A new defected ground structure (DGS) for the microstrip line is proposed in this paper. The proposed DGS unit structure can provide the bandgap characteristic in some frequency bands with only one or more unit lattices. The equivalent circuit for the proposed defected ground unit structure is derived by means of three-dimensional field analysis methods. The equivalent-circuit parameters are extracted by using a simple circuit analysis method. By employing the extracted parameters and circuit analysis theory, the bandgap effect for the provided defected ground unit structure can be explained. By using the derived and extracted equivalent circuit and parameters, the low-pass filters are designed and implemented. The experimental results show excellent agreement with theoretical results and the validity of the modeling method for the proposed defected ground unit structure.

A design of the low-pass filter using the novel microstrip defected ground structure

Preface 1. Introduction 2. FDTD Method for periodic structure analysis 3. EBG Characterizations and classifications 4. Design and optimizations of EBG structures 5. Patch antennas with EBG structures 6. Low profile wire antennas on EBG surfaces 7. Surface wave antennas Appendix: EBG literature review.

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Electromagnetic Band Gap Structures in Antenna Engineering

A novel waveguide using a photonic bandgap (PBG) structure is presented. The PBG structure is a two-dimensional square lattice with each cell consisting of metal pads and four connecting lines, which are etched on a conductor-backed Duroid substrate. This uniplanar compact PBG structure realizes a magnetic surface in the stopband and is used in the waveguide walls to provide magnetic boundary conditions. A relatively uniform field distribution along the cross section has been measured at frequencies from 9.4 to 10.4 GHz. Phase velocities close to the speed of light have also been observed in the stopband, indicating that TEM mode has been established. A recently developed quasi-Yagi antenna has been employed as a broad-band and efficient waveguide transition. Meanwhile, full-wave simulations using the finite-difference time-domain method provide accurate predictions for the characteristics of both the perfect magnetic conductor impedance surface and the waveguide structure. This novel waveguide structure should find a wide range of applications in different areas, including quasi-optical power combining and the electromagnetic compatibility testing.

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A novel TEM waveguide using uniplanar compact photonic-bandgap (UC-PBG) structure

This work describes the integration of commercially available packaged radio frequency microelectromechanical system (RF MEMS) switches with radiation pattern reconfigurable microstrip antennas. Most applications of RF MEMS switches consider the switches as only circuit elements. In contrast, the implementation of packaged switches in this particular antenna must address not only the simple open/closed behavior of the switches but also their impact on the radiation characteristics of the reconfigurable antenna. Here, two Radant MEMS single-pole single throw (SPST) SPST-RMSW100 (packaged RF MEMS) switches are used to reconfigure the radiation patterns of a resonant square spiral microstrip antenna between endfire and broadside over a common impedance bandwidth. Switch insertion, matching network design, and other issues are addressed. Results for both simulated and measured antennas, as well as recommendations for future work in this area, are provided.

Integration of packaged RF MEMS switches with radiation pattern reconfigurable square spiral microstrip antennas

Surfaces act as perfect magnetic conductors (PMC) if the phase shift of the reflection of an electromagnetic wave amounts to 180/spl deg/ compared to the reflection at a perfect electric conductor (PEC). One possibility to create PMC surfaces artificially is an array of closely spaced patches. In this paper, based on the relation between PMC surfaces and patch antennas, an explanation for the functioning of this artificial PMC is given. An equivalent network is derived that allows to understand the functioning and to provide a starting design for a numerical optimization by aid of fullwave methods. A planar PMC is used for the first time as a reflector for a large aperture coupled patch antenna array, especially in order to reduce the parallel-plate modes that are usually present in traditional aperture coupled patch arrays. An additional sidelobe suppression of over 6 dB has been achieved by the planar PMC reflector in comparison to a traditional reflector.

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Planar artificial magnetic conductors and patch antennas

The realisation of a magnetic conducting surface using a novel two-dimensional uniplanar photonic bandgap structure is described. This novel idea is verified by measured results and the results obtained using the finite-difference time-domain method.

Realisation of magnetic conducting surface using novel photonic bandgap structure

Single- and double-layer grid array antennas are numerically investigated. A radiation beam normal to the antenna plane is realized by using appropriate configuration parameters. The difference of the gains between the upper-fed and lower-fed grid arrays is very small (0.5 dB over a frequency range of 12.5 to 12.75 GHz).

Center-fed grid array antennas

Square loop, meander dipole and spiral antennas printed on grounded dielectric substrates, are numerically analysed using Sommer-feld type integrals. The square loop is found to have a radiation pattern in which cross-polarisation is negligible and zero in the E-plane and the H-plane, respectively. The results obtained for the meander dipole demonstrate that such an antenna can be made small with no deterioration in the radiation pattern. The analysis of the spiral antenna fed from the outer arms shows that the spiral can radiate a circularly polarised wave with a purely resistive input impedance.

Numerical analyses of printed line antennas

An Archimedean spiral antenna, two arms of which are located above a conducting plane reflector at a small height, is numerically analyzed. Resistive loads are used to reduce standing wave currents on the arms. At the lowest frequency (the antenna height corresponding to one-twentieth the wavelength), the spiral shows a gain of approximately 3 dB with an axial ratio of approximately 4 dB. >

A low profile Archimedean spiral antenna

A dual-loop slot antenna consisting of two identical loops fed by a triplate line is proposed. It is experimentally demonstrated that the antenna radiates a unidirectional beam of linear polarisation. It is also shown that the generation of a circularly polarised wave is possible by adding perturbation elements to the loops.

Kazuhide Hirose

Papers

Realisation of magnetic conducting surface using novel photonic bandgap structure

Center-fed grid array antennas

Numerical analyses of printed line antennas

A low profile Archimedean spiral antenna

Dual-loop slot antenna with simple feed