A Detailed Investigation of A 10 Ghz X-Band 4×7 Tapered Series-Fed Microstrip Patch Array for Radar Applications

Abstract

This paper presents a detailed design, full-wave simulation, fabrication, and experimental evaluation of a vertically polarized 4 × 7 series-fed microstrip patch antenna array intended for X-band radar operation around 10 GHz. The array contains 28 printed radiating elements arranged as four series-fed branches with seven patches per branch. The prototype is implemented on Rogers RT/duroid 5880 having a relative dielectric constant of 2.2 and a substrate thickness of 0.8 mm. A nonuniform, linearly tapered patch distribution is used in the array geometry to shape the aperture excitation and reduce the sidelobe level while preserving a simple low-profile printed structure. The antenna is modeled in Ansys HFSS and subsequently fabricated for experimental validation. The reported simulation results show a peak gain of approximately 19 dBi, a half-power beamwidth of approximately 18°, a sidelobe level about 12 dB below the main beam, and a fixed beam tilt of approximately 20°. Impedance matching is evaluated using S11 and VSWR. After fabrication, copper tuning stubs are added to the feed-divider tracks to improve the measured input match. Vector-network-analyzer measurements show a response that follows the simulated trend, while chamber measurements reported in the source indicate that the measured gain remains within approximately 0.5–1 dB of the simulated gain across the operating band. The study demonstrates the practical feasibility of a compact printed series-fed array for directional X-band radar and target-tracking applications. The paper also clarifies the relationship between element spacing, feed-line phase progression, and fixed beam tilt, and identifies measurement quantities that should be reported in future work for stronger quantitative validation.