[Microwave] testing waveguide coax transitions

[Dave Brown]

I have several w/g coax transitions (WR75, in this case)  that I want to 
test  for possible use on 10 GHz. They are ex 13GHz equipment.
As I see it, I need a well matched load on the w/g  port to sweep the 
transition, while looking into the coax port. I have to test them this way 
as I dont have anything I could use to test them looking into the w/g port. 
Question is- what should I use for the low SWR load on the w/g port?   To 
properly characterise the transition alone, a known low SWR load in WR75 (at 
10.3 GHz) is what I need.
 I have one or two w/g loads in WR75 that I could use but they are ex 13 GHz 
equipment and I dont know if they would have low SWR at 10.3 GHz.  But I 
need a transition with known characteristics at 10.3 GHz to check the w/g 
loads....This seems like a chicken and egg situation!  Similarly, a small 
horn with WR75 feed might have good enough return loss to be used as the 
load on the transition, but again, its a matter of getting a known 
transition in WR75 to check  the horn first!  Suggestions etc welcomed.
 73
 Dave, ZL3FJ