Simple dual-slot L-shaped microstrip antenna for sub-6 GHz

This article presents the designs of simple dual-slot L-shaped microstrip antennas with coaxial-feeding that require only two cuts of slot, operating at frequencies of 0.7 GHz, 2.1 GHz, and 3.5 GHz, which align with the fifth-generation (5G) new radio (NR) frequency bands n28, n1, and n78, respectively. These antennas are designed to support low- and mid-band 5G applications while accommodating demand for simple and low-profile designs. All rectangular microstrip antennas have been designed using a fundamental microstrip formula, followed by modifications to ensure optimal performance by integrating rectangular slots on the radiating patch and variably shaped slots on the ground plane to improve the reflection coefficient, S_11, gain, and efficiency, with varying effects across frequencies. The proposed microstrip antennas yield S₁₁ less than - 10 dB, approximately 2 dB gain, and efficiency surpassing 50%. Meanwhile, the validation measurements show a minimum S₁₁ of - 18.7 dB at 0.7 GHz and a maximum gain of 2.4 dB at 3.5 GHz. All designs are simulated and analyzed in CST Microwave Studio using the Rogers RT/Duroid 5880 substrate, prior to the validation via a vector network analyzer and an anechoic chamber.