The Study Of New Antennas Based On Metamaterials

Left-handed material is a kind of novel manmade electromagnetic material, whose permittivity ε and permeability μ are simultaneously negative. Different from those of the electromagnetic wave propagating in a traditional, the electric field, magnetic field and wave vector of a electromagnetic wave propagating in a left-handed material satisfy the left-hand rule, which means that the phase and group velocity are in the opposite directions. So they have many unusual properties, such as negative refractive of light, reversed Cherenkov radiation, the perfect lens effects and etc. The recently reported LHMs can be classified into two different types according to the implementations. One is based on the modified or inherited resonant structures of the metallic rod (ROD) and the split resonant ring (SRR), the other is with the composite right/left-handed transmission line (CRLH TL) structures.In the beginning, this paper introduces the basic theory, the exotic characteristic, the parameter retrieval algorithm and the implementing form of the left-handed material in details. The electromagnetic characteristics of the SRR which is a main constitute of left-handed material and its complementary structure CSRR are studied and their electromagnetic parameters are retrieved using the S-parameter method proposed by Smith, validating that SRR and CSRR have almost the same resonant frequency and that SRR can realize negative permeability while CSRR can realize negative permittivity. On this base, the CSRR is applied to the microstrip antenna design. A novel method for designing dual-band mircostrip antenna is proposed with CSRR embedded in the ground plane of a conventional microstrip patch antenna., one working band produced by the patch itself while the other working band stimulated by the resonant CSRR. The energy is radiated out with the help of the patch. Two implementing ways of realizing the dual-band antenna are brought forward with different number of CSRR at different positions of the ground plane. The return loss and radiation patterns of the antennas as well as the effect of each parameter on the antennas are analyzed by simulated software HFSS and both antennas are validated by experiments to have good performance during their working bands. The novel method for designing dual-band patch antenna is proofed to be doable.A novel tri-band microstrip antenna is proposed with double layer microstrip structure based on CSRR. In the design, a tri-band is realized easily by skillfully make use of the interaction between different layer of metals and the CSRR. The characteristics of the tri-band antenna are analyzed in detail as well and the novel method for designing tri-band patch antenna is approved to be viable, too.Finally, the theory of zeroth resonant antennas is particularly recommended based on which a zeroth resonant antenna working at1800MHz is proposed. The proposed antenna has monopole like radiation patterns during its working band and its simulated maximal gain is1.34dBi. The zeroth resonant antenna has the advantages of compact in size, simple in structure, easy to fabricate and low in cost.