| 摘要 |
Embodiments of the invention are concerned with frequency scanning antennas for transceiving radio frequency energy for use in detecting and monitoring ground-based targets. In one arrangement the frequency scanning antenna is embodied as a structure that is capable of emitting a radio frequency beam to a plurality of different angles about the antenna structure: the antenna structure comprises at least two travelling wave antennas, and the travelling wave antennas are disposed within the antenna structure such that the antenna structure is capable of emitting the beam at a first angle using one of said two travelling wave antennas and of emitting the beam at a second angle, different to said first angle, using the other of said two travelling wave antennas. |
