A miniaturized fractal based hexagonal open-loop resonator BPF for WiMAX applications

Improvement of out-of-band characteristics for a bandpass filter (BPF) using /spl lambda//2 microstrip line (MSL) resonators is carried out. The basic operations of a tapped /spl lambda//2 resonator are examined theoretically and experimentally. The application to MSL resonator BPF with improved spurious responses are also examined. An extended 2-pole BPF with improved skirt characteristics and target spurious response is proposed and realized. It is confirmed that the present concept is great useful for improving out-of-band characteristics of the /spl lambda//2 resonator BPFs.

A miniaturized bandpass filter (BPF) using defected ground structure (DGS) resonator with the characteristic of harmonic rejection is developed in this paper. The second and third harmonics of the proposed BPF are rejected by the characteristic of stepped-impedance DGS resonator. Moreover, open stubs are established so that two adjustable transmission zeros can independently be created to extend the stopband and improve the rejection level. Finally, a second-order BPF, centered at 1.62 GHz with a stopband extended up to 5.6 GHz and a rejection level better than 20 dB, is designed and implemented for GPS application. A good agreement between simulation and measurement verifies the validity of this design methodology.

Planar microwave bandpass filters (BPFs) are an essential component in many communication systems. Traditional BPF design focuses on the application of frequency-invariant K-/J-inverters inserted between the two resonant modes or served as the external coupling to feed the resonators. This design method is most suitable for narrow bandwidth BPFs, but for wideband cases it is difficult for a direct application. To solve this problem, a synthesis method based on a modified general Chebyshev function and the Richard’s transformation has been proposed to characterize the frequency response over the whole frequency range for the wideband BPF designs. As for the corresponding circuit structure, short-circuited stepped-impedance multi-mode resonators (MMRs) serve as the foundation to the designs in this dissertation. By parallel-connecting or folding the MMRs, a class of dual-wideband BPFs has been developed. Based on the above discussion, this dissertation presents the wideband BPF designs in two aspects, the proposed filter synthesis procedure and a new class of circuit structures to realize the target filtering responses. As the foundation of this research work, short-circuited MMRs have been researched in the first place for a single-wideband BPF design. n sections of cascaded commensurate lines are used to group the resonances, and short-ended stubs are shunt on its two sides to inductively feed the MMR. For the filter design, a Chebyshev filtering function is used to characterize the frequency response of the circuit. By equating the filtering function to the transfer function of the circuit, the design parameters are obtained. The first set of dual-wideband BPFs is formed by parallel-connecting two dissimilar single-wideband BPFs, both formed by stepped-impedance MMRs. The two transmitting paths of 180o phase difference are used to generate up to two pairs of transmission zeroes (TZs) with symmetry to the dual-wide passbands. By appropriately choosing the characteristic impedances of the two paralleled MMRs, one pair of TZs is located in real frequencies contributing to the attenuation between the two passbands, whereas the second pair of TZs is located in imaginary frequencies adjusting the group delay within the passbands. The short-circuited stubs, in shunt connection on the two sides of the MMR, act as the inductive loading element to feed the MMR and to flatten the passband. In the meanwhile, they introduce TZs at multiple of π to suppress the DC-component. Following a similar design principle, the second set of dual-wideband BPF has been proposed as an improved design in terms of realizing a more compact size, the greater flexibility in terms of reflection zeros in the passband and an extra degree of freedom in choosing characteristic impedances. The generic structure of the proposed filters is formed by folding a MMR along its symmetrical plane and by coupling a pair of short-circuited stubs on the two ends of the MMR. Thus, two signal transmitting paths, one from the folded MMR and another from the loaded stubs, are used to generate additional TZs between the two passbands. By increasing sections of the loaded MMR, the reflection zeros in the passband is enlarged. Under fully-coupled structure, the merit of compact size and extra design freedom is obtained. For these two sets of dual-wideband BPFs mentioned above, the even-/odd-mode analysis method has been used to derive the transfer function to characterize their frequency responses. Given the properties of the proposed filters, the commonly used generalized Chebyshev filtering function as well as its transferred dual-band function is not appropriately used herein. Instead, a generalized Chebyshev filtering function, originally developed for a single-wideband BPF design, is readily applied. By directly formulating a filtering function with mirror to the origin, it has dual passbands respectively located at positive and negative frequency ranges. To accurately account for the wideband response, a TZ is assigned at the origin. Next, the Richard’s transformation is applied to transfer the normalized frequency response to its dual-band counterpart. With this proposed synthesis procedure, the targeted filtering function is characterized by a ratio of two polynomials. By equating these two aforementioned functions, which are the ideal filtering function from the specifications and the transfer function from the circuits, all the circuit design parameters are obtained. Finally, the proposed single-/dual-wideband bandpass filters have been synthesized and designed for practical implementation. The experimental results of the fabricated filter circuits have strongly verified these new filter structures and their corresponding synthesis method proposed.

