一种适用于高速电路中SSN抑制的紧凑型电磁带隙新结构

该文根据电磁带隙(EBG)结构的带隙形成机理以及共面EBG结构的等效电路,提出了一种适用于高速电路中同步开关噪声(SSN)抑制的紧凑型EBG结构,使用Ansoft HFSS对该结构进行仿真分析。仿真结果表明在抑制深度为-30 dB时,阻带范围为0.6-6.4 GHz,阻带带宽为5.8 GHz,与传统的L-bridge结构相比,阻带带宽增加了1.8 GHz,相对带宽增加了45%,实现了较低的带隙中心频率以及较宽的阻带带宽,并用Ansoft Designer通过时域仿真验证该结构具有较好的信号完整性。     

EBG combined isolation slots with a bridge on the ground for noise suppression

In this paper, a coplanar electromagnetic bandgap (EBG) structure is presented to realise with L-bridge unit cell on the power plane that is combined isolation slots with straight/meander-bridge on the ground plane. The proposed structure with meander-bridge on the ground plane possesses an ultra-wide band gap from 0.22 GHz to 20 GHz with isolation below ?30 dB, which is remarkable better than traditional EBG. The lumped equivalent-circuit model for the structure is presented and analysed to explain the mechanism of the improvement of noise suppression. The cut-off frequency for the proposed structure is obtained by theoretical analysis. It is shown that the increase of equivalent inductance of the bridge influences the cut-off frequency. The meander-bridge on the ground plane is adopted to broaden the stopband and significantly enhance the suppression depth. The validity of the presented structure is verified by the simulation compared to the measurement.     

On EBG Structures for Cellular Phone Applications

Electromagnetic Band Gap (EBG) materials exhibit many interesting features for microwave and millimetre wave applications. Recently, the employment of such materials has been proposed for cellular phone applications in order to limit the back-radiation and to prevent the exposure of the user from the electromagnetic field. In this paper, we first present a new way to synthesize EBG structures suitable for very compact layouts and then we apply the technique to verify the attractive features of EBGs in cellular phone applications. We show that the suppression of the surface waves, due to the high impedance behaviour of the EBG materials, does not avoid back-radiation from a cellular phone. Nevertheless, EBG structures permit to improve both the radiation efficiency and the impedance bandwidth of terminal antennas.     

Partial EBG Structure with DeCap for Ultra‐wideband Suppression of Simultaneous Switching Noise in a High‐Speed System

To supply a power distribution network with stable power in a high‐speed mixed mode system, simultaneous switching noise caused at the multilayer PCB and package structures needs to be sufficiently suppressed. The uniplanar compact electromagnetic bandgap (UC‐EBG) structure is well known as a promising solution to suppress the power noise and isolate noise‐sensitive analog/RF circuits from a noisy digital circuit. However, a typical UC‐EBG structure has several severe problems, such as a limitation in the stop band's lower cutoff frequency and signal quality degradation. To make up for the defects of a conventional EBG structure, a partially located EBG structure with decoupling capacitors is proposed in this paper as a means of both suppressing the power noise propagation and minimizing the effects of the perforated reference plane on the signal quality. The proposed structure is validated and investigated through simulation and measurement in both frequency and time domains.     

一种具有超宽禁带的S-CSRR新型电磁带隙结构

研究了高速电路领域电源/ 地平面之间的电源完整性问题,并设计出在电源地平面之间加载的一种新型“S”形互补开口谐振环(S鄄CSRR)电磁带隙结构,用以有效阻止同时开关噪声在电源分配网络上的传播。以抑制深度-30 dB 为标准,能够得到高达9 GHz 的超宽禁带,明显优于传统的“L”桥型电磁带隙结构。在电磁干扰方面,空间辐射电场的实验结果显示,在部分频段,该新型电磁带隙结构相比无电磁带隙结构的参考板具有更低的电磁干扰。此外,文章还探讨了该电磁带隙结构作为电源平面时的信号完整性问题。研究表明,在这种结构上采用差分线传输信号,对信号完整性的影响较小。     

A tiny EBG‐based structure multiband MIMO antenna with high isolation for LTE/WLAN and C/X bands applications

