The engineers at Narda Safety Test Solutions have successfully developed an automatic direction-finding antenna (ADFA) that delivers incomparably stable results extremely quickly. Highly insensitive to reflections, it precisely and reliably determines the direction of a detected signal. When coupled with the powerful SignalShark real-time receiver, the long list of advantages to Narda’s ADFA 1 make it into the ideal system for automatic direction-finding of signals in the frequency range from 200 MHz to 2.7 GHz. As well as for cellular network providers and the military, it is primarily aimed at PMR and BOS radio operators with applications that involve safety and security, such as the police, fire and ambulance services, frontier defense, and intelligence services.
At the heart of the ADFA 1 is an array of nine antenna elements around an omnidirectional reference antenna optimally arranged to achieve stable measurement results. The reference antenna allows test engineers to observe the spectrum at the same time as direction-finding. The principle of automatic direction-finding for a singlechannel receiver is based on the measurement of the phase difference between antenna elements. The nine antenna elements are measured against the central reference element. The greater the distance between them and the greater the recorded phase difference, the more reliable the bearings.
As well as stationary applications, the ADFA 1 can be attached to the roof of a vehicle using a magnetic mount. When connected to the SignalShark, a bearing cycle takes just 1.2 milliseconds and achieves an accuracy of up to 1° RMS (typical). Along with the simple display of the determined direction, the receiver can also overlay a so-called heat map on a stored map. The powerful localization software on the SignalShark can thus show the most likely location of the interferer directly on the screen during mobile operation. All in real time, without the need for an external computer. A hand-held antenna can be used with the SignalShark to determine the exact location of a signal source over the final few meters, so that the test engineer can enter a previously localized building in order to determine the floor and the exact room where the source is located.