Research On The Application Of Capacitive Loading Method In The Design Of Mobile Phone Antenna

As an important part of the mobile terminal, mobile phone antenna has been a hottopic in the field of communications. Antenna trends of miniaturization,multi-frequency, broadband and the decoupling problem in the multi-antenna systemthat LTE brings all drive people to continuously explore in the field of antennaresearch.Application of the capacitive loading method is often mentioned in antennadesign, but generally speaking, there is no related specific discussion or detailedinstructions about its role. Aiming at this problem, on the basis of a summary of thecapacitive loading in the applications of antenna design, this paper does someverification and research on its role of additional parasitic patch, miniaturization of theantenna and improving the isolation among MIMO antenna units.At the beginning of this paper, lots of basics of the antenna are introduced. PIFAantenna which is popular currently is highlighted and the LTE antenna technologiesare also done some brief introductions. On this basis, a series of summary and analysisabout commonly used antenna technologies of miniaturization, multi-frequency,broad-band and decoupling technologies among MIMO antennas which is associatedwith LTE technology are put forward.Secondly, focus on the application of achieving multi-frequency and extendingantenna bandwidth of the additional parasitic patches, this paper analyzes andsummarizes the effect of the capacitive loading on the parasitic patch technology. Thencombining with PIFA antenna which is widely used nowadays, analyze the methodsand theories of the capacitive loading how to achieve antenna miniaturization. And on the basis of the above analysis, two kinds of capacitive loading miniaturized antennaswhich work on LTE700MHz band are designed respectively. The final simulationresults show that the antenna size is further reduced to about λ/8by the conventionalλ/4lengths and achieving the goal of miniaturizationof the antenna.Finally, a kind of capacitive loading dual-band high isolation MIMO antennawhich is working on LTE2300-2400MHz and LTE2570-2620MHz is designed byanalyzing the principles and methods of the capacitive loading on improving theisolation among antenna unites. This MIMO system is composed of two antennaelements. Every single unite uses PIFA antenna and the dual-band is achieved by usingmeandering stream technology. After loading the capacitive load patch and thecapacitive coupling feed patch, isolation between antenna elements is improvedsignificantly. Based on this type of antenna, then two kinds of d ual-band MIMOantenna that working in the same LTE frequency bands are designed respectively. Thepurpose is to verify the effectiveness of the proposed capacitance loading method andthe pure capacitive load loading in improving the isolation between MIMO antennaelements.