The Solution Of End Effects Of Slot Line By Open Cavity Method

Abstract

ABSTRACT An open cavity model is developed to analyse end effects of slot line. Both the reactance and radiation effects are taken into account. The nu­ merical results are compared with the published data.INTRODUCTIONSlot line is a transmission medium for micro­ wave and millimeter wave applications. Much work has been done for its guided-wave properties [1] [2]. Only few work, however, has contributed to its discontinuities, such as step or shorted end. A slot line shorted end is needed to build slot line transitions or filters. As far back as 1973, ex­ perimental characteristics of a slot line shorted end have been reported by Knorr et al [3]. Until last year no theoretical work was presented. Yang et al [4] [5] reported their results about slot line shorted end by dynamic model.In this paper an open cavity model is presented for analysing shorted end of slot line. The reac­ tance and radiation effects are both considered. The numerical results show that the reactance parts of the end effects by cavity model agree well with that in [4] [5] and radiation resistances are different from that in [5].CAVITY MODEL FOR SLOT LINE SHORTED ENDThe slot line cavity is shown in Fig. 1, which is composed of a uniform slot line with two shorted ends. The equivalent circuit for it is shown in Fig. 2. As well known, resonance frequency of this cavity is a complex value, because of radiation losses, and can be denoted ascO = cor + ju>^where o)r is the oscillation frequency of the cavity. ^ stands for losses.For a half-wave cavity the normalized equiva­ lent reactance can be found from following expres­ sionX= jwhere 6 is the propagation constant at 6) = k)r for uniform slot line.L1 = ^The radiation resistance R can be found by following procedure.It is known that the power losses caused by radiation from one end in this cavity can be written as