Radar Field Analyser - RFA641 Edition Date: 28-Feb-18
1. TECHNICAL MANUAL RFA641
1.1. General Introduction
The RFA641 is intended for on-site performance checks of (M)SSR ATC radars and primary radars in L and
S band. For this purpose, the radar does not have to be taken out of its operational mode. The transmission
pattern (power) of the LVA or horn-feed antennas is continuously measured and plotted versus azimuth or
time. All antenna measurements are intended to be performed during a regular check-up or maintenance of
the radar, often because the antenna is damaged or degraded due to the harsh environment.
Additionally to its primary usage as antenna evaluation tool, the RFA641 can also perform the following tests:
• Uplink (Transmission) antenna diagram: Pulse power = f(Azimuth);
• Generation of test pulses for Downlink (Reception) Antenna Diagram: Rx Pulse power = f(Azimuth);
• Receiver sensitivity sweeps: Receiver Output Voltage = f(Power);
• Receiver bandwidth sweeps: Pow = f(Freq.) and spurious responses;
• STC sweeps: Power = f(delay after trigger);
• Sectorial STC: Power = f(delay after trigger, Azimuth);
• DSTC and sectorial DSTC: same as above for Quantised Video Receivers;
• Transmitter power, spectrum, pulse shape recording, timing, mode and stagger verification;
• FRUIT generation for environment simulation;
• Mode-S interrogation generator for transponder verification;
• Transponder quality verification;
• Target injection for non-pulse-compression primary radars.
The Uplink (Tx) antenna diagram can be measured by using the frequency-controlled receiver input on the
RFA641. Using VCO's and filtering techniques, a frequency range from 900 MHz up to 3.0 or 3.5GHz
(optional) is covered both in the reception and transmission path. This allows the use of the same instrument
on a wide variety of radars. The antenna diagram can be extracted for different radars at any time (e.g.
multiple SSRs on one site) by means of the analysis software.
The Downlink (Rx) antenna diagram can be measured with the Radar Interface Module (RIM782) connected
to the receiver of the radar and the RFA641 set-up in the field, producing test pulses at a selected frequency.
This recording is slaved to the antenna rotation.
1.2. Key Features
• With its measurement frequency tuneable in the 900...3000MHz frequency range, the RFA641
supports both (M)SSR and PSR systems.
• RF receiver for reception of RF interrogations with the purpose to measure the antenna diagram in
transmission (uplink).
• RF Tx module for generation of test pulses for reception (downlink) pattern measurements and for
receiver measurements (alignment, sensitivity, bandwidth, STC...).
• Data acquisition engine with DSP processing and USB2 interface for direct spooling of the captured
pulse data to disk for later analysis. This enables a ‘one button’ semi-automated measurement
approach.
• Simple and easy set-up: connect the Radar Field Analyser to the measurement antenna, start up the
host computer, take power from a car battery or a UPS and start measuring.
• Highly portable and easily carried by one person.
• Frequency extension available as option.
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