Need help with Coaxial Probe Feed into a Rectangular Cavity

Hi everyone,

I'm simulating a rectangular microwave cavity using a coaxial probe feed.

The Problem: When I run the Eigenmode Solver I clearly see Mode 1 at 2.518 GHz. However, when I switch to the Time Domain Solver to get S-Parameters, my S11 graph shows that no energy is being coupled into the cavity.

S11 Graph

My Setup:

Cavity: I first defined a solid Aluminum brick then performed a Boolean Subtract using a vacuum block to create the internal resonant cavity.

Feed: Coaxial probe (Standing alone, the coaxial probe simulation works perfectly)

Background: Set to Normal

Boundaries: All set to Et = 0

Internal cross-section of the setup

What I've Checked:

1. I've ensured the center pin is NOT touching the aluminum walls

2. The probe depth is about 25 mm inside the cavity

Question: Why is the energy not coupling into the mode found by the Eigenmode solver?

Thanks in advance !