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
λ_L
× 0.044
λ_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.