Measurement of efficiency degradation due to external detuning of a tunable patch antenna

Realistic deployment scenarios for narrow-band mobile terminal antennas can place the antenna in close proximity to sources of detuning such as the user's hand. Undesirable side-effects can include frequency shifts off-resonance and degraded impedance matching, reducing the overall system efficiency. Here, 3D radiation patterns and radiated efficiency measurements were used to evaluate the ability of a tunable matching network to preserve system efficiency in a patch antenna detuned with a hand phantom. The results indicated a trend for improving tuner benefit as a function of increasing severity of detuning. However, the transducer efficiency of 69% — which is a major issue in system evaluation — was too low to justify the improved impedance matching with the degree of detuning examined here.