The degree of the depolarization is often specified by the cross-polarization discrimination (XPD), which is defined by the ratio of the received co-polar signal to the received cross-polar signal. However, since XPD is defined originally for a single frequency wave, previous XPD formulas can not be directly applied to estimate depolarization effects for the case in which one channel is partially spectrum-overlapped by the other channel. In this paper, therefore, based on the assumption that the depolarization-induced interference noise generated in the overlapped spectral region in a dual-polarized satellite system is an AWGN and spreads uniformly over the whole channel, we derive a new XPD formula that would be applicable to evaluate effective XPD for the frequency-offset dual-polarized channel, as well as XPD for the completely overlapped conventional dual-polarized channel. Then, by using the proposed formula, we evaluate the BER, C/I band E{sub}b/N{sub}o resulting from the frequency offset. Simulation results of this paper indicate that the approach of frequency offset in dual-polarized systems may significantly mitigate the impact of depolarization, with a price of a somewhat extended bandwidth.
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