A compact quint-band bandpass filter based on stub-loaded resonators

This paper presents a planar quant-band bandpass filter with a high out-of-band rejection. The filter is based on inter-coupled stub-loaded resonators, where pairs of resonators are electromagnetically coupled to each other and the feed lines. This results in excitation of passbands, where the first and the third passbands are generated by λ/4 stub-loaded resonators. The second and the fifth passbands are excited by λ/2 stub-loaded resonators. And the fourth passband is generated by λ/2 resonators. The proposed technique provides sufficient degree of freedom to control the center frequency and bandwidth of the five passbands. In addition, the seven transmission zeros created around the passbands results in a quant-band filter with high selectivity, sharp 3dB cut-off frequency, high isolation, and low passband insertion-loss. Design methodology and simulation results of the filter are provided

Design and Analysis of a Wide Stopband Microstrip Dual-band Bandpass Filter

A novel configuration of a dual-band bandpass filter (BPF) working as a harmonic attenuator is introduced and fabricated. The proposed filter operates at 3 GHz, for UHF and SHF applications, and 6.3 GHz, for wireless applications. The presented layout has a symmetric structure, which consists of coupled resonators. The designing of the proposed resonator is performed by introducing a new LC equivalent model of coupled lines. To verify the LC model of the coupled lines, the lumped elements are calculated. The introduced filter has a wide stopband up to 85 GHz with 28th harmonic suppression, for the first channel, and 13th harmonic suppression, for the second channel. The harmonics are attenuated using a novel structure. Also, the proposed BPF has a compact size of 0.056 λg2. Having several transmission zeros (TZs) that improve the performance of the presented BPF is another feature. The proposed dual-band BPF is fabricated and measured to verify the design method, where the measurement results confirm the simulations

Microstrip diplexer for recent wireless communities

The diplexer is a dual-filter circuit with three ports that may share an antenna across two different frequency channels. As long as each band can be employed for sending and receiving signals, this technology can be used for multiple transmitters running on various frequencies. This paper will first present an overview of the diplexer concept, its importance in wireless networks, and its difference with duplexers. Then, the microstrip transmission line and its variation are discussed, as the filters and diplexers are designed using transmission lines. Typical electrical specifications are presented with measurement methods as well

UWB Technology

Ultra Wide Band (UWB) technology has attracted increasing interest and there is a growing demand for UWB for several applications and scenarios. The unlicensed use of the UWB spectrum has been regulated by the Federal Communications Commission (FCC) since the early 2000s. The main concern in designing UWB circuits is to consider the assigned bandwidth and the low power permitted for transmission. This makes UWB circuit design a challenging mission in today's community. Various circuit designs and system implementations are published in this book to give the reader a glimpse of the state-of-the-art examples in this field. The book starts at the circuit level design of major UWB elements such as filters, antennas, and amplifiers; and ends with the complete system implementation using such modules

A Review on the Structure, Application and Performance of the Passive Microstrip Devices

Microstrip technology is widely applied for design and implementation of several communication devices such as filters, diplexers, triplexers, multiplexers, couplers, etc. They are utilized to isolate desired signals and remove disturbing signals. The layout of filters, diplexers and triplexers have two, three and four ports, respectively. Passive filters have at least one pass channel, whereas diplexers have at least two channels to transmit the desired signal, and multiplexers have more passbands with more channels. In order to implement the passive components, first a cell called resonator must be designed. Creativity is very important in resonator design. It must be small and novel to get a better device than previous works. Therefore, the layout of previous reported resonator, used in passive microstrip devices, are studied in this work. There is a fierce competition among designers to miniaturize and increase the device performance. Hence we will investigate them, from the point of view size and performance, in this work. Some diplexers are multi-channel, which are more difficult to design than two-channel diplexers. Therefore, the multi-channel diplexers are less reported than the two-channel diplexers. The design of multiplexers is also very difficult because several channels must be controlled. Hence, they are less designed than filters and diplexers. The diplexers can be bandpass-bandpass or lowpass-bandpass, where the latest is less designed. This is because designing a lowpass-bandpass diplexer needs lowpass and bandpass resonators, whereas the design of a bandpass-bandpass diplexer needs only a bandpass resonator

Design-of-Experiment Based Systematic Tuning of Square Open Loop Resonator

Stub-loaded, square open loop resonator (SOLR) is a type of bandpass filter with dual-band response. It is believed that its center frequency values are determined by entire length of open loop resonator’s and open stub's lengths, the bandwidth values are determined by coupling between two resonators. However, design of experiments (DOE) method applied in this paper shows that the center frequency values are also affected by interaction between resonator length, stub length, and distance between the two resonators in pair. The DOE also shows that bandwidth values, both upper and lower bands, are not only affected by the distance between resonators but also by the resonator’s and stub’s lengths. Utilizing slope values of the significant factors, systematic tuning to SOLR can be done. With few steps, small error on frequency responses can be obtained