Characterizing the energy cost of different physical (PHY) layer building blocks is becoming increasingly important in modern cellular-based communications, considering the cross sector requirements for performance enhancements and energy savings. This paper presents energy profiling metrics of different PHY-layer FPGA implementations encountered in modern wireless communication systems. The results give an insight of the distribution of the consumed energy in different baseband building blocks or configurations before and after applying power optimizations in the FPGA design and implementation.

Modulation is an indispensable component in modern communication systems and multiple phase shift keying (MPSK) is widely studied to improve the spectral efficiency. It is of great significance to study the MPSK modulations of symmetric phases in practice. Based on convolutional neural networks (CNNs), we propose a generic architecture for MPSK demodulation, referred to as CNN-MPSK. The architecture utilizes a single-layer CNN and a pooling trick to crop network parameters. In comparison with conventional coherent demodulation, the CNN-MPSK eliminates three modules, i.e., carrier multiplication, bandpass filter and sampling decision. Thus, we can avoid π-inverted phenomenon from the multiplication of two carrier waves with different phases, as the carrier multiplication is not employed. In addition, we can reduce errors introduced by sampling decision. Furthermore, we conduct bit-error-rate tests for binary-PSK, 4PSK, 8PSK, and 16PSK demodulation. Experimental results reveal that the performance of CNN-MPSK is almost the same to that of conventional coherent demodulation. However, the CNN-MPSK demodulation reduces computational complexity from O(n2) to O(n) as compared to the latter one. Additionally, the proposed scheme can be readily applied for demodulation of non-symmetric MPSK constellations that maybe distorted by linear and nonlinear impairments in communication systems.

This paper presents a miniaturized square patch resonator with two different pairs of etched slots for bandpass filter applications. The slots split the fundamental degenerate modes of the resonator and allow the control of both central frequency and bandwidth, providing filter design flexibility. A two- and a four-pole filter centered at 2.4 GHz were designed using the same resonator and fabricated. Experimental results of the two-pole filter showed a bandwidth of 14%, return loss better than 18 dB, and minimum insertion loss of 0.6 dB. This filter exhibited a size reduction of 49% compared to an unperturbed square patch resonator at the same frequency. The four-pole filter results showed a bandwidth of 9.8%, and 33 dB rejection at the second harmonic band.

Solving channel equalization problem in communication systems is based on adaptive ltering algorithms. Today,Mobile Agents (MAs) with Recurrent Neural Networks (RNNs) can be also adopted for e ective interferencereduction in modern wireless communication systems (WCSs). In this paper MAs with RNNs are proposed asnovel computing algorithms for reducing interferences in WCSs performing an adaptive channel equalization.The method to provide it is so called MAs-RNNs. We perform the implementation of this new paradigm forinterferences reduction. Simulations results and evaluations demonstrates the e ectiveness of this approach andas better transmission performance in wireless communication network can be achieved by using the MAs-RNNsbased adaptive ltering algorithm.Keywords: Wireless communication systems, Mobile Agents, Recurrent Neural Networks, interferences reduc-tion, channel equalization 1. INTRODUCTION New challenges in modern communication is to conceive highly reliable and fast communication system deprivedfrom problems caused by multipath fading in wireless channels. A very important problem in data commu-nications is channel equalization. i.e., the removal of interferences introduced by linear or nonlinear messagecorrupting mechanisms. Thus the originally transmitted symbols can be recovered correctly at the receiver.New techniques to provide the optimal detection under bad channel estimation and solving the channel equal-ization must be developed and evaluated. To achieve fast and reliable wireless digital communication, as forinter-symbol interference (ISI), studies must concern adaptive equalization to minimize the communication errors

In this paper, a band-pass filter with dual-band is designed using the slotted ring resonator technique along with the coupling lines technique. The design is intended for use with satellite applications to cover the frequencies at 1.4 GHz and GHz and 4.5 GHz. The substrate used in this design is FR-4 with relative permittivity of 3.65 and 1.6 mm thickness. Measurement results of the fabricated samples are in good agreement with the simulated results.

