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1、 外文翻译题目：紧凑的高阶谐波抑制Compact Multi-harmonic harmonic suppression Compact Multi-harmonic suppression LTCC Bandpass Filter Using Parallel Short-Ended Coupled-Line Structure Xu-Guang Wang, Young Yun, and In-Ho Kang This paper presents a novel simple filter design method based on a parallel short-ended coup
2、led-line structure with capacitive loading for size reduction and ultra-broad rejection of spurious passbands. In addition, the introduction of a cross-coupling capacitor into the miniaturized coupled-line can create a transmission zero at the second harmonic frequency for better frequency selectivi
3、ty and attenuation level. The aperture compensation technique is also applied to achieve a strong coupling in the coupled-line section. The influence of using the connecting transmission line to cascade two identical one-stage filters is studied for the first time. Specifically, such a two-stage ban
4、dpass filter operating at 2.3 GHz with a fractional bandwidth of 10% was designed and realized with low-temperature co-fired ceramic technology for application in base stations that need high power handling capability. The measured and simulated results showed good agreement. Keywords: harmonic band
5、pass filter, LTCC. suppression, coupled-line, I. Introduction In recent years, compact, high-performance, and low-cost components for radio frequency (RF) applications have been the focus of a great deal of research and industrial pursuit with the explosive growth of modern wireless communication se
6、rvices. One promising method for many miniaturizing and packaging technologies is to use low-temperature cofired ceramic (LTCC) on account of its multilayer structure and high unloaded quality factor. The bandpass filter is an essential component in the RF front-end of communication systems. It pass
7、es the desired frequencies, rejects unwanted signals, and suppresses harmonics. However, as a result of the distributed characteristic of the transmission line, undesired spurious passbands or harmonics are a problem for conventional filters and can seriously degrade their performance, which may be
8、critical in certain applications. To find a way to suppress spurious responses, many studies have been carried out. Using the technique of photonic bandgap (PBG) and defected ground structure (DGS) is one of the most popular approaches. The PBG structure was initially proposed in the optical field,
9、and essentially comprises periodic etched defects on the back of a metallic ground plane which can provide effective and flexible control of the propagation of electromagnetic (EM) waves along a specific direction or in all directions. Since it was applied to microwave and millimeter frequency-band
10、applications, numerous novel PBG structures have been proposed for the design of both passive and active devices with the property of multi-harmonic suppressionHowever, Manuscript received July 6, 2008; revised Feb. 27, 2009; accepted Apr. 7, 2009. Xu-Guang Wang was with the Department of Radio Scie
11、nce & Engineering, Korea Maritime University, Busan, Rep. of Korea, and is now with the Department of Electronic Engineering, Sogang University, Seoul, Rep. of Korea. The DGS with periodic or nonperiodic arrays is another very practical approach because it can provide a rejection band in some freque
12、ncy ranges. Compared with the PBG structure, which needs many units to build a filter, the DGS is simpler because only a few units can be used to construct a filter, and this results in a smaller filter size. The rejection characteristic of the DGS is available to many microwave circuits, such as po
13、wer-amplifier modules, planar antennas, power dividers and filters, and so on . However, due to the periodic structure of the PBG and DGS, these filters suffer from their large circuit areas and specific circuit configurations, which seriously hinder their application to wireless communication syste
14、ms. In this paper, we propose a compact multi-harmonic suppression LTCC bandpass filter based on the capacitive loading of the parallel short-ended coupled-line structure. This is a relatively simple way of reducing the coupled-line electrical length, which usually plays a decisive role in the filte
15、r size. On the other hand, the use of lumped elements can effectively suppress the spurious passbands. In addition, the cross-coupling capacitor and aperture compensation technique are employed for better performance. Such a compact twostage bandpass filter working at 2.3 GHz with high power handlin
16、g capability was implemented in a multilayer LTCC substrate and examined carefully. Design Theory 1. Size Reduction Method Figure 1(a) shows the generalized bandpass filter structure to be miniaturized in this design. The admittance inverter, which is a quarter-wavelength transmission line with characteristic impedance Z0 = 50 ?, can be replaced with a lumped circuit as shown in Fig. Improvement of the Filter Performance The attenuation level at