A Compact Reconfigurable Multi-mode Resonator-based Multi-band Band Pass Filter for Intelligent Transportation Systems Applications

A compact wide band reconfigurable bandpass filter (BPF) which utilises a hemi-circular flower shaped multimode resonator (MMR) is presented. The proposed MMR provides three resonant modes which fall within the broad frequency spectra. Among these, two modes are even and one is odd. These modes are optimised by varying the dimensions so as to obtain the desired frequency response. The fractional bandwidth is more than 96 per cent. The filter can be operated as multi-band BPF. In OFF condition of ‘Pin’ diode, the centre frequencies are 2.43 GHz, 3.5 GHz, and 5.9 GHz in ON condition of ‘Pin’ diode centre frequencies are 2.43 GHz, 3.5 GHz, 5.9 GHz, 6.5 GHz, and 8.8 GHz which are used for vehicular, WiMAX, intelligent transportation systems and satellite communication respectively. Microstrip filter structures are integrated with ‘Pin’ diodes. Appropriate biasing has been provided by choosing lumped components with precise values. The insertion loss in OFF condition are 0.5 dB, 0.67 dB, and 0.8 dB and in ON condition 0.5 dB, 0.7 dB, 1.2 dB, and 1.9 dB. The measured results agree well with the full-wave simulated results

High-Performance Ultra-Compact Dual-Band Bandpass Filter for Global System for Mobile Communication-850/Global System for Mobile Communication-1900 Applications

This work presents a novel microstrip dual-band bandpass filter (BPF) using meandros spirals and patch cells, which is proposed for the first time by this work. It occupies a very compact size of 0.0017 λg2. The proposed filter is designed to operate at Fo1=0.85 GHz and Fo2=1.85 GHz for GSM-850/GSM-1900 applications. In addition to the small size, it has several advantages in terms of wide fractional bandwidths (FBW), low insertion losses and high return losses at both channels. The simulated insertion losses at the lower and upper passbands are 0.05 dB and 0.1 dB, respectively. Another advantage of the proposed BPF of this work is the attenuated harmonics, where it is able to suppress 1st, 2nd, 3rd and 4th harmonics (4.11 Fo1) with -20 dB maximum harmonic level

A Survey of Differential-Fed Microstrip Bandpass Filters: Recent Techniques and Challenges

Differentially driven devices represent a highly promising research field for radio frequency (RF), microwave (MW), and millimeter-wave (mmWave) designers and engineers. Designs employing differential signals are essential elements in low-noise fourth-generation (4G) and fifth-generation (5G) communications. Apart from the conventional planar MW components, differential–fed balanced microstrip filters, as promising alternatives, have several advantages, including high common-mode rejection, low unwanted radiation levels, high noise immunity, and wideband harmonic suppression. In this paper, a comprehensive and in-depth review of the existing research on differential-fed microstrip filter designs are presented and discussed with a focus on recent advances in this research and the challenges facing the researchers. A comparison between different design techniques is presented and discussed in detail to provide the researchers with the advantages and disadvantages of each technique that could be of interest to a specific application. Challenges and future developments of balanced microstrip bandpass filters (BPFs) are also presented in this paper. Balanced filters surveyed include recent single-, dual-, tri-, and wide-band BPFs, which employ different design techniques and accomplish different performances for current and future wireless applications

Design, Modelling and Implementation of Several Multi-Standard High Performance Single-Wideband and Multi-Wideband Microwave Planar Filters

The objectives of this work are to review, investigate and model the microwave planar filters of the modern wireless communication system. The recent main stream of microwave filters are classified and discussed separately. Various microwave filters with detailed applications are investigated in terms of their geometrical structures and operational performances. A comprehensive theoretical study of microwave filters is presented. The main types of microwave filters including the basic low-pass filters such as Butterworth and Chebyshev filters are fully analysed and described in detail. The transformation from low-pass prototype filters to high-pass filters, band-pass filters and band-stop filters are illustrated and introduced. Research work on stepped impedance resonator (SIR) and asymmetric stepped impedance resonator (ASIR) structure is presented. The characteristics of λg/4, λg/2 and λg (λg is the guided wavelength of the fundamental frequency in the free space) type SIR resonators, and the characteristic of asymmetric SIR resonator are categorized and investigated. Based on the content mentioned above, novel multi-standard high performance asymmetric stepped impedance resonator single-wideband and dual-wideband filters with wide stopbands are proposed. The methodologies to realize wide passband and wide stop-band filters are detailed. In addition, multi-standard high performance triplewideband, quadruple-wideband and quint-wideband filters are suggested and studied. The measurement results for all prototype filters agree well with the theoretical predictions and simulated results from Ansoft HFSS software. The featured broad bandwidths over single/multiple applicable frequency bands and the high performances of the proposed filters make them very promising for applications in future multistandard wireless communication