Four Port Square Shaped Spiral MIMO Antenna at Multiple Frequencies in C Band & X Band

Next-generation wireless communication systems increasingly rely on Multiple Input Multiple Output (MIMO) techniques to achieve high data transmission rates. This paper presents a four-port spiral MIMO antenna, designed to operate across multiple frequencies in the C and X bands for wireless communication. The antenna system, which features four radiating elements on a cost-effective FR4 substrate with a thickness of 1.5 mm, operates at frequencies of 5.3 GHz, 5.8 GHz, 6.9 GHz, 7.4 GHz, 10.9 GHz, and 11.6 GHz. The design and simulations were performed using CST software. The proposed antenna has dimensions of 28 mm x 28 mm x 1.5 mm and demonstrates strong performance with isolation below -15 dB, Envelope Correlation Coefficient (ECC) under 0.01, nearly 10 dB Diversity Gain (DG), and a gain exceeding 5.5 dB across all specified frequencies. Performance of this antenna is compared with that of similar types of antennas found in recently published papers.