Evaluation of wheeler cap antenna efficiency measurement methods using numerical EM simulation data

The paper presents the two port efficiency method produces loss numbers that are in the best agreement with the direct normalized loss simulation results. The series circuit model loss gives approximately correct numbers for the monopole antenna while the parallel circuit loss calculations are highly inaccurate. However, it is interesting to note that for other two antennas, the series circuit calculations are substantially inaccurate while the parallel circuit calculations are approximately correct. The monopole antenna shows a S₁₁ trajectory on the Smith Chart that approximates a series resonant circuit as a function of frequency. The PIFA and microstrip patch antennas show an S₁₁ trajectory that approximates that of a parallel resonant circuit. This author believes that the S₁₁ trajectory as function of frequency is an important factor in deciding which equation to use, if one chooses not to use the most accurate of the three methods, the two port efficiency calculation method.