Circularly-polarized microstrip antenna radiation efficiency simulation based on the wheeler cap method

The simulation of the radiation efficiency of CP truncated-corner microstrip antennas is reported in this paper. The application of the Wheeler cap method to TCSMA radiators is only good for estimation purposes, with errors around 10%. However, for the alternate TCRMA topology, designed to operate at the Xin = 0 condition, the Wheeler method provides excellent results, with errors less than 1%. Although the amplitudes of the antenna resonant modes do not vary significantly by increasing the cap dimensions, the frequencies will tend to their free-space values. Consequently, to prevent the excitation of undesirable modes in the cavity, large structures must be avoided.