Electronically reconfigurable cellular radio multicouplers

The use of frequency agile transmitters is considered advantageous in two different contexts, namely frequency hopping to combat fading in digital cellular systems, and dynamic frequency assignment to increase efficiency in analogue systems. It is believed that the transmitter combiners remain the only section of the hardware system requiring attention in practical realization of such schemes, if the low loss and good linearity performance of a high selectivity approach is to be utilized. Various techniques are available for the rapid remote tuning of resonators, using ferrite spheres or discs, or varactor diodes for continuous variation, or switching via the use of PIN diodes. The authors have investigated a number of schemes utilising the above techniques, specifically aimed at preserving the necessary high unloaded Q of the combiner resonators