In looking at the reflections from our 4 port ENA (correction turned off), we noticed an extra internal reflection on ports 2 and 3. Note that the ports are all open (nothing connected). S11 and S44 look as expected - a single reflection from the open port. However, ports 2 and 3 have an extra reflection occurring before the open port (evident in the time domain). All the cross port terms look as expected.
Reflection parameters are attached in both frequency and time domain. I'm wondering if the ENA is need of repair?