Low-Profile Two-Arm Inverted-L Antenna Design for Vehicular HF Communications

Design of an electrically small, low-profile vehicular on-the-move (OTM) wideband high frequency antenna with 24 kHz instantaneous-tuned bandwidth is discussed for near vertical incidence skywave (NVIS) communications. Improvement in performance is obtained by applying multiarming and offset feed antenna modifications. These allow for attaining the desired gain >-20 dBi at 3 MHz with a lower profile compared to traditional OTM 3 kHz bandwidth antennas. Specifically, the addition of the second arm improves the bandwidth, whereas NVIS gain is enhanced by offset feeding. The electrical dimensions of the proposed two-arm design over the platform are λ/13 (L) × λ/30 (W) × λ/400 (H) at the lowest frequency of operation. Antenna performance and achieved benefits under the condition of mechanical breakdown are also discussed. The scaled prototype of the proposed antenna mounted on a selected vehicular platform is built using additive manufacturing. Measurement results agree well with simulations thereby verifying the design procedure and all the discussed findings.