| Today’s mobile and wireless communication devices are used in almost allimaginable environments, such as in cell phone, in cars, in talking position near thehead. The environment of the antenna and the resulting field distribution around ithas unfortunately an eminent impact on its impedance. And the mismatch betweenantenna and source/transmitter reduces its power efficiency, linearity and lowers thepower of the input/output signal. Moreover, maximum power is expected to transmitto the antenna to achieve maximum transmission efficiency. So the goal of obtainingfast antenna tuning systems, which are capable of offering impedance matching (IM)with changing load and environmental aspects, has become increasingly significant.In order to reduce RF antenna energy reflection and increase the powertransmission efficiency, an adaptive impedance matching method based on particleswarm optimization has been proposed in the paper. Its primary work is shown asfollows:Firstly, on the basis of the existing achievements, this paper uses the π typematching network which ensure maximum power transfer between the load andsource compose with the variable capacitor and variable inductance in Section2.Compared with many traditional matching networks, this π type matching networkwhich does not exist matching restricted areas can get very accuracy matchingresults and fast matching speed because of the simple topology.Then, a new parallel adaptive quantum particle swarm optimization algorithm isproposed in Section2in order to solve the problem that standard particle swarmoptimization(PSO) algorithm may easily trap into local optimal points and maydifficultly obtain exact solutions at the late of the iteration. By sharing the twoextreme values of the particles, the proposed method enables to adaptively searchtheir optimum solutions in parallel by combination of an improved adaptive PSOwith a quantum Particle Swarm Optimization of boundary variation. It is provedeffectively to overcome the shortcomings of standard PSO. Test results show that theaccuracy and the velocity of global search for optimal solutions have been greatlyimproved.Moreover, in RF ranges, a simple single frequency adaptive impedancematching methods are presented in Section3, their are all ideal tuning methods. The RF narrowband impedance matching can be considered as the impedance matching atthe center frequency of the bandwidth range because of the high-Q property of thecircuit. The broadband antennas are capable to provide modern communicationsystems employing frequency hopping and spread spectrum techniques. The RFbroadband impedance matching can be applied at different frequency bands, such ascellular communications at900and1800MHz, global positioning system (GPS) at1.2and1.5GHz, and Bluetooth and WiFi at2.4and5.2GHz.Next, due to high operation frequency, as well as low voltage and small sizetrend, the non-ideal factors of impedance matching network are considered. It iscrucial to be able to evaluate such power loss in the design and analysis of matchingnetworks for budgeting system power. In Section4, an adaptive impedance matchingtechnique considering the influence of parasitic loss effects and power loss and usingsimple model and IC model is presented. Then we analyze on-chip inductor model’ssensitivity and simplify impedance matching structure, simulation results show thatthe proposed method achieves the same effect of power loss as the real complexcircuit, and consuming time is effectively reduced.Finally, the practical system of adaptive impedance matching network isimplemented to contain a variety of module, such as variable capacitor, variableinductance, detection module. The simulation is achieved by SLPS technology.Aiming at existing MATLAB platform, the friend human-computer interactioninterface is designed. |
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