Broadband Tuning of Mobile Terminal Antennas

In this paper, broadband frequency tuning of mobile handset antennas using switches and passive reactances is studied. The idea is applied to a compact coupling element antenna, for which a dual-band (E-GSM900 and GSM1800) tuning circuit is designed and prototyped. The objective was to have a sufficient impedance bandwidth and good efficiency. The 6-dB bandwidth requirement is fulfilled at both frequency bands and the measured maximum total efficiency at both frequency bands is about 50%. Using better switches and an optimised tuning topology could still improve efficiency. However, the results of the study indicate that broadband tuning of small antennas is possible.