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

This work proposes a novel active VHF/UHF monopole antenna for location and direction-finding applications. A nonfoster 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. Doublestage LNA is cascaded with AMN for the gain enhancement (≥ 40 dB) over the operating band. The AMN integrated monopole is extremely compact and ultra-miniaturized, with dimensions of 0.032λL×0.044λ 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.