Design techniques for circular aperture antennas

The far field radiation patterns, of two distinctly different circular aperture antennas are analyzed. The first of these is a special type of quasi-ring array--the towel bar array of N elements, where N is an even number. It is shown that the complete set of model radiation patterns can be characterized in the form of a set of very simple algebraic expressions. Further, it is shown that there is an N/2th order degeneracy. An example is given for the case of a six element towel bar array. In addition, techniques are introduced for the synthesis of planar circular apertures to achieve highly directive radiation patterns which admit the arbitrary control of the heights of specific sidelobes. An illustrative example shows that, using these techniques, the desired sidelobe topology can be achieved in a practical design.