Wafer-Type Millimeter Wave Rectifiers* 



By W. M. SHARPLESS 



(Manuscript received June 18, 1956) 



A wafer-type silicon point-contact rectifier and holder designed pri- 

 marily for use as the first detector in millimeter wave receivers are described. 

 Measurements made on a pilot production group of one hundred wafer 

 rectifier units yielded the following average performance data at a wave- 

 length of 5.4 millimeters: conversion loss, 7£ dh; noise ratio, 2.2; interme- 

 diate frequency output impedance 34O ohms. Methods of estimating the 

 values of the circuit parameters of a point-contact rectifier are given in an 

 Appendix. 



INTRODUCTION 



Point-contact rectifiers for millimeter waves have been in experi- 

 mental use for several years. These units, for the most part, have been 

 coaxial cartridges which were inserted in a fixed position, usually cen- 

 tered, in the waveguide. Impedance matching was accomplished by 

 means of a series of matching screws preceding the rectifier and an adjust- 

 able waveguide piston following the rectifier. Tuning screws are gener- 

 ally undesirable l^ecause of the possibility of losses, narrow band widths 

 and instability. 



It is the purpose of this paper to describe a new type millimeter-wave 

 rectifier and holder which were designed to eliminate the need for tuning 

 screws and to provide a readily interchangeable rectifier of the flat wafer 

 type. This wafer contains a short section of waveguide across which the 

 point contact rectifier is mounted. The necessary low frequency output 

 terminal (and the rectified current connection) together with the high- 

 frequency bypass capacitor, are also contained within each wafer. The 

 basic idea of the wafer-type rectifier is that the unit can be inserted in its 

 holder and moved transversely to the waveguide to obtain a resistive 

 match to the guide ; the reactive component of the rectifier impedance is 

 then tuned out by an adjustable waveguide plunger behind the rectifier. 



* This work was supported in part by Contract Nonr-687(00) with the Office 

 of Naval Research, Department of the Navy. 



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