Numerical study of waveguide endwall slot feed microstrip arrays

An initial numerical study of a 4×4 microstrip array excited by a rectangular waveguide endwall slot is described. This design is a candidate for an LMDS subscriber equipment antenna. Direct coupling via a slot avoids the use of a probe, which prior investigators have shown to be detrimental to manufacturing yield at LMDS band. Tapering the short sides of the rectangular waveguide feed is shown to improve the input impedance matching here, with the optimal taper length being about λ_g/2. The input impedance bandwidth was 5.2%