Been analyzing signal degradation on my 70cm EME setup and trying to understand the relative impact of libration fading versus Faraday rotation. Faraday rotation and libration fading come into play during EME contacts, with full 360 degree rotation possible at 432 MHz. The libration fading is due to multiple wavefronts being received from different parts of the moon summing up, changing with relative movements of earth and moon.

Running dual-pol circular arrays (4x28el) but still seeing 10-15dB signal swings that seem too large for just libration. Polarization rotation effect is more pronounced at lower VHF frequencies and becomes less significant at 1296 MHz and above. Anyone have experience quantifying these effects separately?

Setup: IC-9700, 500W SSPA, 0.4dB NF preamp, EME144 software for tracking.

At 70cm you're seeing both effects but Faraday rotation is more pronounced at lower VHF frequencies. Your 10-15dB swings sound typical - libration gives you the faster QSB while Faraday causes the slower polarization changes. Try logging signal strength vs moon elevation to separate the two effects.

Libration fading is caused by the libration movement, with the receiver experiencing fading distributed about a median value. On 70cm I've measured libration fading typically 3-6dB peak-to-peak. Your larger swings suggest Faraday rotation is dominant. Consider switching to linear horizontal polarization for testing.

I've found that MAP65 with coherent signal channels for two orthogonal polarizations can yield automatic polarization-matched reception really helps on 70cm. Some polarization mismatch loss can be reduced by using a larger antenna array. Your 4x28el should have enough aperture to minimize both effects compared to smaller arrays.