Wideband low‐profile null‐filled monopole antenna for aircraft flush‐mount applications

A wideband low‐profile null‐filled monopole antenna for aircraft flush‐mount applications is presented. The antenna consists of a semicircular monopole and a direct‐fed dual loop in a flanged cylindrical cavity. The zenith null in the monopole radiation pattern is filled by horizontal currents of the dual loop. Measurement shows that the proposed antenna has a reflection coefficient of <−10 dB over 4.53–7.43 GHz, 6.45 dBi maximum gain, −0.8 dBi filled null depth and a −3.7 dBi minimum horizontal gain at 6 GHz.