Restoration of the RET Phase Function Using Deconvolution

Abstract

The influence of vegetation has become an important aspect of the design of wireless communication links. In recent years theory of Radiative Energy Transfer (RET) has been adapted as a reliable tool to predict the radiowave propagation through and near vegetation. The developed RET prediction model requires 4 input independent parameters, which so far had to be established from one measurement only, thus limiting their accuracy. An independent measurement which is termed the phase function can readily yield 2 of the 4 input parameters independently, which significantly increases the accuracy of these parameters. However one major factor influencing the phase function measurement is the radiation pattern of the receiving antenna. The measured curve will be the result of the convolution of the antenna radiation pattern and the phase function of the vegetation medium. The measurement curve therefore needs to undergo a deconvolution process before any RET input parameters can be derived from it. This paper presents the deconvolution method developed using optimal compensation deconvolution methods. Deconvolution is demonstrated using both simulation signal shapes and those measured in vegetation set up in the anechoic chamber. This paper discusses different cases of optimal compensation filtering with the relative curves shown.