HF null steering system with a wide-band structure

摘要

Antenna array adaptive null-steering, which is a relatively new concept in HF offers the possibility of suppressing undesirable interferences, while preserving the desired signal. But good performance requires both special structures and high quality electronic circuits, especially for attenuators and phase shifters. It also requires a good mastering of parasitic delays and of impedance matching throughout the system. The wideband structure presented overcomes most of the limitations exhibited by classical systems. It has proved to have 0.1 dB attenuation and 0.2 degrees phase shift resolution, along with high stability. This results in -50 dB average cancellation ratio, and 1.8 MHz cancellation bandwidth at -40 dB cancellation level, resulting in a 20 dB improvement over narrowband systems.