To: File

From: Jon Hagen

Date: 10-6-99

Subject: Half-height WR2100-to-coax Transition

The 430 radar system in the Gregorian dome will require a	half-height waveguide-to-coax transition at the turnstile for the receiver connection. For radar astronomy operation, two transitions will be needed. These transitions should be as short as possible. The design shown in the figure below was made with the aid of the Ansoft 3-d electromagnetic simulator program, HFSS. It consists of an electric probe, slightly off center, and an inductive tuning post.

The predicted performance is as follows:

420 MHz: S11 = -39.3 dB

430 MHz: S11 = -29.8 dB

440 MHz: S11 = -23.7 dB