Miniaturized Super Wideband VHF/UHF Monopole Antenna With Integrated Matching Network for Spectrum Monitoring Applications

This paper presents a novel, extremely low-profile, miniaturized monopole antenna for spectrum monitoring applications. The antenna achieves an unprecedented 100:1 impedance bandwidth (30–3000 MHz), corresponding to a fractional bandwidth of 196%, with a compact size of $0.03\lambda \times 0.03\lambda \times 0.00015\lambda$, where $\lambda$ is the wavelength at the lowest operating frequency. To address size, weight, and power (SWaP) constraints while extending operation into the challenging 30–300 MHz band, a multi-stage lumped-element matching network is integrated on the antenna's back side. This dual-path matching network enables Ant. 5 ($0.03\lambda$) to match the low-frequency performance of a much larger antenna (Ant. 4, $0.24\lambda$), effectively overcoming the size-bandwidth limitation. The antenna achieves a peak gain of 3.6 dBi at 800 MHz and maintains gain above 0 dBi from 360 to 3000 MHz. Measured VSWR remains below 3 from 30 to 38 MHz and below 2 across the remaining of the operational band. Simulated and measured results show excellent agreement, validating the design's suitability for SWaP-constrained platforms such as mobile, airborne, and densely deployed systems. This study offers a transformative solution for broadband spectrum monitoring and direction-finding arrays.