Delivering high-performance antennas that meet the most demanding performance requirements.
RFI owns and operates an outdoor antenna test range facility in Melbourne, which is set up in accordance with the recommendations of TIA-329-C and IEEE Standard 149-1979. It is located in Tooborac, Victoria, which is a two-hour driving distance from our antenna manufacturing facility in Bayswater. The distance is far enough away from metropolitan Melbourne to ensure that RF signal levels present in the outdoor environment are low enough to not have an impact on the sensitive range measurements.
The test range is configured to operate in either ground reflection or elevated modes. Antenna pattern and gain measurements are performed using a calibrated Vector Network Analyser (VNA), calibrated Standard Gain Antennas (SGAs), a variety of source antennas, and a custom in-house developed controller application that automates the measurement and data collection process.
The Antenna Testing Facility comprises:
The source antennas and AUT are connected by solid copper-jacketed coaxial cables to the test & measurement equipment inside the shelter and are conveniently buried in conduit, allowing maintenance of the range surface and shielding them from the elements. All of the coaxial, control, and power cables enter the shelter via the grounded bulkhead panel.
The VNA executes S21 measurements between the AUT and the illuminating source antenna located at either the 50 m or 160 m source positions. The AUT is coupled to the rotator motor assembly using an appropriate fibreglass mounting fixture and is rotated through 360°, while S21 data is automatically measured and logged in 1° increments. This provides 360 data points to characterise the radiation pattern of the AUT.
Calibrated instrumentation records separate Elevation and Azimuth radiation pattern measurements. The data is acquired at seven equally spaced frequencies, five of which span the operational bandwidth of the AUT, whilst two are at frequencies just outside the lower and upper limits of the operational bandwidth.
A calibrated SGA is then placed on the fibreglass yoke assembly, rotated, and measured identically to the AUT. Since the gain of the SGA is known, the gain of the measurement setup can be calculated thereby allowing calibration of the range. Measurements are recorded at the same frequencies as those used for the pattern measurement of the AUT. The actual gain of the AUT at each of these frequencies can then be computed by referencing the measured AUT pattern data to that of the SGA, a process known as the “gain by comparison” method.
We use various source antennas and gain standards depending on the operational frequency band of the AUT. The VHF and UHF SGAs have been built following the established laboratory standard designs presented in TIA-329-C. Other SGAs include a variety of horn antennas providing contiguous coverage across 698 – 5800 MHz.
It is pertinent that the AUT is appropriately mounted to the rotator assembly so that it is firmly secured during motion and positioned precisely for the measurement at hand. A fibreglass yoke is used for the majority of base station antennas, however, smaller mobile antennas require alternative mounting structures. In the case of a ground-dependent antenna product, an appropriately sized ground plane must be fabricated and affixed to the structure and fitted with an antenna mount that provides the appropriate coaxial connections for the AUT.
We have developed and continue to maintain a custom software application that enables user-intuitive and highly repeatable control of the VNA and range hardware. This application facilitates data and metadata collection, logging, and real-time visualisation of results during pattern measurements. Furthermore, it automates the mathematical calculations for ground reflection range setup, expediting measurements and alleviating human errors during testing.
Test engineers rigorously analyse real-time data throughout the testing process, both during and immediately after test completion at the range, to maintain data integrity and accuracy. Subsequent to on-range testing, the data is further analysed at our Bayswater facility by our antenna engineering team. All collected data is meticulously stored and catalogued for future reference.
Our Tooborac antenna testing range, though geographically isolated, serves as a crucial hub for innovation and cutting-edge research. The unique environment and dedicated expertise at the range allows us to push the boundaries of antenna technology. By combining the on-site testing capabilities with the in-depth knowledge of our local engineering team, we are able to deliver high-performance antennas that meet the most demanding performance requirements.