An Investigation of Stepped Open Slot Antenna With Circular Tuning Stub

Abstract

In this article, a microstrip-fed stepped open slot antenna is presented which is suitable for GSM 1800, WiFi, WiMAX, PCS, and ITM-2000 applications. The proposed geometry is composed of a circle-shaped tuning stub, a feed structure, and deformed ground plane. The proper tuning of resonating modes (f r1 , f r2 , f r3 and f r4) and wideband frequency response are acquired by adjusting the dimension of stairs, tuning the stub and an elliptical slot. The experimental result demonstrates that this antenna covers the frequency range from 1.375 to 5.6 GHz with measured fractional bandwidth (BW (%) = 200 * (f h − f l)/(f h + f l)) of 121.14% for S 11 < −10 dB. This antenna also exhibits resonance at frequencies (measured) 1.625, 2.52, 2.82, 3.75, 4.67, and 5.42 GHz. After investigating the surface current distribution, the mathematical equations are deduced for simulated resonating frequencies of 1.35, 2, 3.8, and 5.22 GHz. Due to asymmetry in structure, asymmetric far-field patterns are found in E-plane with omnidirectional patterns in H-plane.

Microstrip Open-Slot Antenna With Wideband Dual-Frequency and Dual-Sense Circular Polarization

“…The lower frequency resonance shifts down while a resonance at the higher frequency is also excited. Ant.3 mainly improves the dislocation of the lower end of the cross slot and adopts a step structure to upgrade the coupling between the slot and feed line, resulting in a wideband response [17]. For a comprehensive comparison of the three antennas, Figure 3 shows the reflection coefficients and axis ratios obtained on the z-axis relative to the frequency changes.…”