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Researchers have studied the behavior of the vector channel in order to study the quality of beamforming methods and to increase downlink signal power and signal-to-interference ratio. Jeng (see IEEE Trans. Antennas Propagat., vol.46, p.749-57, 1998) showed that knowledge beyond simply directions of arrival of the vector channel at one frequency may not be useful at another. We propose that if the ratio between two frequencies, f1 and f2, is close to one, then the autoregressive (AR) coefficients which model the behavior of the vector channel at f1 are essentially the same AR coefficients as those which model the vector channel at f2. This implies that accurate predictions of the vector channel at f2 can be performed knowing only the channel at f1, as well as enough knowledge of the channel at f2 in order to provide initial conditions. Ray-tracing simulations of downtown Austin, TX, show that this hypothesis holds for f1 = 1.85 GHz and f2 = 1.93 GHz, which correspond to uplink and downlink frequencies, respectively, in US personal communications systems.