WAFER TYPE MILLIMETER WAVE RECTIFIERS 



1389 



shown in Fig. 4(b). The static characteristic of a typical unit is shown in 

 Fig. 5. 



The conversion loss of each unit is measured before the end of the 

 nickel rod carrying the contact point is cut off flush with the wafer. In 

 the event that this initial measurement shows that the conversion loss 

 exceeds an arbitrarily chosen upper limit (8.5 db), it is possible at this 

 stage to withdraw the point and replace it with a new one. This pro- 

 cedure, w^hich was necessary on only a few of the units processed, always 

 resulted in an acceptable unit. The final operation is to cut off the pro- 

 truding end of the nickel rod flush with the wafer. 



A holder designed to use the wafer units is shown in Figs. 6 and 7. At 

 the input end of the converter block is a short waveguide taper section 

 to match from standard RG98U waveguide to the ^-inch high wave- 

 guide used in the wafer unit. As the wafer unit is moved in and out to 

 match the conductance of the crystal to the waveguide, the output pin 

 of the wafer unit slides in a chuck on the inner conductor of the coaxial 



6.0 



5.5 



5.0 



4.5 



(O 4.0 

 111 

 a: 

 ai 

 Q- 3.5 



< 



J 3.0 



?2.5 



I 2.0 



cr 



^ 1.5 



1.0 



0.5 



-0.5 



•0.4 



-0.2 



0.2 



VOLTS 



0.4 



0.6 



Fig. 5 — • Static characteristic of typical millimeter-wave wafer unit. 



