Comments on "Couple-mode analysis for nonuniform crossed-field drift beams"

Abstract

Howes [l] has described the effects of the encapsulation on Gunn device performance, and has derived theoretical tuning characteristics from an analysis of the microwave circuit. We have carried out similar studies, and obtained results that differ in certain respects from those of Howes. Our results will be briefly summarized here, with comments on the reasons for the apparent discrepancies. Like Howes, we have derived the input impedance of the packaged Gunn device, although we have employed the results of the detailed measurements on the S4 microwave package that are reported upon elsewhere [2]. We find three resonances that in order of increasing frequency are series, parallel, and series. The input impedance of the package may now be equated to the complex conjugate of the input reactance of the waveguide resonator combined with the load resistance. It is important to decide whether the load is in series or in parallel with the resonator, since close to the package resonances the solutions for the waveguide cavity length are entirely different-the resonance condition may be met either with a low reactance in series with a resistance, or by a high reactance in parallel with a resistance. It is on this point that our studies differ from those of Howes. The analysis given by Howes implies a load resistance in series with the resonator. R‘e suggest that this is inconsistent with his microwave circuit, which is more appropriately represented by the parallel load configuration. This approach is supported by the work