Quality Factor Comparison of Coaxial-Fed and Edge-Fed Electrically Small Microstrip Antennas

This letter presents and discusses the simulated and measured values of Q for microstrip antennas with different feeding schemes (edge-fed versus coaxial-fed) for regular (rectangular) and electrically small (meandered) designs. The edge-fed antennas are not matched, while the coaxial-fed are matched to 50Ω. The measured Q is compared to that given by exact and approximate formulas, simulations, and the Chu lower bound. The objective is to assess by how much a measurement of Q typically differs from its anticipated value, in regular and miniaturized microstrip antennas for different feeding schemes.