emv and NSI (Nearfield Systems Inc.) refurbish an obsolescent Far-field antenna measurement system at Ramet in the Czech Republic and thereby integrate state-of-the-art measurement instrumentation and the NSI 2000 software with the existing positioner.

The Starting Situation
Near-field and Far-field antenna measurement systems are employed for the characterization of antennas. Antenna and radar manufacturers demand high standards for the quality and precision
of the measurement technology. Older antenna
measurement systems are often unable to give the
required measurement precision or to deliver detailed measurement protocols. Despite great own
maintenance efforts, this was becoming the case at
the Czech radar equipment and antenna producer
Ramet C.H.M. A 35 year old Far-field measurement
system from Scientific Atlanta could not satisfy modern demands. Manual generation of measurement protocols, a high breakdown risk and unobtainable spare parts were some of the reasons for the decision to completely replace the measurement instrumentation and control of the system.

The Task
The customer wanted to fully modernize the antenna measurement system with new RF measurement instrumentation while economizing by continuing to use the existing mechanical equipment. The existing RF measurement equipment should be completely replaced. The measurement equipment had to be installed 25 meters above the ground in two measurement towers. The measurement distance between the towers was 1024 meters. The existing AUT positioner with 5 ton load capacity needed a complete overhaul, including replacement of the motor for each of the 3 rotation axes, new cabling, and replacement of the existing connections.

The Solution
After inspection of the old measurement installation and detailed analysis emv and NSI proposed a concept retaining the original positioner. emv with NSI was the only vendor able to satisfy the strict technical requirements with a really attractive and economical solution. This was made possible by including the customer in the overhauling of the positioner. The skills of the customer made it possible for various jobs to be taken over by Ramet, for instance replacement of the existing connections after precise definition of the interfaces. The delivery comprised a complete RF subsystem up to 20 GHz with the corresponding NSI software, a network analyzer (PNA from Agilent), a signal generator and a control unit from the French manufacturer ACC.