WaveBand, as part of a Dual Use and Science and Technology Contract in partnership with the Federal Aviation Administration and the US Air Force Research Laboratory at Rome, NY, developed a 94 GHz radar to detect birds at airports and airfields that could potentially interfere with the landing and takeoff of aircraft. The requirements for the radar system were summarized as follows:

The radar system developed by Wave-Band was subsequently given the name BIRDAR™. The radar system concept is illustrated in Figure 1. BIRDAR™ detects and reports bird activity in the airspace surrounding airports to decrease bird encounters with aircraft. The antenna scans a 30-degree by 2.5-degree or 30-degree by 5-degree field of view, depending on the model selected. Separate transmit and receive antennas are used to increase the isolation between the transmitted and received signals. A video camera is mounted on top of the radar to capture imagery from the scanned area. The primary purpose of this feature was to assist in assessing the performance of the radar during its development.

Figure 2. Simplified Birdar Transceiver Block Diagram.

The transceiver consists of transmitter and receiver sections as illustrated in Figure 2. The transmitter produces a 94 GHz signal generated by the low phase noise signal source. The signal is amplified to its final value of 575 mW. The first stage in the receiver is a low noise amplifier, which increases the backscattered signal power captured by the receive antenna and lowers the composite noise figure of the receiver. The mixer downconverts the received energy into an intermediate frequency (IF) band that extends to approximately 5 MHz. After amplification and filtering, the IF signal is passed to the data acquisition card in the PC radar signal processor. The magnitude of the voltage supplied to the motor inside the antenna module controls the speed of the spinning drums. Other power supplies provide the required voltages and currents to the transceiver components.

Figure 3. Transmitted FMCW Signal.

The radar signal processor is based on a PC architecture. The PC contains a data acquisition card that digitizes the input IF signal and converts it into a frequency-domain, Fast Fourier Transform (FFT) spectrum. The FFT represents the backscattered radar power as a function of range (measured from the radar location). There is one FFT range power spectrum for each 0.5-degree beamwidth spatial resolution angle scanned by the antenna.

The BIRDAR™ models produced for this research used an Agilent waveform generator, controlled through the PC bus to provide the linear voltage sweep that generates the FMCW signal. The magnitude of the voltage sweep adjusts the RF bandwidth of the transmitted signal to the required frequency deviation illustrated in Figure 3.

This work was done by Lawrence A. Klein and Lev Sadovnik of WaveBand Corporation for the Air Force Research Laboratory. For more information, download the Technical Support Package (free white paper) below. AFRL-0306

This Brief includes a Technical Support Package (TSP).
Development of a 94 GHz Radar System for Dedicated Bird Detection at Airports and Airfields

(reference AFRL-0306) is currently available for download from the TSP library.

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