Analysis of course errors on CVOR antennas (including effects ofmutual coupling between elements)

摘要

A VHF omnidirectional radio range (VOR) is a navigation aid radionbeacon facility, which provides aircraft with azimuth informationnrelative to the VOR station in question as the origin. In Japan, twontypes of VOR-the conventional type (referred to as a CVOR) and thenDoppler type (referred to as a DVOR)-are currently in use. An elementnknown as the Alford loop antenna (ALA), which changes the loadingnreactance, is used for the VOR because the horizontally polarized wavenand nondirectivity in the horizontal plane are preferred. A VOR antennanconsists of a carrier antenna and a sideband antenna-an aircraftnreceives separate signals from these two antennas and compares them tonobtain azimuth information. The mutual coupling between the elementsnforming the carrier and the sideband antenna affects the directivity ofnthe single elements, resulting in errors in azimuth information. Withnthe mutual coupling between the antenna elements being taken intonconsideration, a quantitative calculation was made by using the momentnmethod-the results of the calculation made it clear that a loadingnreactance value of -320 Ω is better to make not mutually couplednelements nondirectional while a loading reactance value of -600 Ωnis optimum to minimize the azimuth error of a CVOR