Radar Field Analyser - RFA641 Edition Date: 28-Feb-18
3. UPLINK
3.1. Theory
The Uplink measurement will provide you with horizontal polar diagrams of any (M)SSR/PSR antenna in its
operational environment by recording the pulses of the radar. For this purpose the Radar Field Analyser is
set-up in the field with no connection to the radar. An antenna will pick up the radar signal from the air (P1-
P2-P3 1030MHz or PSR transmissions) and the Uplink software calculates the HPD antenna diagram from
this data.
The pulses can be recorded in a condensed format (pulse mode) or in detail (scope mode). After the
recording the HPD can be extracted from the data through fingerprinting (stagger).
When selecting a measurement position for the RFA641 setup, take into account the following guidelines:
• Make sure to have direct line of sight to the radar under test and place the RFA641 at a distance of
min. 0.5km and max. 40km.
• Place the antenna at least 1.5m above ground level, preferably even higher. If the radar station
remains visible, even when standing behind the antenna, a good measurement result may be
expected.
• Choose the correct antenna polarization. All SSRs are vertically polarized. Primary radars can be
vertical (most common), horizontal or circular.
• It is advisable to record the antenna signals in both polarization modes. That way, whatever the
mode used, or expected, the data is never lost. At the same time the cross polarization is measured,
including the effect of the environment. Usually the effect of a high cross polarization is caused by
reflections. Therefore it can be used to determine bad positioning of the measuring antenna for
reference measurements.
• Beware of nearby buildings or other structures reflecting large portions of the signal. These
reflections may influence your measurement.
• The most frequent error is a measurement from a too low elevation angle. The HPD diagram is still
correct but doesn’t represent the view of the targets and antenna. If in doubt, use an inclinometer to
find the elevation angle from the measurement position towards the radar under test.
• Depending on the distance of the RFA641 Uplink setup to the radar system, extra attenuation must
be inserted at the Rx input of the RFA641. As a general rule it is best to start with 20dB (SSR) or
40dB attenuation (PSR) between the antenna cable and the YIG input.
3.2. Getting Started
The Uplink is loaded from the RASS-S Toolbox using the Uplink button.
Make the connections as shown in Annex 2: Uplink Connection Diagram.
IE-UM-00165-005 RFA641 User Manual.odt 21/110
To Next Page
Loading...