Low-Profile Tri-band Inverted-F Antenna for Vehicular Applications in HF and VHF Bands

摘要

A low-profile tri-band inverted-F antenna (TIFA) is proposed for narrowband vehicle-based applications in upper HF and lower VHF ranges. A driven element, engineered as an inverted-F antenna, operates at the lowest frequency of 27 MHz, while two parasitic elements, built as inverted-L monopoles, enable resonances at 49 and 53 MHz. The standalone antenna height over a ground plane is 5 at the lowest band. When mounted on a vehicle and bent to follow its profile, TIFA maintains similar performance with only height above the vehicle’s roof. To eliminate the need for external matching network, the driven element is offset fed. The bandwidth of the first band is greater than 1%, whereas the bandwidths of the two VHF bands are narrower and do not exceed 0.4%. To mitigate possible detuning and enable full utilization of the FCC approved bandwidths, a simple approach for tuning the resonance is outlined. Scaled models of TIFA and vehicle are built and impedance and pattern measurements are conducted. Obtained results confirm the proposed antenna is a viable candidate for (among other applications) communication with remotely controlled ground and flying vehicles/toys.