A study of optically tuned metallodielectric photonic band gap array and patch antenna

A novel optical tunable 1-D metallodielectric photonic band gap (MPBG) device, which achieved a 50% bandwidth and 2:1 frequency tuning, has been demonstrated. Whereas sufficient bandwidth can be obtained with the MPBG structures, for applications that require adaptive processes, a dynamically tuned MPBG would be required. We present for the first time results from an optically tuned dipole MPBG. We have applied a similar optical technique to a patch antenna incorporating an optically controlled microswitch in series with the patch feeding line which, operates in the bandgap. We pay attention to the coupling across the gap of the switch, which is a key factor for the impedance match and switching performance. We introduce some techniques that we have previously developed for the switching of microstrip lines by utilising a silicon substrate under optical illumination. Use is made of the photoconductive properties of the silicon in order to bridge a physical discontinuity in a line. We present results for both S11 and the boresight gain of the antenna and its switch. We also investigate the practical ways of avoiding unnecessary loss of power, and coupling effects across the gap of the switch