Tham khảo tài liệu 'microstrip antennas part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Artificial Materials based Microstrip Antenna Design 49 realized with periodic loading of conventional microstrip transmission lines with series capacitors and shunt inductors 12 20 . Many microwave circuits have been implemented by using this strategy such as compact broadband couplers broadband phase shifters compact wideband filters compact resonator antennas LH leaky wave antennas which have a very unique property of backfire-to-endfire frequency scanning capability with broadside radiation which is not possible for RH leaky wave antennas Caloz Itoh 2005 Eleftheriades Balmain 2005 . In this section the design of a novel microstrip dipole antenna by artificially engineering the substrate material with left-handed metamaterials LHM is explained for compact wideband wireless applications. The broadband microstrip antenna is composed of a dipole and six LHM unit cells. The antenna is matched to 50D with the stepped impedance transformer and rectangular slot in the truncated ground plane. By the utilization of phase compensation and coupled resonance feature of LHMs the narrowband dipole antenna is operated at broader bandwidth. First in Section the structure of the electrically small LHM unit cell is described. A one dimensional dispersion diagram is numerically calculated by Finite Element Method FEM to prove the lefthandedness and respective negative refractive index of the proposed unit cell. The effective permittivity and permeability are also retrieved from the reflection and transmission data of one unit cell. In Section the configuration and operation principle of the proposed antenna are explained. The simulated and measured return loss radiation pattern and numerically computed radiation parameters are presented. LHM unit cell design The negative material parameters are synthesized by the simultaneous excitation of electric and magnetic dipoles in the LHM unit cell. The original structure proposed in Smith et al. 2000 consists of a bulky .
