This paper focuses on a tutorial overview of defected ground structure (DGS). The basic conceptions and transmission characteristics of DGS are introduced and the equivalent circuit models of varieties of DGS units are also presented. Finally, the main applications of DGS in microwave technology field are summarized and the evolution trend of DGS is given.

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An Overview on Defected Ground Structure

A novel compact dual-band electromagnetic band-gap (EBG) structure is proposed in this paper. The major contribution to this dual-band design is using cascaded mushroom-like units which operate at different frequencies. The position of via is moved off the center of the metal patch to get a lower resonant frequency and the effects of the radius of via are considered at the same time. The method of suspended microstrip is utilized to measure the band-gap characteristics of the EBG structures. Several dual-band EBG structures are designed and compared. Results show that this novel cascaded structure offers additional flexibility in controlling the frequencies of the stopband over a wide range. The cascaded dual- band EBG structure has potential application to dual-band antenna and circuit.

A Novel Design Approach for Dual-Band Electromagnetic Band-Gap Structure

Modal propagation characteristics of EM waves in ternary one-dimensional plasma photonic crystals

We applied the principles of photonic crystal devices to the millimeter wave portion of the electromagnetic spectrum. For the lens, we have observed their collimation and imaging ability both shown in the amplitude and phase. The results described in the report shown that the diffractive photon crystal lens is a perspective candidate to subwavelength focus lens in different area of applications, including microscopy, lens array element, etc.

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Subwavelength Diffractive Photonic Crystal Lens

A novel broadband design of a printed dipole antenna using PBG (photonic band-gap) structures is proposed and studied in the electromagnetic scattering. The high surface impedance and a frequency gap are used to reduce RCS (radar cross section) across needed frequency range (3.7–4.5 GHz). Because the high surface impedance restrains the surface waves, the obtained results show that RCS is reduced by 15 dB at resonance frequency and radiation characteristics of the antenna at operating frequencies are improved. The method of RCS reduction is suggested, and experimental results are presented.

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Scattering analysis of a printed dipole antenna using pbg structures

�H by extending Bloch theorem to the vector field Maxwell equations, the characteristics of 2-D dielectric rod array with square cross-section elements arranged in square lattice is analyzed in detail. From the numerical results, empirical expressions for both the relative bandwidth of frequency band gap and the midgap frequency with respect to the average permittivity, under the optimal filling fraction of dielectric/air in cross-section for wider bandwidth, are formulated by means of data fit.

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W. X. Zhang

Papers

Study on Bandwidth of 2-D Dielectric PBG Material