Elevation finding algorithm in beam domain under multi-path environments for VHF radar

A novel elevation finding algorithm in the beam domain is proposed for very high frequency (VHF) radar under multi-path environments. Three orthogonal beams (upper, middle and lower beams) are formed using fast Fourier transform. The orthogonal vector of the covariance matrix in beam domain is analytically derived to form the angle spectrum, the peak of which corresponds to the estimation of the elevation of the target. In addition, the complex reflection coefficient (CRC) is also available when the elevation is estimated. The validity and veracity of the proposed scheme is verified with simulations. The relationships between the estimation performance, the signal-to-noise-ratio, elevation and CRC are also investigated, respectively. Furthermore, field data sets are used for validation. It is found that when the elevation is <;1/5 of the beamwidth, which poses great difficulty for elevation estimation. The estimation precision is still <;1/35 of the beamwidth. The proposed algorithm is particularly suitable for VHF band radars and ship-borne radars, where the multi-path effect is serious.