The paper present a study of frequency shift of the reflection coefficient minimal absolute value dependence on antenna spacing in linear and circular arrays. The spacing of CB-band monopole antenna was in the range of 0.015 to 0.12 multiples of the antenna working wavelength. Number of elements in the antenna arrays ranged from two to four. Frequency dependence of minimal absolute value of the reflection coefficient was obtained by simulations and also experimentally confirmed in anechoic chamber. The research showed two facts. First, mutual impedance has the higher impact when antenna spacing is comparable with the reactive near field region. Second, circular antenna arrays are a better choice in applications for a small number of antennas with that spacing.