists of a hollow
rectangular waveguide with one of its narrow walls replaced by
a partially reflective surface, and it is loaded with a metallodielectric
HIS to increase its beam-scanning response. Theoretical
results based on a simple transverse equivalent network illustrate
the physical mechanism responsible for the improvement, and
they are verified by experiments on a prototype working in the
11–16 GHz band.