Printed bowtie antenna fed by electromagnetic coupling

Printed planar antennas are widely used in many current applications. One of the main limitations is their narrow bandwidth. To improve this last parameter, several shapes have been studied, namely: bowtie, spiral, logarithmic antennas, ... The investigated results indicate that the radiating performances are influenced, as expected, by the dielectric substrate, the radiating element shape and the feeding circuits. In the present research, printed bowtie antennas fed by electromagnetic coupling from an embedded microstrip line are investigated, An impedance transformer circuit is optimized and the obtained performances are compared to those given by a simple 50 /spl Omega/ microstrip line. Measurements of return loss and radiation patterns are also presented and compared to the calculated ones.