We have written quite a bit about our High-Powered Wide Band RF sources, or Wide Band HPRF, including our test stand. Our most recent delivery to WSMR, however, really forced us to focus on a more-definitive operating performance. In the past, we simply targeted the idea of “produce as much power as possible”; whereas the WSMR customer wanted more consistency across the operating spectrum. Our target specification became 234 V/m/MHz, when measured at 5 m.
Meeting a Higher Standard of Consistency
Generally, we have pitched the idea that a single Wide Band RF source can employ multiple antennas, with each antenna tuned to operate at a specific center frequency. We then design and build antennas to fill specific region of the frequency spectrum, working to see overlapping the 3 dB points on neighboring antennas. Our new target specification was to maintain 234 V/m/MHz (at 5 m) across the desired spectrum, 150 MHz through 400 MHz.
The Multi-Antenna Approach
The delivered system is shown below and includes additional measurement equipment that was not part of the delivery. The system that was delivered included the test stand (shown with a mounted antenna), three additional antennas and the power & control console.
The customer’s specific requirement was for a system delivering more than 234 V/m/MHz at a 5 m range and across the 150 – 400 MHz range. The system we provided did that, using four unique antennas, as shown in the figure below.
An easier to understand representation is shown below and simply graphed as the electric field strength, E (kV/m).
We accomplished this pattern by uniquely designing the four antennas, each with a near-specific center frequency and relying on their wide band performance to overlap in the frequency domain. This concept worked out well. For completeness, we include the radiated waveforms from each antenna.
This system reflects APELC’s evolving approach to wide band RF testing, prioritizing spectrum consistency and customer-specific precision. Future work will continue to refine repeatability across even broader bandwidths.
If you’re interested in how this multi-antenna design can scale to your testing environment, reach out to us here.
