Study On Design And Measurement Methods For Small Antennas

With the great development of wireless communication, the demand of antenna design becomes more and more rigorous, especially in the applications of communications such as mobile phone, RFID and blue tooth. More studies focus on compact antenna with multi-band and application of multi-antenna. Further more, there comes many difficulties of the measurement of small antennas.Firstly, analytic methods for small antennas and their applications are introduced, in which PIFA and dipole antennas are emphasis. Some applications of small antennas are presented with some new telecommunication technologies, such as Bluetooth, RFID and ZigBee.Secondly, a multi-band, dual-antenna system is designed and simulated with professional electromagnetic simulator. First of all, a novel PIFA is proposed and its prototype is used in the dual-antenna system. Then, concrete analysis of antenna performance is given when the parameters of antenna are changed. In terms of the dual-antenna system, coupling effect between two antennas is a key point to consider. To reduce the coupling effect, the prototype of single PIFA is rearranged. Simulation results show that the dual-antenna system can work in four frequency bands and the maximum of coupling effect between two antennas is less than -10dB.Finally, a design concept of the planar testboard is proposed aiming at solving the problem of difficult test of RFID tag antennas. A practical testboard is designed and manufactured. The good agreement between the simulation and the measurement results shows that the testboard can be used to test the input impedance, radiation patterns and gains of the meander-line dipole tag antenna accurately, which also provides a testing scheme to other small-size antennas with balanced feed.