Summary
International Symposium on Antennas and Propagation
2008
Session Number:3C21
Session:
Number:3C21-3
How Far is Good Enough for the Far-Field Pattern?
K. Hirasawa, T. Arima, T. Uno, H. Morishita,
pp.-
Publication Date:2008/10/27
Online ISSN:2188-5079
Summary:
In the measurement of far-field patterns it is important to keep the enough distance r between a test antenna and a probe antenna [1]-[3]. As the far-field condition it is well known that r should be greater than rf (= 2D 2 /λ) where D is the largest dimension of the physical aperture of a test antenna as shown in Fig. 1 and changes with the location of the rotation center of the test antenna. In this paper we show how the pattern changes with r for two kinds of antennas by using a moment method computer program [4]. One is with the minimum D larger than λ (an eight element linear array). The other is with the minimum D smaller than λ (a monopole antenna on a rectangular conducting plate that is a model of a portable radio). Patterns are calculated for two different rotation centers of each antenna and the necessary r for the far-field pattern is investigated.