A Zoom meeting screenshot of the Mixed Signals team

The Mixed Signals Team
  • Brendan Haines
  • Andrew Jeseritz
  • Kristen Kyle
  • Scott Marin
  • Rachel Williams

Watch the Demo Video  Download the Project Poster

Project Sponsor: FIRST RF Corp

A problem faced by designers of phased array radar systems is the tradeoff of granularity or beam width and system cost, size, weight and power (SWAP). By increasing the number of elements in an array, beam widths can be narrowed to improve both position accuracy of the radar, as well as signal to noise ratio (SNR) of returns. From a SWAP perspective, increasing element count is harmful since every element must have its own phase shifters, variable attenuators, and amplifiers. In particular, amplifiers negatively impact power consumption and duplicating the entire front-end rapidly increases system cost.

Another serious problem faced by radar is the issue of minuscule received power levels. Since radar requires detection of the reflection of the system’s original transmission, power levels decrease as rather than as found in communications systems. As a result, it is difficult to achieve high enough SNR to detect targets with a single pulse at long ranges. To improve SNR, the returns from multiple pulses can be integrated to effectively lower the noise floor. In traditional systems, this integration occurs after a detector. However, if samples are taken at known, constant times within a pulse repetition interval, additional gains can be achieved by integrating over time before the detector.

The FOX radar system scans an area in front of it for target detection using a phased array antenna. The advantage over existing systems is improving cost-effectiveness while maintaining excellent resolution and SNR with a pair of orthogonal linear electronically steered arrays and pre-detector integration implementation.

The FOX benefits systems that are particularly sensitive to SWAP or cost while still requiring two-dimensional beamforming. This product offers a phased array radar over a more traditional mechanically steered beam which allows for a more versatile design. The proposed system enables a higher resolution as well as a better SNR through the use of a novel array architecture in addition to pre-detector integration. The primary target use of this system is for identifying airborne objects in relatively low-risk locations. The cost and power requirements of a traditional filled phased array may be considered acceptable for small performance gains in critical locations such as military bases or other important government facilities. At lower risk locations such as small airports, sports stadiums, and schools, the high costs of filled arrays are less reasonable. This system is beneficial for human-portable installations since the array is lighter as well as require less support equipment for power and cooling.

By utilizing an orthogonal linear transmit-receive array (OLTRA), two large linear arrays can be used to make beams narrow along orthogonal axes that intersect in a small area. Cost scales only linearly with array size rather than quadratically with a typical filled array. By orienting two of these beams orthogonally, the intersection of fan-shaped beams forms a small area while only doubling cost and SWAP over a linear array, as opposed to typical radar which sees a quadratic cost and SWAP increase. The product also uses a pre-detector digital integration technique in order to improve SNR over traditional post-detector integration.