This article proposes a compact multiple‐input multiple‐output (MIMO) antenna with the electromagnetic band gap (EBG) structures for mobile terminals. The proposed MIMO antenna is composed of two radiation patches in which diagonal and folded microstrip lines are utilized to control the frequency bands. The radiation patch, one EBG structure and a rectangular‐shaped ground plane are etched on both sides of the antenna. The EBG structures have been employed for reducing the mutual coupling between the antenna elements. As a result of the effect of these structures, the mutual coupling between the two elements is reduced by less than ?30 dB. The proposed antenna is implemented on an FR4 substrate with dimensions 20 × 10 × 1 mm³. According to measured results, frequency ranges of 2.2 to 3.6 GHz and 5.1 to 5.9 GHz with S₁₁ < ?10 dB and also 3.7 to 5 GHz and 8 to 12 GHz with S₂₂ < ?10 dB have been obtained. Moreover, measured S₁₂ and S₂₁ with values of less than ?30 dB for both Ports have been realized. Additionally, the envelope correlation and radiation efficiency of the purposed antenna are less than 0.09 and more than 82%, respectively.     

Bandgap analysis of 2D photonic crystals with Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method

In this paper, an accurate and rapid method is presented to characterize bandgaps of photonic crystals (PCs) constituted by two-dimensional (2D) arrays of dielectric rods with rectangular and circular cross sections. The transmittance and reflectance spectrums of finitely periodic 2D PCs are analyzed using the combination of Rigorous Coupled Wave Analysis (RCWA) and Generalized Scattering Matrix (GSM) methods. In the proposed method, band-edge frequencies of infinitely periodic 2D PCs are determined via Auxiliary Functions of Generalized Scattering Matrix (AFGSM) method using RCWA as a sub-block code. Numerical investigations show that estimating the band-edge frequencies of ideal 2D PCs via AFGSM method is identical with determining the bandgaps of the finite periodic global structure. The high convergence rate of the proposed technique also allows us to perform a bandgap characterization including the higher order Floquet modes without solving the eigenvalue equations for each cascaded layer. Furthermore, the variation of bandgaps when modifying the incidence angle, physical and geometrical parameters are presented for both TE and TM polarizations. The effect of introducing defect in 2D PC structure and resulting band natures are outlined. Our results are in excellent agreement with both theoretical and experimental results in the literature.     

Metamaterial inspired fabric antenna for wearable applications

A compact and robust fabric antenna incorporated with metamaterials (MTM) at 2.4 GHz is introduced for wearable devices application where the MTM behaves as EBG/AMC. The benefit of introducing MTM in a wearable antenna is to diminish the influence of frequency detuning and reduces the backward radiation specifically when loaded on the human body. The overall size of the presented antenna incorporated with MTM is 60 × 60 × 2.4 mm3. Furthermore, the integrated design has the capability of controlling Specific absorption rate (SAR) and improved the bandwidth, front‐to‐back ratio (FBR), and gain up to 14.5%, 13.7dB, and 7.5dBi, respectively. The operations under different bending diameters on real and modelled human body are studied. Compared with conventional antennas, MTM‐inspired antennas reduce the SAR to safe levels of more than 90%. The presented integrated design can be a good candidate for incorporation into a variety of flexible systems for medical application.     

Design and analysis of multiband notched pitcher‐shaped UWB antenna

To mitigate the interference with coexisting wireless systems operating over 3.3–3.6 GHz, 5.15–5.825 GHz, and 7.725–8.5 GHz bands, a novel triple band notched coplanar waveguide fed pitcher‐shaped planar monopole antenna is presented for ultrawideband applications. Bands notched characteristics are achieved using a novel mushroom type electromagnetic band gap structure like resonator and a split ring slot. A conceptual equivalent RLC (Resistor‐Inductor‐Capacitor)‐resonant circuit is presented for the band notched characteristics . Furthermore, the input impedance and VSWR (voltage standing wave ratio) obtained from the equivalent circuit are validated with simulated and measured results. Performances of the antennas in both, the frequency domain and the time domain are investigated. The simulated and measured results demonstrate that the proposed antennas have wide impedance bandwidth, nearly stable radiation patterns, and suppression of gain and total radiation efficiency at notched bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:795–806, 2015.