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System design and operational results of a tracking system for a K-band Earth station antenna with a diameter of 11.5 m are discussed. Monopulse tracking technique using higher order waveguide modes is utilized. An investigation was conducted to clarify the rainfall effect and the effect of oscillator phase noise on the tracking receiver.An autotrack system is to be manufactured on the basis of these studies. Experiments were performed using the medium capacity communications satellite. No cross coupling was seen in the pull-in patterns. Sufficiently good results were obtained in tracking accuracy: less than 0.0050 (peak value) under normal conditions, and less than 0.010 under an average wind velocity of more than 20 m/s.

This paper presents an interference cancellation circuit based on a side-lobe canceller. A new interference canceller is investigated in which the receiving interference signal of the auxilary antenna is modulated by a low-frequency signal. When this signal is combined with the main antenna receiving signal, envelope detection is used and the error voltage of the interference canceller will be obtained from the detection of the low-frequency signal and the phase. The interference cancellation effect is measured. The results show that above suppression ratio above 40 dB over a bandwith of 50 MHz can be achieved regardless of whether the signal is CW, FM or PSK or the undesired and desired signals are co-channel signals. For a PSK signal even with D/U = -10 dB prior to cancellation, the bit error rate after cancellation can still be maintained equal to that without interference at all. Also a good suppression ratio can even be achieved in outdoor situations and the circuit presented here has obvious practical value.

This paper presents an interference cancellation circuit based on a side-lobe canceller. A new interference canceller is investigated in which the receiving interference signal of the auxilary antenna is modulated by a low-frequency signal. When this signal is combined with the main antenna receiving signal, envelope detection is used and the error voltage of the interference canceller will be obtained from the detection of the low-frequency signal and the phase. The interference cancellation effect is measured. The results show that above suppression ratio above 40 dB over a bandwith of 50 MHz can be achieved regardless of whether the signal is CW, FM or PSK or the undesired and desired signals are co-channel signals. For a PSK signal even with D/U = -10 dB prior to cancellation, the bit error rate after cancellation can still be maintained equal to that without interference at all. Also a good suppression ratio can even be achieved in outdoor situations and the circuit presented here has obvious practical value.