Senji Yokokawa

Design for a variable phase shifter using lines and variable capacitance diodes

We present a design of a variable phase shifter, composed of transmission lines and variable capacitance diodes. This variable phase shifter has a simple structure and a small physical size. It is designed so as to keep its attenuation within the allowable range even though the capacities of the variable capacitance diodes are varied. The experimental results of a trial variable phase shifter agree with the theory.

An approximate method of step response for binomial transmission line to step wave

We show equations to obtain the initial arriving voltage at the output end in an arbitrary lossless nonuniform transmission line (NTL), and present a simple method to approximate a step response at the output end of a binomial transmission line (BTL) to a step wave using these equations. That even in BTLs with different intrinsic impedance distribution, the time response at each output end may become identical, is shown by a design example. It is further shown that NTLs with same time response but with different structures are in the relationship of inverse circuits with each other.

A new recursion formula at the ends of nonuniform coupled transmission lines for FDTD analysis

A method of applying the FDTD method to the nonuniform coupled transmission lines is described. The advantage of this method is that the accuracy of the numerical analysis is high when the propagation velocities of each mode are different. The mode decomposition is used only at both ends of the transmission lines. As a numerical example, the step response of the parabolic coupled transmission lines in an inhomogeneous medium where the mode velocities are not identical is presented.

A two-way power divider using coupled lines and capacitances

This paper describes the design of a compact two-way power divider composed of coupled lines and capacitances instead of a quarter-wavelength transmission line. The coupled lines are made compact by an approach in which the line lengths of even and odd mode circuits of the coupled lines are shortened by capacitances. Also, the compact coupled lines have an image impedance independent of frequency, as in the case of transmission lines. Tests of a trial power divider show that this design is effective. In addition, it is shown that a broadband power divider cascaded from two such coupled line sections can be designed.