| Microstrip patch antennas(MPA)are widely used in various wireless communication devices.However,the low gain of MPA limits the application in long-distance wireless communication.High-Order Mode resonance technology and Resonant Cavity Antennas(RCAs)provide methods for improving the gain of MPA.Based on these technologies,thesis studies the gain enhancement of MPA.The main research contents are as follows:Firstly,about poor broadside directivity of the TM12 in traditional rectangular MPA,the equivalent magnetic currents(EMCs)of this mode are analyzed.After shorting pins are added to traditional rectangular MPA,the change of EMCs is achieved,and the normalized radiation pattern with excellent broadside directivity is obtained by analysis and plotted.According to this conclusion,the simulation can obtain the corresponding electric field distribution,which improves broadside directivity and significantly enhances broadside gain.Theoretical result is basically consistent with the simulated results.A dualpolarized dual-band cross-shaped MPA with high radiation efficiency is proposed with this conclusion.The feed of the antenna is simple,and the size is 1.65?0×1.65?0×0.023?0 to achieve dual-frequency,dual-polarization,and the simulated broadside realized gain is higher than 11dB in the operating frequency,and the profile is low.It can be used in narrowband communication systems.Secondly,with the above-mentioned problems of narrow bandwidth and high cost of the proposed antenna,it is proposed to use FR4-epoxy layer and air layer as the dielectric material,and the superposition of three modes to operate at the same frequency to enhance broadside gain.Because there is strong couple between the two ports of this layer.A copper column is added in the middle of air layer to reduce coupling.The proposed antenna improves bandwidth and also achieves gain enhancement.The simulated results show that when the size is 2.29?0× 2.29?0× 0.069?0,the realized gain in the operating frequency band is better than 11.53dB,and the maximum realized gain is 12.59dB,the measured results show that the realized gain in the operating frequency band is better than 10.04dB,and the maximum realized gain is 12.05dB.Although the proposed antenna improved narrow bandwidth and high cost,the double-layer makes the antenna structure complex,and the loss tangent of FR4-epoxy is large,so single layer filled with air low cost dualpolarized high-gain cross-shaped MPA is proposed.The size is 2.7?0× 2.7?0× 0.084?0,the simulated maximum realized gain is 15.01dB,and the simulated realized gain is higher than 13.79dB in the operating frequency band.Finally,for enhancing the gain of high-isolation dual-polarized MPA,a Frequency Selective Surface(FSS)superstrate is added to the broadside direction of the MPA to form RCAs.The superstrate unit cell adopts symmetrical structure design,so that all radiation modes'gain of the MPA can be enhanced.The simulated results show that broadside realized gain is increased by 6.98-10.46dB in the operating frequency band.At the same time,the bandwidth has also been improved,from 3.26%to 5.62%. |
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