Novel compact ultra-wideband (UWB) bandpass filters (BPFs) with single or multiple notch-bands to avoid interference from existing radio systems are presented. A compact UWB BPF is proposed and designed based on broadside-coupled stepped impedance resonators (SIRs) at first, and then notch-bands are generated by embedding open-circuit stubs into broadside-coupled SIRs. Because of the harmonic suppression behaviour of SIRs, the proposed UWB BPFs have a wide stopband and high rejection level. The characteristic of the proposed notch-structure was investigated by full-wave simulations. Multilayer liquid crystal polymer (LCP) technology was used to implement the designed UWB BPFs. In the experiments, a UWB BPF with excellent stopband performance was designed to meet the Federal communications commission-defined indoor limits at first, and then UWB BPFs with single, double and triple notch-bands were designed to demonstrate the flexible notch-band, high-selectivity and wideband harmonic suppression performances of the proposed filter. The designed BPFs were fabricated by a multilayer LCP lamination process and measured using a vector network analyser. Good agreement between the predicted and measured results was obtained as presented here.
In this study, a novel substrate integrated folded‐waveguide resonator filter is presented and an aperture coupling between adjacent resonators is introduced, which is characterized using full‐wave EM simulations and verified experimentally. A demonstrator of two‐pole substrate integrated folded‐waveguide resonator filter of this type has been designed, fabricated, and tested. As an example, a two‐pole BPF centered at 4.675 GHz with a fractional bandwidth of 7.4% is designed, fabricated, and measured. Simulations and experimental results are presented to validate the design and to show the advantages of this type of filter. The simulated and measured results show an excellent agreement. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1111–1114, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23272
This paper presents a primary investigation into developing a compact dual passband filter using novel foldedwaveguide resonators with a multilayer structure. A new coupling scheme for dual-band operation is realized. Both slot and aperture couplings are used for the implementation. For the demonstration, a 4-pole dual-band filter of this type has been designed, fabricated and tested. Simulation and experimental results are presented to validate the design and to show the advantages of this type of filter.Index Terms -Folded-waveguide resonators, microwave filters, dual passband filter. I. I. INTRODUCTIONecent development in wireless communication and radar systems has presented new challenges to design and produce high-quality miniature components with a dualband operation. Advances in wireless systems have created a need for dual-band operation for microwave filters. Bandpass filters are important components of wireless systems as they enable band selection in RF transceivers, separating the different receiver functions of interest and isolating a specific band from interferers in dense wireless traffic. As wireless systems converge into common devices, it will be increasingly important to have miniaturized filters that can select more than one band at a time. One fabrication technology that has been demonstrated to be suitable for extremely compact filtering is low-temperature co-fired ceramic (LTCC) [1, 2]. Synthesis method of a self-equalized dual-passband filter has also been presented [3]. The coupling between two modified open-loop resonators is used to create a dual-band filter in microstrip technology [4]. Polynomial approaches and coupling matrices are applied to the design of dual-band bandpass [5] and bandstop filters [6] in waveguide technology. Other forms of dual-band bandpass filters have also reported in [7][8][9].In this paper, a new design of 4-pole dual passband filter using double layer of slotted folded-waveguide (FWG) resonators is presented. The 4-pole dual passband filter design is based on a new coupling scheme and implemented with a compact multilayer structure. The design has been verified with the EM simulation and the experiment. II. DUAL-BAND FILTER STRUCTUREThe proposed FWG dual-band filter is illustrated in Fig.1. It is notable that there are two inserted metal plates having a slot with the length SL. Each of the metal plates has a thickness of t and the upper and lower air-filled half cavities have a depth of h/2 to form a so-called slotted FWG cavity. Owing to the new slot introduced, a pair of resonant modes, which have the same resonant frequency, can be excited within each slotted FWG cavity. Thus, a single slotted FWG cavity, which has the same size as that of a conventional quarter-wavelength FWG resonator [10], can be used as a double-tuned resonator circuit, resulting in a significant size reduction for the development of new compact filters. The proposed filter has a multilayer structure, which allows the couplings between adjacent slotted FWG cavities to be introduced ...
This paper proposes a novel ultra wideband (UWB) bandpass filter using multilayer quasi-lumped structure on organic liquid crystal polymer (LCP) substrate. In this study, broadside coupled square patches and high impedance microstrip lines are adopted as quasi-lumped elements for realizing proposed filter. A 7-pole ultra wideband bandpass prototype is designed based on lump-element bandpass filter and verified by full-wave simulation. The designed BPF is fabricated using multilayer organic liquid crystal polymer (LCP) process and measured using vector network analyzer. Good agreement between simulated and measured responses is observed. The measurement results show that the fabricated filter has a fractional bandwidth of 118.75% and low insertion loss of 0.25 dB at centre frequency 6.4 GHz. The measured filter has wide stopband and excellent rejection level higher than 31.7 dB from 11.5 GHz to 17.20 GHz.
The growth of mobile traffic volume has been exploded because of the rapid improvement of mobile devices and their applications. Heterogeneous networks (HetNets) can be an attractive solution in order to adopt the exponential growth of wireless data. Femtocell networks are accommodated within the concept of HetNets. The implementation of femtocell networks has been considered as an innovative approach that can improve the network’s capacity. However, dense implementation and installation of femtocells would introduce interference, which reduces the network’s performance. Interference occurs when two adjacent femtocells are operated with the same radio resources. In this work, a scheme, which comprises two stages, is proposed. The first step is to distribute radio resources among femtocells, where each femtocell can identify the source of the interference. A constructed table is generated in order to measure the level of interference for each femtocell. Accordingly, the level of interference for each sub-channel can be recognized by all femtocells. The second stage includes a mechanism that helps femtocell base stations adjust their transmission power autonomously to alleviate the interference. It enforces a cost function, which should be realized by each femtocell. The cost function is calculated based on the production of undesirable interference impact, which is introduced by each femtocell. Hence, the transmission power is adjusted autonomously, where undesirable interference can be monitored and alleviated. The proposed scheme is evaluated through a MATLAB simulation and compared with other approaches. The simulation results show an improvement in the network’s capacity. Furthermore, the unfavorable impact of the interference can be managed and alleviated.
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