Wire monopoles are commonly deployed on vehicles in ground-based mobile communication systems since these antennas have omnidirectional (in azimuth) field patterns and linear polarization. Broadband antennas are attractive for use with multi-band radios and transmitters implementing spread spectrum modulation techniques over wide bandwidths. Antennas that are inherently broadband include spirals and axial-mode behest. However, these antenna have inherently polarization with end-flee field patterns. Log-periodic antennas are also inherently broadband and are linearly polarized. Yet, these do not meet the omnidirectional requirements. Thus, bandwidth improvement is pursued of the inherently narrowband which exhibits suitable radiation characteristics for the applications mentioned above. In [l]-[2], a monopole antenna is loaded with three parallel inductor-resistor circuits and has an ideal lossless matching network consisting of a transformer, shunt inductors, and series capacitors. Although no measured results are presented in [1]-[2], the numerical results indicate voltage standing wave ratio (VSWR) less than 3.5 and system gain greater than -5.5 dBi over a 25:1 bandwidth (20 - 500 MHz). In this paper, the system of [l]-[2] is simplified and re-optimized over a 15:1 bandwidth in order to pursue a physically realizable design. Measured results of a constructed antenna and matching network indicate a bandwidth ratio of 12.6; 1 [3].
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