Transactions on Antennas and Propagation
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| A. Equivalent transmission line theory and the expression of radome insertion phase delay (IPD) In this work, the tangent-ogival radome proposed in [8] is employed for simulation, and accordingly, the D ray-tracing method used in [8] is adopted to evaluate the radome performance parameters. Similar with the inhomogeneous planar layer (IPL) radome which is considered as a cascade of many thin homogeneous planar layers, streamlined inhomogeneous radome is considered as a cascade of many thin homogeneous layers with the same streamlined shape. Using ray-tracing method, the normalized far field of the antenna-radome system (cf. Fig. 1) is given by [8] ( ) ( , ) ( , ) x y z j k x k y k z M S S E x ye iiT ds F E x y ds (1) where ( , ) E x y is the aperture field, T M is the co-polarized transmission coefficient, and S denotes the antenna aperture. The transmission coefficient T M for linear polarization can be calculated using the equivalent transmission line theory [20] in the following form cos sin M H V T T T 2 (2) where T H and T V are the parallel and perpendicular polarization transmission coefficients, respectively, and is the polarization angle, which lies within [0°, 90°]. T H and T V depend on the radome thickness, permittivity, incident angle and frequency. In this study, similar with the method in [6] and [8], mutual interactions are not included in the EM performance analysis of X (c) 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information DOI TAP, IEEE Transactions on Antennas and Propagation > REPLACE THIS LINE WITH YOUR PAPER IDENTIFICATION NUMBER (DOUBLE-CLICK HERETO EDIT) < 3 inhomogeneous radomes, which is justified by the extremely low reflection realized by the impedance match effect of in- homogeneous radomes. Fig. 1 Antenna-radome system. d 1 , d 2 ,… d m are the thicknesses at m selected points used to interpolate smooth thickness profile. T M , T H and T V are complex numbers, which can be written in terms of the magnitude and the phase. In this way, (2) can be rewritten in the following form 2 cos sin V M H j j j M H V t e t e t e (3) where, for i=M, H, V, t i represents the amplitude of the complex number T i , i represents the phase of T i which is known as IPD. What is concerned is the IPD of T M , i.e., M , referred to as radome IPD in the following, as it directly determines the ra- dome BSE. It is of significance to find the relationship between M and H , V . Fig. 2 shows the sum of two complex numbers, where the angle between the complex vector and the real axis represents the phase. It can be seen that the phase of the sum is between that of the two additive complex numbers, and is closer to the phase of the complex number which has the larger amplitude. Fig. 2 The addition of two complex numbers. In (3), Download 1 Mb. Share with your friends:
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