In order to test the influence of the drop channel to its adjacent channels, we input three adjacent channels which satisfy the specification of the 100 GHz DWDM system. Figure 7 shows three channels in the tunable range (1543-1546 nm) without drop any one. Then we drop the middle of the three channels, and the Figure 8 shows the measured spectrum.From the Figure 8 we can see that the drop channel has not any damnification to the adjacent channels, and the adjacent channel isolation degree N is more than 35-dB. CONCLUSIONSIn this article, we have developed a novel stack of 100 GHz DWDM four cavities interference narrowband thin film angletuned filter and a novel three-port tunable filter. It has a simple structure, stable transmission characteristics, simple light path and it is easy to be fabricated. As the novel stack is optimized, the tunable filter has eliminated the phenomenon of polarization light central wavelength separation and its polarization dependent loss is very low (Ͻ0.1-dB). The experiments demonstrate that its insertion loss is very low (Ͻ2-dB), its adjacent channel isolation degree is very high (Ͼ35-dB), and its effective tunable range of 26 nm. This device has a bright application opportunity for its flexibility, low cost, and wide tunable range. INTRODUCTIONThe electromagnetic band-gap (EBG) structures are periodical cells composed of metallic or dielectric elements. One of the most important properties of EBG structure is to prohibit the propagation of surface wave [1, 2]. Practical applications of EBG structure usually have difficulty in accommodating its physical size, because the period of EBG lattices has to be a half-wavelength at the band-gap frequency. This problem had not been solved until the mushroom-like EBG was proposed by Sievenpiper et al. [3]. Later on, several other novel EBG structures were presented such as uniplanar compact EBG (UC-EBG) [4] and fork-like EBG [5]. These structures have several advantages, such as compact size, low loss, and so on. They can be integrated with antenna to enhance the gain and reduce the backward radiation by suppressing surface wave and improving efficiency [6]. Alternatively, radiating element can be mounted above the EBG structure to form high impedance ground plane (HIP) [7]. However, because of their resonant nature, all of those structures are narrow band, which restricts them to be used in broadband application. The challenge is to produce an EBG structure with wide bandwidth.In this article, two kinds of mushroom-like EBG unit with different radius of via are cascaded to form a novel broadband structure. The effects of the radius of via and unit number on the band-gap are considered using direct transmission method [8]. The simulation and experimental results show that the band-gap of the broadband structure covers the stop-band of the two different uniform configurations with the radius of via changed. The bandgap is enlarged greatly which achieves almost 70%. MUSHROOM-LIKE EBG THEORY AND DIRECT TRANSMISSION METHODThe mushroom-like E...

This paper presents a synthesis technique of the dual offset shaped reflector antenna using Differential Evolution with Global and Local neighborhoods (DEGL) algorithm. The main reflector and subreflector are parameterized by Zernike polynomial expansion. With these expansion coefficients, the antenna is optimized to achieve a contoured beam covering the China territory in Ku-band. The performance of the antenna is calculated by Physical Optics (PO) and Physical Theory of Diffraction (PTD) techniques. The calculated results are validated by the commercial software GRASP9.3.01.

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