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1.
The EM nature of transmission zeros in microstrip structures has been the subject of several discussions. A liquid crystal thermal mapping technique is used for detecting the magnetic field distribution inside rectangular structures at the frequencies of the transmission zeros. In this way a perceptible evidence is given to previous theoretical results, which have pointed out the existence of two types of transmission zeros, called modal zeros and interaction zeros. 相似文献
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Montejo-Garai J.R. Ruiz-Cruz J.A. Rebollar J.M. Padilla-Cruz M.J. Onoro-Navarro A. Hidalgo-Carpintero I. 《Microwave Theory and Techniques》2005,53(5):1636-1642
In this paper, an extension to the extracted pole technique for synthesizing N-order filters with N-transmission zeros at real frequencies is presented. In addition, a new bandpass rectangular waveguide H-plane low-cost configuration filter for high-power low-loss application (patent pending) that implements a filtering function with finite real frequency transmission zeros is proposed. This structure operates as a resonant cavity in transmission at central frequency of the bandpass and simultaneously introduces a controlled transmission zero out of the bandpass. Since every double-controlled electrical behavior cavity introduces a transmission zero, it is possible to introduce as many transmission zeros as the order of the filtering function. In order to validate the synthesis procedure and the new structure, different filters have been designed: a second-order filter with two transmission zeros, a third-order filter with one transmission zero, a fourth-order filter with two transmission zeros, and finally, an eighth-order filter with two transmission zeros. The last two have been manufactured, showing an excellent agreement between the measurement and theoretical simulation. 相似文献
3.
《Microwave Theory and Techniques》2005,53(7):2411-2415
A simple design technique is introduced for generalized Chebyshev filters with asymmetrically located transmission zeros. The efficient and exact procedure is given for the calculation of transmission zeros for a class of generalized Chebyshev low-pass prototype filters with a maximum of four asymmetrically located transmission zeros of any multiplicity. This technique is based on obtaining the frequencies of magnitude characteristic extreme values in closed form, and after this, transmission zeros can be calculated by solving a system of nonlinear equations. Novel formulas for orders of zeros of maximally selective filters with equiripple characteristics in the passband and stopband are deduced. The obtained results are verified and illustrated by given examples. 相似文献
4.
《Microwave Theory and Techniques》1980,28(9):1018-1028
A novel synthesis technique is developed for two-port networks which possess finite real frequency transmission zeros. The low-pass prototype is synthesized in the form of a network with complex conjugate symmetry where the real frequency transmission zeros are extracted from both ends and realized by simple resonators separated by phase shifters. The remaining transmission zeros are realized by the central part of the filter in the form of a cross-coupled double array. This prototype is particularly suitable for designing waveguides bandpass filters and each real frequency transmission zero is independently tunable. Furthermore, in the case of the most complex transfer function with all possible types of transmission zeros, the realization requires only one type of coupling which is necessary in the important case of TE/sub011/ cylindrical mode cavity resonators. The general synthesis technique is given and the process illustrated by a nontrival example. Additionally, from the results of a computer program based upon the synthesis techniques, the important differences between the possible prototype forms for the same transfer function resulting from extracting the transmission zeros in different orders are cited. 相似文献
5.
传输零点的确定是交叉耦合滤波器综合的最基本要素.本文利用广义Chebyshev函数的极值特性以及滤波器阶数与传输零点最大值的关系,提出了一种根据滤波器特性指标同时确定广义Chebyshev滤波器的阶数和传输零点位置的方法,弥补了传统方法中传输零点确定的人为随意性,在满足技术指标条件下,实现了广义Chebyshev滤波器阶数最少,传输零点位置最佳.几个数值实验显示了该方法的过程和有效性. 相似文献
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Yong-Zhong Zhu Yong-Jun Xie He Feng 《Microwave and Wireless Components Letters, IEEE》2008,18(5):317-319
It is well known that an N-order coupling network with source-load coupling can realize a maximum number of transmission zeros equal to N. However, in the letter, by utilizing open-circuited stubs and increasing the velocity ratio, a novel two-pole hairpin filter can obtain three transmission zeros, which can improve selectivity in the lower stopband. The filter is analyzed extensively by using the relations between the types of coupled microstrip lines and transmission zeros of transfer response. Good agreement between measured and simulated data has been demonstrated. 相似文献
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Dong Suk Jun Hong Yeol Lee Dong‐Young Kim Sang Seok Lee Eun Soo Nam 《ETRI Journal》2005,27(5):643-646
This letter proposes a band‐pass filter (BPF) with two transmission zeros based on a combination of parallel coupling and end coupling of half‐wave transmission lines. The fabricated BPF exhibited a narrow bandwidth and two transmission zeros near the pass‐band due to the end‐coupled and shielding waveguide. At the center operation frequency of 60 GHz, the 20 dB bandwidth of the BPF is 1.0 GHz, which is almost 2% of the center operation frequency, and the insertion loss is 3.12 dB. Two transmission zeros reach approximately 40 dB at 58.5 and 62.5 GHz. The simulation results almost agree with the measured results. 相似文献
10.
A tunable planar combline filter exhibiting multiple transmission zeros is reported in this letter. By introducing two new coupled lines, the source/load-multiresonator coupling phenomenon is obtained without using additional combline resonators. The transmission zero locations can be adjusted by means of the length of these coupled lines to improve the upper stopband rejection. Moreover, all of these transmission zeros can be tuned at the same time as the passband without distorting the filtering-response shape. Parasitic coupling effects of the proposed filter topology and guidelines for their compensation are also discussed. The described combline filter is experimentally validated with the design and manufacture of a three-stage electronically-tunable prototype with five transmission zeros. 相似文献
11.
