Circularly Polarized X-Band Microstrip Antenna with 2x2 CSRR Grid for IoT Applications in Dynamic and Interfered Environments

The increasing demand for IoT services is driving a trend toward the migration of applications to higher frequency bands, aiming for higher data rates. This paper presents a microstrip antenna with circular polarization, designed for the X-band (8-12 GHz), featuring reduced dimensions and a 2x2 array configuration of square patches with truncated corners. The antenna incorporates CSRR-type metamaterials in each patch and uses parasitic elements in the feed network to optimize performance. Circular polarization was verified, and the antenna exhibited dual-band behavior with a lower band in the range of 10.0–10.45 GHz and an upper band of greater interest in the range of 10.87–11.53 GHz, achieving a 10 dB bandwidth of 660 MHz and ARBW (axial ratio bandwidth) of 240 MHz. These characteristics make the proposed antenna suitable for low-power IoT systems, such as remote monitoring sensors, offering stable performance even in dynamic environments with high interference.