3-D corner reflector antenna and its analysis using UTD

A 3-D corner reflector antenna consists of three planar reflectors and a 3/4/spl lambda/(/spl lambda/ is the wavelength) monopole located on one of the reflectors as shown. The idea of this antenna was first proposed by Inagaki (1974) in which it was reported that the gain is about 5 dB greater than that of the conventional 2-D corner reflector antenna, and that the input impedance is between 50 /spl Omega/ and 75 /spl Omega/ which is adequate for direct feed by coaxial cables. But this analysis was based on image theory and EMF method, and sidelobe suppression was evaluated in only an approximate manner. This paper calculates the radiation pattern accurately with diffracted fields evaluated by the UTD. Moreover it is demonstrated through a detailed analysis that a higher order mode structure using a 5/4/spl lambda/ or a longer monopole instead of a 3/4/spl lambda/ monopole exhibits higher directivity while the sidelobe level being kept lower than -20 dB.<>