A Low-Cost Ku-Band Planar Frequency-Phase Scanning Array Antenna for Low-Altitude Target Detection Applications

Abstract

This letter proposes a hybrid scanning regime phased array antenna that combines frequency and phase scanning to achieve multi-target detection and tracking in the 360° azimuthal (AZ) direction through mechanical and phase scanning, as well as elevation (EL) target detection by frequency scanning. The microstrip slow-wave line serves as a feed to the radiating patch, enabling frequency scanning. The strip line is coupled with energy through slots of different sizes, exciting the patch antennas, which can effectively enhance the impedance bandwidth of the line array. The Genetic Algorithm (GA) is used to design a low side lobe level (SLL) frequency-scanning line array, and metallic through-vias are utilized to reduce mutual coupling between line arrays, ensuring good active standing-wave radio (AVSWR) performance after two-dimensional phased array formation. The proposed frequency-phase scanning array antenna was fabricated and tested. The array consists of 48 series-fed line arrays arranged in the azimuth direction, all integrated onto a single PCB board measuring approximately 175 × 432 × 1.016 mm³ (9.7 × 24.2 × 0.06 λ³). This design offers advantages of low-profile, light-weight, and high-integration. And it can achieve ±45° phase scanning in the azimuth direction within a bandwidth of 15.7–17.7 GHz (12%), with SLL better than −26.1 dB. Additionally, it provides frequency scanning range greater than 21.4° and SLL better than −16.1 dB. The aperture efficiency ranges from 70% to 85%, and the maximum gain of the array reaches 35.9 dBi.