On the efficiency of frequency reconfigurable high-Q antennas for 4G standards

In the actual context of reducing antenna size and operating in multiple bands tunable antennas are investigated. Moreover, high-Q and low-Q tunable antennas are compared with respect to their efficiency. The loss issue that tunable high-Q antennas present is addressed. Using a variable capacitor as a tuning mechanism, simulations and measurements of a self-resonating antenna show the mismatch and the radiation efficiencies of the high-Q and the low-Q antennas. The investigated frequencies are in the low band of the 4G standard. Measurements are conducted for different tuning stages and the study shows that the high-Q design performs worse than the low-Q one. A 1.4 dB degradation in total efficiency is observed for a high-Q antenna in a tunable system.