Influence of Unconventional Erect Counterpoise on Radiation Performance of DVOR System

‍ ‍The counterpoise is an important component of the Doppler very high frequency omnidirectional range （DVOR） antenna system， with a conventional height and diameter of approximately 5 m and 30.5 m respectively. With the continuous development of urbanization， the environment of DVOR beacons is rapidly deteriorating. Some civil aviation units are attempting to increase the height and diameter of the counterpoise simultaneously to reduce the impact of surrounding buildings on the radiation performance of DVOR beacons. However， there was a lack of theoretical analysis of the impact of these unconventional counterpoise on the radiation characteristics of DVOR beacons， and there was lack of theoretical guidance for the installation of such counterpoise. Based on the antenna characteristics and feeding characteristics of the DVOR system， the DVOR radiation electric field， including direct radiation electric field， ground reflection electric field， and counterpoise scattering electric field， was obtained using physical optics method. On this basis， according to the requirements of Annex 10 of the International Civil Aviation Organization （ICAO）， the DVOR beacon upper space of silence during unconventional counterpoise installation was given， And the solution method for the electric field strength distribution within the farthest horizontal coverage distance corresponding to different flight altitudes， and corresponding simulation experiments were conducted. The experiment results showed that if the diameter of the counterpoise is maintained at a conventional 30.5 m， the vertical radiation characteristics of DVOR beacons with unconventional high counterpoise will not exhibit multi lobe phenomenon， and the upper space of silence will not be affected. The field strength within the farthest horizontal radiation distance corresponding to different flight heights specified by ICAO meets the requirements； But when the counterpoise height increases to 30 m or more， even if the diameter of the counterpoise is increased to 50 m， it is difficult to meet the horizontal coverage field strength requirements specified in Annex 10. The research results can provide corresponding theoretical support for the construction of unconventional counterpoise DVOR beacons.