Title :
Radiation characteristics of a ship-mounted high frequency ground wave radar antenna
Author :
Anstey, M. ; Saoudy, S.A.
Author_Institution :
Fac. of Eng. & Appl. Sci., Memorial Univ. of Newfoundland, St. John´s, Nfld., Canada
Abstract :
Ship-mounted groundwave radar (GWR) systems can be used to detect over-the-horizon icebergs, ships and low flying aircraft. Due to space limitations, vertical quarter-wave monopoles mounted on top of the irregularly shaped conducting ship structure or half-loop monopoles mounted on either side of the ship´s side hull are usually considered good candidates for this application. Both the moment method and the geometrical theory of diffraction are used to calculate the in situ far field radiation patterns of these two types of GWR antennas. The objective of this investigation is to evaluate the far field radiation pattern taking into account all field components including geometrical optics, diffraction produced by surrounding edges and corners and dominant diffraction/reflection interactions. The results indicate that the ship´s geometry can have a considerable impact on the radiation patterns of its on-board antennas. For example, the omnidirection horizontal radiation pattern of a vertical whip monopole over a perfect ground can be deformed to a pattern with a 17/spl deg/ beam width main lobe and a 15 dB front-to-back ratio for specific locations on the ship.
Keywords :
antenna radiation patterns; electromagnetic wave reflection; geometrical optics; geometrical theory of diffraction; loop antennas; method of moments; monopole antennas; radar antennas; ships; corner diffraction; dominant diffraction/reflection interactions; edge diffraction; far field radiation patterns; field components; front-to-back ratio; geometrical optics; geometrical theory of diffraction; half-loop monopoles; hull; irregularly shaped conducting ship structure; low flying aircraft; moment method; omnidirection horizontal radiation pattern; onboard antennas; over-the-horizon icebergs; perfect ground; radiation characteristics; ship geometry; ship-mounted HF ground wave radar antenna; vertical quarter-wave monopoles; vertical whip monopole; Airborne radar; Aircraft; Antenna radiation patterns; Frequency; Geometrical optics; Marine vehicles; Moment methods; Optical diffraction; Physical theory of diffraction; Radar detection;
Conference_Titel :
Antennas and Propagation Society International Symposium, 1996. AP-S. Digest
Conference_Location :
Baltimore, MD, USA
Print_ISBN :
0-7803-3216-4
DOI :
10.1109/APS.1996.549965