A new 449 MHz wind profiler radar: evaluation of antennas, amplifiers and capabilities

The National Center for Atmospheric Research (NCAR) deploys 915 MHz wind profilers, primarily for probing the boundary layer and precipitation studies. We aim to extend our profiling range and capability using a new 449 MHz modular design that also provides more flexible deployment options. In the past, 449 MHz antennas were too large for rapid deployment. New compact, modular antennas and high efficiency RF amplifier designs present the opportunity to develop scalable wind profilers at 449 MHz. Multiple modules would be clustered together to probe deep into the troposphere; alternatively fewer modules would be deployed when the primary interest is just the boundary layer. A circular patch array antenna has been designed and tested with sidelobes measured at least 35 dB lower than the main beam. Aside from adding more antenna modules to increase the effective aperture, we have explored other system improvements. We have been testing various power amplifiers including single transistor Class-E amplifiers with power efficiency up to 80%. Phase matching of cables and power splitters is important for a uniform antenna pattern. Circulators are a critical component because of the need to detect low level winds down to 150 meters. These technologies will improve the portability and signal to noise ratio of the system, to provide an easily deployable high sensitivity radar wind profiler suitable for land or ship-based operations.