Design of Miniaturized Active Matching Network Integrated Ultrabroadband VHF/UHF Monopole Antenna for Direction Finding Array Applications

This letter proposes a novel active very high frequency/UHF monopole antenna for location and direction-finding applications. A non-Foster active matching network (AMN) drives the designed ultrabroadband monopole's input for the enhancement of exclusive bandwidth operating from 60 MHz to 1.31 GHz (182.48% fractional bandwidth) with a 6 dB minimum return loss. Double-stage low noise amplifier (LNA) is cascaded with AMN for the gain enhancement (>= 40 dB) over the operating band. The AMN-integrated monopole is extremely compact and ultraminiaturized, with dimensions of 0.032 lambda(L) x 0.044 lambda(L) at 60 MHz. The measured results are in good agreement with the simulations. The authors believe that the ultrabroadband active monopole is one of the promising solutions for antenna arrays employed in direction-finding applications.