| 摘要 |
A low profile, dual purpose antenna (1) for simultaneous UHF and LF use has two coplanar antenna elements (7,8), one of which is circular (7) and the other of which is a concentric annulus (8) separated from it by a dielectric, as well as a third, linear antenna element (10) extending from the centre of the circular element (7). The circular element (8) serves both to assist in tuning the UHF section of the antenna and as a voltage probe for the electrostatic component of the LF signal. Integrated (9) within the antenna housing (2) is a high input impedance, low noise amplifier for bandwidth limiting the LF signals. A coaxial feeder cable (11) serves to connect both UHF and LF sections of the antenna to external equipment. Entry for the coaxial feeder cable into the antenna housing is through a threaded collar (30), which also acts as a single point fixing of the antenna to the roof of a vehicle. <IMAGE> |
