Distortionless Spatial Frequency Adaptive Processing in Antenna Array GNSS Receivers

Spatial frequency adaptive processing (SFAP) is the suboptimal form of spatial temporal adaptive processing (STAP). It is an effective measure of mitigating radio interferences in global navigation satellite system (GNSS) receivers, and is less computationally costly because of dimensionality reduction. Just as STAP, if no additional countermeasures are adopted, distortion will be induced to the desired navigation satellite signals due to the non-ideal factors of the array antenna and the radio frequency (RF) channels, resulting in the measurements and the final position to be biased in the receiver. In this paper, a distortionless beam-forming method is proposed, which forces the steering vectors to be matched with the frequency responses of the antenna elements and RF channels in finite frequency sample points. A simulated array antenna with high fidelity is used to validate this method. Results shows that the measurement biases can be avoided as long as proper overlap is performed between the data blocks in SFAP.