Fourier-transform scattering analysis for waveguide T-junction and notches in a waveguide

Abstract

A solution for waveguide T-junction is obtained in analytic series form. The T-junction plays an important role in microwave circuits such as power dividers and multiplexers used in modern communication systems. We introduce a new boundary plane to solve the fields in junction. A Fourier-transform technique is employed to express the scattered field in the spectral domain in terms of parallel-plate waveguide modes. The simultaneous equations are solved to obtain the transmission and reflection coefficients in simple series forms. H-plane waveguide T-junction can be analyzed by two dimensional modeling. Chapter 1 explains the scattering behaviors in H-plane T-junction. Comparisons between our solution and experimental results show the excellent agreements. In Chapter 2, we solve the E-plane waveguide T-junction problem by two dimensional analysis. Chapter 3 explains three dimensional analysis for E-plane waveguide T-junction, and compares the difference between H-plane and E-plane waveguide T-junctions. In Chapter 4, the problem of scattering from the finite number of rectangular notches in a waveguide is considered. The Fourier-transform is also employed to obtain simultaneous equations and the equations are solved to obtain an analytic solution in rapidly-convergent series. Numerical computations are performed to investigate the scattering behavior in terms of frequency and notch sizes. In Chapter 4, we design a microwave filter by using the Fourier-transform technigue. The numerical results give us various characteristics for mode converter and polarizer as well as the microwave filter. By adjustng the parameters, it is possible to design an optimum filter. In Chapter 5, we examine TE-mode surface scattering from notches in a dielectric waveguide. And we also investigate TM-mode scattering for the same structure in Chapter 6. The structure analyzed in Chapter 5 and 6 is examined for possible applications in high-gain, narrow-beamwidth leaky wave antennas.