Propagation along periodic monopole arrays

Many successful, practical and useful designs have evolved from the log-periodic class of frequency independent antennas in the past few years. One such is the vertically polarized log-periodic monopole array which, because of its geometry, must be considered as a separate class. Because of reduced height requirements (approximately one-quarter wavelength), these antennas have found wide application in the few years of their development. For every successful design, however, there have been at least several unsuccessful attempts. This is evidence that a thorough knowledge of the basic principles which underlie successful frequency independent performance does not yet exist. This fact, and the requirement of the sponsoring agency for an improved vertically polarized directional antenna system for wideband operation, prompted the subject study.