Direcway HughesNet TRIA overview..

Greg, I found this text..

TrIA Overview

The Transmit Receive Isolation Assembly (TRIA) consists of the following functional components: an orthomode transducer (OMT), a high-pass filter in the TX path, and a bandpass filter in each of the RX paths.  The TRIA connects to the transmitter, LNB and antenna feedhorn.  It allows the VSAT terminal to transmit and receive at the same time while conforming to the overall spurious mask requirements of the various satellite authorities.  

Two different trias are used with the ISIS radio assembly.  One tria is used with the ISIS-Pure radio assembly and a different tria is used with the ISIS-TG radio assembly.  The main difference between the two trias is that the one used with the ISIS-Pure radio is capable of receiving both receive polarizations while the one used with the ISIS-TG radio can only receive the polarization orthogonal to the transmit signal.

ISIS-Pure Ku-band TRIA Ports
The various ports for the TRIA used with the ISIS-Pure radio.  The common port receives Vertical Polarized (V-P) and Horizontal Polarized (H-P) electromagnetic energy in the Receive (RX) band while transmitting either V-P or H-P.  The transmit polarization is set during installation to V-P or H-P by rotating the TRIA unit 0 degrees or 90 degrees relative to the antenna feedhorn.  The TRIA provides transmit rejection, receive band spurious, and receive band noise rejection at the receive ports.  Further, the TRIA provides isolation between RX ports.  The common port supports a .645” square waveguide, the RX ports support custom dual .375” x .750” waveguides, and the Transmit (TX) port supports a standard WR75 waveguide.  

The frequency of operation for the common port is 10.95-14.50 GHz.  The interface is a square waveguide.
The frequency of operation of the TX port is 13.75 GHz–14.50 GHz.  The interface is a standard WR75 waveguide.
The frequency of operation for the RX orthogonal port is 10.95 GHz–12.75 GHz and 11.7–12.2 GHz for the RX co-linear port.  

ISIS-TG Ku-band TRIA Ports
The ports for the TRIA used with the ISIS-TG radio.  The common port receives Vertical Polarized (V-P) and Horizontal Polarized (H-P) electromagnetic energy in the Receive (RX) band while transmitting either V-P or H-P.  The transmit polarization is set during installation to by rotating the entire ISIS-TG radio 0  ±110 degrees in the mounting cradle that attaches to the antenna.  The TRIA provides transmit rejection, receive band spurious, and receive band noise rejection at the receive port.  The common port supports a .645” square waveguide, the RX port supports a custom .375” x .750” waveguide, and the Transmit (TX) port supports a standard WR75 waveguide.  

The frequency of operation for the common port is 10.95-14.50 GHz.  The interface is a square waveguide.
The frequency of operation of the TX port is 13.75 GHz–14.50 GHz.  The interface is a standard WR75 waveguide.
The frequency of operation for the RX orthogonal port is 10.95 GHz–12.75 GHz.

In the Pure section above I emphasis the word transmitting in italics.  Note that the aternative transmit polarisations are achieved by turning the entire unit 90 deg - so it is a single polarisation transmit system.