VARIABLE ATTENUATOR FOR MICROSTRIP
Original Publication Date: 1983-Mar-01
Included in the Prior Art Database: 2001-Oct-08
Variable attenuators for microstrip are often implemented by placing a vane of resistive material mounted on a pivot above a section of the line. The attenuation is adjusted by rotating the vane and thus varying the amount of line covered. Although this design is simple, it does have several 5 drawbacks. First of all, appreciable area is needed on the circuit board. Secondly, and more significant- ly, the impedance seen by both the input and the output is usually a large mismatch relative to that of the microstrip line. Most attenuation is due to this mismatch which makes this device often unusable in sensitive circuits.