June 1997, Volume 6, Number 2
In the presented submission, various moment methods for computing the current distribution and the input impedance of wire antennas are rewieved and compared. The use of various basis and weighting functions is discussed. At each method, computational requirements and accuracy are investigated.
Presented submission reviews moment methods for the analysis of cylindrical antennas. By the presented methods, which differ in the way of evaluating singular integrals appearing during the analysis, current distribution and input impedance are computed. The methods are compared from the point of view of accuracy and computational requirements. Finally, results are confronted with King-Middleton theory.
While designing microwave circuits with microstrip lines using open or shorted stubs for matching or realization of filters, the actual circuit can be substantially mismatched when the length of the open stub is below 30 degrees of electrical length, or shorted stub is over 60 degrees of electrical length. Realization of such stubs could lead to practical difficulties because the normal etching accuracy does not support the exact lengths required for such stubs.
Two novel autonomous networks containing current conveyors are presented. The design of second-order oscillators and frequency filters based on the above general networks is described. The Q-factor of the circuits designed is controllable through a grounded single resistor. Some examples illustrate the procedure described. Two new one-port elements for high-order immittance realization are shown.
A universal method for the realization of arbitrary voltage transfer function in canonic form is presented. A voltage-controlled current-source using a plus-type second-generation current conveyor is here applied as the basic building element. Filters designed according to this method have a high input impedance and low sensitivity to variations of circuit parameters. All passive elements are grounded.