STI Undetectability - Why?
What makes the STI so undetectable/different from other RDs (such as the V1)?
I recall it being a combination of the way the case is shielded and also the design and placement of the receiver horns.
The #1 thing that makes the STI undetectable is the use of LNA's (Low Noise Amplifiers) in the front end. These provide high reverse isolation, letting signals in, but keeping signals from leaking out.
What little leakage the LNA's don't take care of is eliminated through the use of waveguide and microstrip filtering.
The V1 was the first detector to use LNA's in the front end, and prior to the STI's release, the V1 performed the best against Spectre. But the V1 only uses one for X-Band, while the STi uses LNA's on all bands.
One other difference is that the STi uses separate antennas and mixers for X-Band and K/Ka band. This might allow them to filter more efficiently, while perhaps also helping them to get around another company's patent regarding the use of LNA's in a detector with a single mixer.