Synthesis of circularly polarised multiprobe feed radial line slot array

In previous articles, we presented an easy way to analyze a slot array fed through a radial line and the design of an array of slots placed in an Archimedes spiral. The analysis was based on a circuit approach where the circuit parameters have been estimated using the first propagation mode in the radial line and the far field theory. The Archimedes spiral design, obtained with only one probe, has an efficiency problem due to the reflected field, that can be solved with this multiprobe design. The paper describes the antenna design method, giving the slot position and angle to obtain a radial line slot antenna having circular polarisation and broadside main beam.