Model 641

The Model 641 antenna combines vertical and horizontal signal monitoring with vertical signal DF in a compact unit. An omnidirectional biconical antenna serves as a vertical monitoring and DF reference antenna, a loop element provides horizontal monitoring, and a 9-element DF array provides direction finding on vertically polarized signals. The 641 incorporates a broadband RF switch that commutates signals from the DF elements to an external two-channel receiver and generates test signals for DF calibration and built-in self-test (BIST). Typical DF accuracy is 2 degrees (RMS)*. The 641 is available in two configurations supporting fixed and mobile/transportable applications. The mobile configuration uses an electronic flux gate compass to provide a reference for DF bearings.