Optimization of ultrawideband bow-tie antennas for cable based operation

In this paper we present the design and optimization of an ultrawideband bow-tie antenna for the operations on top of a coaxial cable. The shape of the antenna is derived from canonical analytic equations. In order to reduce parasitic currents on the shielding of the cable caused by the unbalanced transition between the unsymmetric coaxial feed and the symmetric planar radiator the lower plate of the bow-tie is designed to operate as a sleeve in addition. The antenna is shown to be less sensitive to the coaxial cable compared to simple configurations without the sleeve. The study is based on numerical simulations using the FDTD simulator EMPIRETM.