Antennas and propagation-retrospective and prospective views

A review which attempts to look both backwards and forwards over twenty years is of necessity imprecise, the more so with the forward look. Nonetheless even in the forward look the lead-time for some systems which incorporate antennas is of the order of twenty years and the collection of propagation data is nearly always long term. We stand at the threshold of satellite mobile systems such as IRIDIUM, GLOBALSTAR, ODYSSEY and INMARSAT-P with TELEDESIC to follow. The antenna requirements for most of these systems would have seemed daunting twenty years ago and there still exists a lack of relevant propagation data. This will change once these systems operate in the late nineties and early years of the next century, so providing the propagation community with a feast of new results. The author also identifies some of the highlights of the antenna technology of the last twenty years and relevant developments in propagation, beginning with reflectors, feeds, direct radiating arrays and microstrip antennas.