Abstract: A method is provided for adjusting the electrical characteristics and particularly the frequency of a microstrip-line printed filter with distributed constants. The method consists in depositing a strip of dielectric material on all the microstrip resonators of the filter.

Abstract: A recirculation circuit for repetition of an analog pulse signal provided with a return loop from an output divider and with an input adder for reinjecting the signal into a delay circuit connected between the adder and divider. An active circuit having a nonlinear gain characteristic is further inserted in the loop for producing a loop gain which is less than or greater than unity according as the amplitude of the signal is lower than or higher than a predetermined threshold value. So as to substantially attenuate the parasitic signals. The recirculation circuit may be further provided with a limiter circuit for delivering the repeated signal at constant amplitude.