Pass Band Filter with precise selectivity is one of the major requirements of MMIC circuits. The major challenge while designing is size. This paper presents a size reduction technique for the Pass Band Filter by implementing SIW (Substrate Integrated Waveguide). The simulated results for the based filter show size reduction as resonance is shifting at the lower side of the frequency range. The passband filter without SIW is having resonance at 8.4GHz with return loss -26dB. After Implementing SIW results show resonance frequency at 7.2 GHz with a return loss of -23.86 dB without affecting the selectivity of the pass band filter. For Design Simulation, Ansys HFSS is used.

A wideband technique based on the modification of parallel-coupled line microstrip bandpass filter (BPF) is presented in this paper. The wideband response can be obtained by using a half-wavelength transmission line (TL) connected between the two cascaded of quarter-wavelength parallel-coupled lines. Since a conventional half-wavelength TL can be formed by a quarter-wavelength parallel-coupled line resonator with a three-line conductor, a BPF with compact circuit size and symmetrical structure can be achieved. By applying a T-shaped TL in the cascaded configuration, the wideband BPF not only give more overall compact filter's size but also further suppress the first spurious response. The prototype of cascaded BPF is designed with the center frequency of 2 GHz and fabricated on an FR-4 substrate in the microstrip structure. Good agreement between the simulated and measured results is obtained.

The front-end is a crucial component in modern wireless communication systems. For SISO systems minimizing the front-end noise factor is optimal, and this also applies to MIMO systems with i.i.d. noise. However, for compact MIMO receivers that may exhibit spatially correlated noise, e.g., through antenna mutual coupling, the optimal design procedure is not clear. In this paper we develop MIMO low-noise design principles from a communication theory perspective by deriving generalizations of SNR and noise factor from various MIMO communication schemes. As one result, we are able to derive optimal matching networks for a bank of uncoupled amplifiers.

This paper presents a design approach for a /spl lambda//2 resonator bandpass filter by using the artificial neural network (ANN) modeling technique. Three important dimensions of the filter layout are used to capture critical input-output relationships in the ANN model. Once fully developed, the ANN model has been shown to be as accurate as an EM simulator and much more efficient computationally in the design optimization of the filter.

In this paper, novel microstrip open‐loop resonator (OLR) bandpass filters are presented. By introducing additional spiral inductors as well as gap‐coupled capacitors, the bandpass filters (BPFs) exhibit another attenuation pole at the upper stopband. Also, a novel miniaturized high‐Q duplexer for Universal Mobile Telecommunications System (UMTS) bands using these BPFs is discussed. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 69–72, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20904

Ultra-wideband (UWB) bandpass filter with high selectivity response is contrived on the multimode characteristic of stepped-impedance resonators (SIRs). To achieve strong coupling requirement, two-layer broadside-coupled structure is employed. Using three triple-mode SIRs, quasi-Chebyshev filter with nine transmission poles is synthesized with a fractional bandwidth (BW) Delta = 110%. Measured results of experimental circuits show good agreement with simulated responses.

In this contribution, a Si-LDMOS transistor is used to design a power amplifier (PA) in a broad frequency band covering a number of modern wireless communications systems. The design, implementation, and experimental results of 4 W wideband Si-LDMOS PA are presented. A method based on source/load--pull characterization has been used to extract optimum source and load impedances over the desired bandwidth. Following this, a systematic approach to design wideband matching network is suggested. In the frequency band 1.7-2.7 GHz, 3.4 - 4.0 W output power and 25 % drain efficiency were achieved. The 3rd-order intermodulation distortion (IMD3) performance of the designed PA is evaluated by providing a two-tone signal to the amplifier. At two-tone output power of 1 W, IMD3 of around -30 dBc was measured over the design band.