Printed-circuit antennas for ultra-wideband monitoring applications

Two new printed-circuit antennas for ultra-wideband (UWB) monitoring applications are introduced. Both microstrip and coplanar waveguide antennas operate between 3 GHz and 30 GHz with a return loss of 10 dB. The vertically polarized omnidirectional radiation characteristics in the lower frequency band change to a more directional pattern at higher frequencies. The cross-polar field component increases with frequency and gives rise to possible dual-polarized applications for the microstrip antenna. Overall, the coplanar antenna shows slightly better performance. Amplitude and group-delay responses are demonstrated over the entire 3-30 GHz band, and radiation patterns at selected frequencies are shown.