Chao-Huang Wu Yo-Shen Lin Chi-Hsueh Wang Chun Hsiung Chen 《Microwave and Wireless Components Letters, IEEE》2005,15(9):579-581
A compact coupled-line bandpass filter with multiple capacitive cross-couplings to create four transmission zeros is proposed. The locations of transmission zeros can be adjusted by varying the values of cross-coupled capacitances so as to improve the filter selectivity. The proposed filter is based on one-eighth-wavelength (/spl lambda//8) coupled-line sections and quarter-wavelength (/spl lambda//4) resonators, thus it occupies only half of the circuit area comparing with the conventional coupled-line bandpass filters. Specifically, a fourth-order microstrip coupled-line bandpass filter centered at 2.46GHz with a 3-dB bandwidth of 10.2% and four transmission zeros is implemented and examined. 相似文献
12.
An efficient design procedure for generalized Chebyshev filters with asymmetrically located transmission zeros is presented in this paper. The exact and simple procedure is given for the calculation of transmission zeros, for a class of generalized Chebyshev low-pass prototype filters with a maximum of three asymmetrically located transmission zeros of any multiplicity. This procedure is based on finding the frequencies of magnitude characteristic extreme values in closed form. New formulas for orders of zeros of maximally selective filters with equi-ripple characteristics in the pass-band and stop-band are deduced, and these are very useful in the design procedure. The obtained results are verified and illustrated by corresponding examples. 相似文献
13.
提出了一种新型的传输零点可控的微带带通滤波器结构,它由一段低阻抗线和与之相连的平行耦合线构成。通过调节低阻抗线与平行耦合线的偶模阻抗比,可以改变谐振器的2个模式之间的距离,从而灵活的调节滤波器的带宽;而通过调节平行耦合线的间距,则可以方便的调节传输零点的位置。仿真与实测结果都表明该滤波器具有良好的性能:低插损,结构紧凑,可以灵活的调节带宽和传输零点的位置。 相似文献
14.
The synthesis of N-order filters with N transmission zeros at real frequencies by means of extracted poles is presented. A procedure to extract the circuit elements that implement the finite insertion losses for infinite frequency is explained. To verify this procedure, three different implementations of a fourth-order filter with four transmission zeros are presented. 相似文献
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In this letter, a miniaturized planar two-pole microwave filter with two transmission zeros is presented. The building block of this filter is a high-Q double spiral slot resonator backed by a conductor plane. The provision of a float back conductor plane allows vertical integration of this filter with other passive and active RF electronic components usually found in miniaturized wireless transceivers. The conductor plane also provides a coupling mechanism between the input and output of the filter giving rise to transmission zeros. It is shown that the location of transmission zeros can easily be adjusted and significant out-of-band rejection be achieved using only two miniaturized double-spiral resonators. The design procedure and fabrication of a two-pole filter operating at 2.11GHz is demonstrated and a very good agreement between measured and simulated results is shown 相似文献
17.
Zlatoljub D. Milosavljevic Miodrag V. Gmitrovic 《Circuits, Systems, and Signal Processing》2002,21(2):195-205
In this paper, a complete procedure is presented for the synthesis of a class of generalized Chebyshev filters with a maximum of four real transmission zeros of any multiplicity, having an equiripple characteristic in the passband and the stopband, and maximum selectivity. The frequencies of magnitude characteristic extreme values in the stopband are calculated in the closed form. The transmission zeros are obtained by solving a set of nonlinear equations. New formulas for orders of zeros of maximally selective filters are deduced, and these are very useful in the design procedure. 相似文献
18.
滤波网络传输函数的零点、极点位置对滤波性能起着决定作用。全极点滤波器的所有衰减极点都位于DC和∞处。如果将传输零点放在S面有限频率处,则会形成特殊频率响应:虚轴上(实频)的传输零点,可形成准椭圆函数的陡降幅频响应;而实轴上(虚频)的和复数(实部非零)传输零点则起到类似时延均衡网络的作用,实现线性相位传输响应。在对不同文献关于传输函数的理论表述进行分析后,总结了传输函数、特征函数以及滤波网络综合中的一些重要概念,给出了几种典型函数的极点分布图对比,提供了几种运用特殊的传输零点放置来实现特殊滤波响应的设计应用。 相似文献
19.
Lowpass filters for data transmission with and without finite imaginary-axis transfer zeros are considered. The transfer-function poles adjust the equidistance between the rectangular pulse response zeros and the minimum intersymbol interference is automatically attained. The improvement in filter selectivity is provided by the imaginary-axis zeros. 相似文献
20.
Hong-Ming Lee Chih-Ming Tsai 《Microwave Theory and Techniques》2005,53(9):2812-2818
The transmission zeros of two coupled-microstrip circuits are studied in this research. Estimates for the frequencies of transmission zeros are given. A new concept of effective even- and odd-mode characteristic impedances is introduced. Useful design equations are given for improving the passband responses that are inherently distorted by different mode velocities. Finally, two filters with different topologies are designed for their zeros to be at the frequencies of the spurious harmonics and, thus, yield wide out-of-band rejections. 相似文献