海面反射によるドップラーVORの方位変動の解析
1993 年 1993 巻 78 号 p. 23-33
詳細
1993 年 1993 巻 78 号 p. 23-33
This report describes the mechanism of bearing fluctuation in Doppler VOR (DVOR) by sea surface reflection in order to present an expression for predicting the magnitude of the fluctuation.
Intrinsic bearing error in DVOR is noted to explain the phenomenon. The influence of sea surface reflection on the intrinsic bearing error is analyzed by observing the radiation pattern of DVOR antenna. Then, it has been shown that the bearing fluctuation is caused by the variation of intrinsic error by sea surface reflection. We have assumed that the expression for the intrinsic error may be directly applied to predict the bearing fluctuation.
Flight experiment was performed for several VORs to measure the bearing and signal level. A good agreement between measured and computed results, observed in most VORs, has proved the validity of our assumption. An example is also presented in which measured result did not agree to the computed one. Experimental study has shown that this discrepancy is caused by excessive attenuation of signal level at a null point and that our expression is applicable even in the case by making a slight modification.
The analysis has shown that the magnitude of bearing fluctuation may be reduced if DVOR antenna is designed to reduce intrinsic bearing error, by extending the size of counterpoise for example, because the bearing fluctuation is directly linked to the intrinsic error.
