Research On Miniaturization Of S-band Antenn

The frequency range of S-band is 2～4GHz,Sub-6 band as the new radio band for5 G mobile communication,of which N77 and N78 bands are within the S-band,the daily used Bluetooth communication,Wi Fi and radar are working in this band.With the rapid development of 5G application technology,microwave and ultra-large-scale integrated circuit technology has also been rapidly developed,which also requires the development of communication electronic equipment towards miniaturization and intelligence.This puts forward higher requirements for the miniaturization design of antennas.In this paper,two miniaturized microstrip antennas operating in S-band are designed by using folding technology and composite left-and right-handed transmission line theory.The main studies are as follows:1.For the miniaturized microstrip antenna using the folding technology,a small circularly polarized microstrip antenna is designed and simulated,which achieves circularly polarized radiation by loading an inclined fractal slot on the grounding plate and using a coaxial probe for power feeding.The miniaturized design is specifically embodied in the radiation patch of the antenna loaded with U-shaped slot,which makes the current on the surface of the patch flow around the U-shaped slot zigzag,effectively increasing the electrical length of the antenna and reducing its resonant frequency.According to the analysis of the antenna current diagram,it can be proved that the antenna current after slotting is mainly concentrated near the U-shaped slot and in the opposite direction,which can affect the resonant mode of the antenna.Test results show that the antenna return loss value below-10 d B effective frequency range is 2.13GHz-2.28 GHz,relative bandwidth is 6.9%,maximum gain value is 0d B.compared with the same size of ordinary microstrip antenna,its center frequency is decreased by 0.55 GHz.2.A miniaturized shared aperture dual-polarized omnidirectional antenna,utilizing the composite left-and right-handed transmission line theory,is designed and tested.To achieve its broadband and compact characteristics,the vertically polarized and horizontally polarized waves share a common physical area and are fed by using coaxial probe and side-fed networks.Symmetrical four-way power dividers are printed on the bottom of the lower substrate to form an in-phase feed network to excite the horizontally polarized radiated waves,and Wilkinson power dividers are used to extend the frequency bandwidth.Test results show that the dual-polarized antenna has a-10 d B impedance bandwidth range of 2.99 GHz to 4.7 GHz(44.4%)and 3.53 GHz to 3.87 GHz(9.2%)for vertical polarization and horizontal polarization,respectively,with port isolation greater than 35 d B,radiation efficiency higher than 80%,and cross-polarization level below-10 d B.The proposed antenna is suitable for 5G networks because of its compactness,broadband,high port isolation and dual polarization.Meanwhile,an omnidirectional antenna operating in 5.8GHz band is also simulated and optimized and tested using this antenna structure,and the test results are basically consistent with the simulation results.