Dielectric GRIN Luneburg Lens for Enhanced Radar Sensing in Communication Systems

This article presents a design methodology to enhance the radiation efficiency of compact modular radar systems by employing an advanced spherical dielectric gradient-index (GRIN) Luneburg lens with tunable refractive index gradients. The proposed design utilizes computationally optimized dual-beam masks, implemented as two exponentially tapered rods, to modify the conventional permittivity distribution of the Luneburg lens. This approach enables the use of a single lens for both transmitter (TX) and receiver (RX) radar microstrip antennas while addressing beam tilting issues. To validate the design, a prototype of the GRIN modified Luneburg lens (MLL) was manufactured using a cost-effective and uniform 3-D-printing technique and seamlessly integrated with a commercially available X-band radar module. The experimental evaluation was conducted in a laboratory setting, measuring transmitted power using a standard X-band horn antenna connected to a spectrum analyzer and strategically positioned within the radar’s radiation field at various aperture-to-aperture distances. Received power measurements were also recorded at the radar RX antenna, demonstrating significant improvements in both transmitted and received power. These enhancements collectively contribute to a substantial increase in the radar’s signal-to-noise ratio (SNR) for high-gain communication systems. The MLL-enhanced radar module achieves a realized gain of 17.2 dB at 10.4 GHz, resulting in a 3.2-fold extension of the radar’s detection range in both elevation and azimuth directions. Additionally, the integration of the GRIN MLL leads to a 10-dB enhancement in received power, corresponding to a tenfold improvement in SNR when operating along the boresight. These findings validate the effectiveness and robustness of the proposed design in radar sensing enhancement.