Abstract: A device for testing the accuracy of an attenuator, over a range of frequencies from 1 to 18 GHz, for example, and having a first variable frequency signal generator which passes its output through the attenuator. The resulting output signal, and a local oscillator/mixer combination produce an IF signal (Hereinafter, "first signal"). A second signal source, at the IF frequency, passes its output through a variable attenuator and a step attenuator to produce a "second signal". The "first" and "second" signals are fed to a closed loop which includes an integrator that controls the variable attenuator to tend to keep the first and second signals at the same amplitude. A branch circuit, controls a second step attenuator; and includes means to produce an output level the value of which represents the value of signal level of the "first signal". The bandwidth of the closed loop is automatically narrowed when the amplitude of said first signal is low to give an optimum signal to noise ratio, under all conditions.

Abstract: A coaxial transmission line for u.h.f. waves, and particularly for use with slotted line equipment, in which the center conductor is supported coaxially within the outer conductor by spaced dielectric pins extending radially between said conductors, wherein wave reflections are minimized by means of counter-bored areas in the form of shallow depressions in the surface of the inner conductor where it is engaged by said pins, said depressions completely surrounding the point of engagement of each pin with said inner conductor and being dimensioned to produce an inductive effect to compensate for the capacitive effect of the dielectric pins.