Overview

From APPLIED MICROWAVE & WIRELESS, VOL. 10, NO. 9, NOVEMBER/DECEMBER 1998

Physical transmission lines have frequency dependent attenuation that increases its loss as the operating frequency increases. This phenomenon can pose severe problems in broadband systems and should be compensated for to obtain a flat attenuation response with frequency. The gain equalizer is a passive component that flattens linear increase in attenuation (or decrease in gain) that may be exhibited by a component or subsystem. Cable loss equalizers may be used in certain EW systems as CATV amplitude equalizers or amplifier gain equalizers and in other applications with frequency-dependent loss.

This article discusses a topology for such an equalizer as well as the development of an equalizer that flattens a 11 dB attenuation slope of a coaxial cable in the 6 to 18 GHz frequency range. The circuit was developed for microstrip construction, using the linear simulation package Touchstone .

Coaxial Cable Characteristics

Coaxial cable offers a dispersionless medium for the propagation of electromagnetic energy in the TEM-mode. Cable attenuation depends on physical characteristics of cable and length. The insertion loss of the coaxial transmission line comprises conductor loss ( ? _c) and dielectric loss ( ? _d), given by:

where L is the length of the cable and ? _c, ? _d are given by:

and

where

• d ₁ is the diameter of the...