Research On Compact Microstrip Antenna Array

Antennas are indispensable for a wireless communication system.With the small-sized tendency of communication system,the size of antennas should be synchronously reduced to satisfy with the finite space.Because of the low profile,simple and inexpensive fabricate using printed-circuit technology and versatile in terms of radiation patterns,microstrip antenna arrays are used for many applications.It is a really practical study subject to reduce the size of microstrip antenna arrays without the deterioration of system performance.What's more,feeding networks play an important role for antenna arrays.The dimension of feeding network should also be reduced to match the miniaturized antenna array.Centre on the topic of compactness,a decoupling network for ultra-compact microstrip antenna array and miniaturized feeding network with phase shifter are studied.The specific contents are listed as follows:1.Introduced the basic theories of microstrip antennas and antenna arrays,including radiation mechanism and the generation of surface wave and surface currents;the working theory of microstrip antenna arrays;introduced the theory of mutual coupling between array units.This part has laid the fundamental for the following works.2.An ultra-compact microstrip antenna array operating in 2.4GHz is proposed.In this design the inset microstrip line feeding method which can avoid the impedance transformer increasing the size is employed for the units.The edge-to-edge distance between two units is 0.16(?g is the wavelength in substrate at operating frequency)to realize the compact size.An inter-digital resonator decoupling network is loaded,which can greatly decrease mutual coupling between adjacent patches.The experiment and simulation results show that the antenna array has an impedance bandwidth of 8.34%.At operating frequency,the S12 reduced from-14 dB to-40 dB.And the gain of unit can reach to 1.9dB,the 3dB beam width in E-plane and H-plane are 85° and 78°respectively.The experimental results show good agreement with simulations,demonstrating good performance of the decoupling network.The designed antenna array can be applied to MIMO,phased arrays and so on.3.The applied research of Composite Right/Left-Handed Transmission Line(CRLH-TL).According to the antenna array aforementioned,a phase shifter which can achieve negative phase shifting is designed based on the phase characteristics of CRLH-TL.At the same time,T-junctions are employed for power splitting.Finally,a miniaturized 1:3 feeding network with CRLH-TL phase shifter is proposed.The simulated and measured results demonstrate that the feeding network can obtain equal-amplitude and in-phase EM signals in the frequency range from 2.35 GHz to 2.42 GHz.When the feeding network is applied to the antenna array,the experimental results show good agreement with simulations,demonstrating the value of application of the design.