Sidelobe Canceller (SLC) System Theory And Its Implementation

This article describes a Side Lobe Canceller (SLC) Array with ISdB.the approach is to design 3 auxiliary antennas and to load them around the main antenna ?AF radar. Then the canceling ability of this system will be analyzed when it receives various interference. We will also talk about in detail how this system will perform when existing some practical affecters such as interfering signal bandwidth, channel consistence, polarization, gain differences between main antenna and auxiliary antennas, additional with computed results and figures.In order to avoiding complexity resulting from number of changes, we do the follows: at first, we assume that in perfect situation, the interfering signal arrival angles all known, put the 3 auxiliary antennas on the beginning positions. Then in terms of the principle of CR maximum, we move one of the auxiliary antennas within certain angular range, adjusting it slightly many times. At last, together with the effect of working frequency, the optimum position of the auxiliary antennas will be given.In practice, when existing interfering signal bandwidth, with increasing of the number of interference, the wider the bandwidth is, the more rapidly the CR will decrease. Only when interfering signal bandwidth is not zero, can the effect of propagating delaying and differences between channels be apparent, that's to say the bandwidth is the dominate affecter.In order to simplify the problem of multi-path, we decompose the interfering signals on the horizontal plane and vertical plane. The reason that excess degrees of freedom causes bad CR when this system receives 3 interferences.From analysis, we can see that the system perform best when main antenna has pattern with low SLL and the auxiliary antennas have patterns similar with the SLL of the main antenna at the interfering signal arrival angles. If we can make the gain differences less than 3dB,the decreasingamount of CR will be less than 5dB.It also shown that it's much more important to make the main antenna polarization coincident with the auxiliary antennas polarization than to receive interferences whose polarization is different from antenna polarization.