Recent advances in radar imaging and sensor systems have led to demands for compact, low cost, and robust phased array front ends. For example, radars for automotive adaptive cruise control systems comprise of phased arrays which detect targets in a range of up to 150 meters, while maintaining a reasonable cost. Unfortunately, high performance phased array systems have typically been limited by the inherent complexity and bulkiness arising from additional circuitry and hardware. One of the major components which has constrained the performance of polarimetric radar systems is the antenna and its corresponding feeding system. Many of the current products are difficult to implement in a compact dual polarized array configuration, require additional hardware, or have narrow bandwidth.
Researchers at the University of Michigan have developed a compact, multibeam phased array front end device which supports independent control and characterization of vertical and horizontal polarized beams in azimuth and elevation. The device features an array of horn antennas coupled to sets of transmission lines to provide orthogonal polarizations. For separate handling of the polarizations, the device may include phase-shifting networks, which may take the form of a low loss, microstrip-based Rotman lens, coupled to the transmission lines. Focusing of radiofrequency power onto the array ports is enhanced with minimal power loss to the absorbing ports via dielectric contours of varying permittivity within the lens. The combination of a phase element coupled to the phase-shifting networks enables two polarizations to be implemented into a circular or elliptical polarization scheme. In contrast to prior efforts, the low profile tray architecture may be implemented in multiple linear array configurations without increase in antenna element spacing, while maintaining multiple capabilities demanded of modern day radar systems such as rapid beam scanning, transmit and receive functions at multiple simultaneous scan angles, and target distinction based on polarization signatures. A US patent application has been filed for this technology.
Applications and Advantages
- High resolution radar imaging
- Polarimetric radar
- Multibeam multiple-input-multiple-output systems
- Broadband point-to-multipoint communications
- Automotive collision avoidance systems
- Steerable antenna arrays
- Compact, robust, and expandable architecture
- Broadband: superior image resolution/ high data rates
- Multibeam radiofrequency beamforming
- Low cost fabrication
- High reliability, passive phase shifting network