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    Multi Wideband Hexagonal-Spiral Microstrip Band-Pass Filter for Wireless Applications
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    Abstract:
    In this communication, multi-wideband micro-strip Hexagonal-Spiral (HS)band-pass filter is presented. The proposed multiband band-pass filter consists of four spiral shunt quarter-wavelength short-circuited stubs separated by connecting lines with length of λg/2 and λg/4, respectively. Appropriate transmission zeros are generated to isolate the bands of proposed band-pass filter, as desired. From the simulated results, the offered wide bandwidth observed for dual band-pass filter is 240 MHz (0.8 GHz to 1.04 GHz) and 250 MHz (1.18 GHz to 1.43 GHz). The bandwidth for the proposed triple band pass filter are 220 MHz (0.64 GHz to 0.86 GHz), 100 MHz (1.38 GHz to 1.48 GHz), and 400 MHz (2.31 GHz to 2.71 GHz). The triple band HS filter is fabricated and tested with network analyzer. The measured results are in good agreement with the simulation results. These filters are suitable for GSM 900 MHz and WLAN (2.4 GHz) applications.
    Keywords:
    Wideband
    Multi-band device
    GSM
    A new method of designing re-entrant cavity bandpass filters is discussed. By using this method filters can be designed without any experimental trials. Filters are molded with identical outer dimensions over 4 to 8 GHz bands and mass produced. Their measurements coincide with theoretical results obtained by this new design method.
    Network synthesis filters
    Filtering theory
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    In this paper, a combined quasi-lumped-open-loop resonator (QL-OLR) is introduced and applied for filter design. The resonator can have single and dual-band behavior. Two bandpass filters as well as two dual-band bandpass filters have been designed, fabricated, and tested, that consist of two resonators each. The bandpass filters show the behavior of four return loss poles (fourth order filter), and by slitting these resonators a dual-band bandpass filter can be achieved (each band has two return loss poles). Transmission zeroes can be easily introduced into the filter response as well by utilizing the properties of both quasi-lumped and open-loop resonators
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    Electronic filter topology
    Return loss
    Butterworth filter
    Citations (4)
    Abstract This paper presents the design of frequency-tunable dual-band, tri-band and quad-band bandpass filters (BPFs). The proposed three BPFs can be independently tuned and individually switched by varying the capacitances of the varactors. In the designed tunable dual-band BPF (TD-BPF), common input/output feed lines are utilized for two tunable dual-mode resonators (TDRs). Further, three TDRs and four TDRs are employed to achieve tunable tri-band BPF (TT-BPF) and tunable quad-band BPF (TQ-BPF), respectively. Then, the TD-BPF and the TT-BPF are fabricated and measured to verify individual tunability and independent switchability. For the TD-BPF, the measurement results show that the center frequency (CF) of the first passband varies from 1.37 to 1.62 GHz, and the CF of the second passband varies from 2.3 to 2.64 GHz. In the measured TT-BPF, the tuning ranges of CFs of three passbands are 1.3–1.5 GHz, 2.36–2.6 GHz, and 3–3.54 GHz, respectively.
    Passband
    Multi-band device
    Center frequency
    Citations (4)
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    Realization (probability)
    Distributed element filter
    Elliptic filter
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    This paper reports on the design of a 24 GHz bandpass filter. This device is developed in a multilayer BCB-Si technology to ensure the development of the system on a unique chip. Moreover the technique of integration of semi-lumped lowpass filters in bandpass filter is used to reduce the global size and eliminate spurious response of the filter. The general method to design this kind of filters is described and experimental results are presented.
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    This paper proposes a compact dual-band bandpass filter (DBPF) based on a parallel-planar architecture where resonators are formed on the opposite sides of each substrate. The proposed architecture enables dual-band operation without an appreciable change in the volume of the DBPF and yields design freedom for the resonant frequencies by adjusting the distance between the substrates. A 2.4-/2.9-GHz band DBPF is fabricated using YBCO film deposited on a MgO substrate with a coplanar waveguide structure to investigate experimentally dual-band operation. The measurement results agree with those of the simulation.
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    Waveguide
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    Waveguide bandpass filters with improved stopband performance are investigated. The predicted filters performance show improved stopband performance and reduced filter dimensions compared with conventional E-plane bandpass filters. The validity of the method is confirmed by the measurement of a fabricated five resonator ridged waveguide bandpass filter, for which measured response shows good agreement with simulated results.
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    Transition band
    Electronic filter topology
    Waveguide filter
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    The construction principle of modified hairpin bandpass filters in microwave ranges is designed. It is shown, that amplitude-frequency characteristics of the proposed filters have more high steepness decline and best suppression in band of the barrier in comparison with its prototype. These filters are easy in fabrication and adjustment.
    Distributed element filter
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    Passband
    Multi-band device
    Two forms of quasi-optical filters are discussed herein for use at millimeter-wave frequencies and possibly for far infrared frequencies. One form consists of metallic grids with intervening dielectric support material which forms a quasi-optical filter analogous to the inductively coupled waveguide bandpass filter. Because of dielectric losses, the relatively weak upper stopband, and the rapidly repeating passbands, this type of structure leaves much to be desired as a bandpass quasi-optical filter. However, when designed for wide bandwidth, it makes a very good pseudo-high-pass filter. For moderate- to wide-band bandpass applications, pseudo-high-pass filters of this type can be designed to match with a form of quasi-optical low-pass filter previously treated by the authors, in order to give a bandpass filter with strong, broad stopbands on both sides of the passband. Design principles, computed performance, and experimental results are presented for both pseudo-high-pass and bandpass structures.
    Passband
    Stopband
    Electronic filter topology
    Waveguide filter
    Butterworth filter
    Citations (2)