What does cross-polarization discrimination (XPD) indicate in radar measurements?

What does cross-polarization discrimination (XPD) indicate in radar measurements?

• A. Higher XPD indicates stronger co-polar returns and enables discrimination from cross-polar clutter.
• B. Higher XPD indicates weaker co-polar returns and makes discrimination harder.
• C. XPD measures transmitter power.
• D. XPD is only relevant for ground clutter.

Answer: (B)

Cross-polarization discrimination shows how much of the radar return stays in the original (co-polar) polarization versus leaking into the orthogonal (cross-polar) polarization. It’s typically expressed as a ratio P_co / P_cross (often in dB). A higher XPD means the co-polar component is much stronger than the cross-polar component, so cross-polar energy is weak. This makes it easier to distinguish true co-polar target returns from clutter that could appear in the cross-polar channel, because the cross-polar clutter is effectively suppressed. XPD does not measure transmitter power, and it’s not limited to ground clutter—it reflects polarization purity for any scattering scenario.

Cross-polarization discrimination shows how much of the radar return stays in the original (co-polar) polarization versus leaking into the orthogonal (cross-polar) polarization. It’s typically expressed as a ratio P_co / P_cross (often in dB). A higher XPD means the co-polar component is much stronger than the cross-polar component, so cross-polar energy is weak. This makes it easier to distinguish true co-polar target returns from clutter that could appear in the cross-polar channel, because the cross-polar clutter is effectively suppressed.

XPD does not measure transmitter power, and it’s not limited to ground clutter—it reflects polarization purity for any scattering scenario.