A low Q-factor compact wideband microstrip patch antenna with stabilized gain for 5G and IoT applications

This paper presents the design and optimization of a compact wideband microstrip patch antenna, created through an evolutionary approach for future wireless communication systems. The antenna design goes through six stages, starting from a standard rectangular patch and adding circular stubs, semicircular and L shaped slots, meandered line and a defected ground structure. Each change is made to improve resonant behavior, surface current distribution and impedance bandwidth. The optimized antenna operates at 3.58 GHz and 5.3 GHz. It has a wide impedance bandwidth of 2.6 GHz (FBW ≈ 57.8%), high radiation efficiency of 78% and a low Q-factor of 1.73, indicating a strong wideband behavior (estimated using fractional bandwidth). The proposed antenna exhibits minimal gain variation across the operating band, with values between 2.9 dBi and 3.0 dBi, while maintaining consistent radiation and impedance characteristics. Electric field and surface current analyses show that controlled phase distribution and a small group delay variation (0.3 ns to 0.5 ns), which supports near-linear phase characteristics. The proposed antenna combines wide bandwidth, low group delay, minimal gain variation, high efficiency, low Q-factor and compact size, making it suitable for 5G sub-6 GHz, internet of things and wearable devices.