A design of compact ultra wideband coupler for butler matrix

A design of 3 dB compact ultra wideband (UWB) coupler for a 4 × 4 Butler Matrix, which is operating between 3 and 11 GHz frequency range, is presented in this paper. The proposed design uses multilayer technology that allows having a compact and broad bandwidth coupler. The design uses elliptically shaped broadside coupled strips and a slot created in a common ground plane of two dielectric substrates with the same shape. The design then being fabricated on 0.8 mm thick FR4 substrates and it occupies the dimension of 30 mm × 15 mm. The simulation and experimental results show a good performance in terms of bandwidth, which covers the entire UWB operation. In addition, detailed analysis of air gap effect for S-parameters and phase difference of the designed coupler is presented in this study

Mountain-Shaped Coupler for Ultra Wideband Applications

This paper demonstrates a novel mountain-shaped design for a compact 3-dB coupler operating at ultra-wideband (UWB) frequencies from 3.1GHz to 10.6 GHz. The proposed design was accomplished using multilayer technology in which the structure is formed by three layers of conductors interleaved by a layer of substrate between each conductor layer. Simulation was carried out using CST Microwave Studio; the result was then compared with results from rectangular and star-shaped couplers that implemented the same technique. The results obtained show that the proposed new coupler has better performance compared to both rectangular and star-shaped coupler designs in terms of return loss, isolation, and phase difference. The coupler was fabricated and measured; the measurement results satisfactorily agree with the simulation results

Millimeter-Wave Components and Antennas for Spatial and Polarization Diversity using PRGW Technology

The evolution of the wireless communication systems to the future generation is accompanied by a huge improvement in the system performance through providing a high data rate with low latency. These systems require access to millimeter wave (mmWave) bands, which offer several advantages such as physically smaller components and much wider bandwidthcomparedtomicrowavefrequencies. However, mmWavecomponentsstillneed a significant improvement to follow the rapid variations in future technologies. Although mmWave frequencies can carry more data, they are limited in terms of their penetration capabilities and their coverage range. Moreover, these frequencies avoid deploying traditional guiding technologies such as microstrip lines due to high radiation and material losses. Hence, utilizing new guiding structure techniques such as Printed Ridge Gap Waveguide (PRGW) is essential in future mmWave systems implementation. ThemainpurposeofthisthesisistodesignmmWavecomponents,antennasubsystems and utilize both in beam switching systems. The major mmWave components addressed in this thesis are hybrid coupler, crossover, and differential power divider where the host guidingstructureisthePRGW.Inaddition,variousdesignsfordifferentialfeedingPRGW antennas and antenna arrays are presented featuring wide bandwidth and high gain in mmWave band. Moreover, the integration of both the proposed components and the featured antennas is introduced. This can be considered as a significant step toward the requirements fulfillment of today's advanced communication systems enabling both space and polarization diversity. The proposed components are designed to meet the future ever-increasing consumer experience and technical requirements such as low loss, compact size, and low-cost fabrication. This directed the presented research to have a contribution into three major parts. The first part highlights the feeding structures, where mmWave PRGW directional couplers and differential feeding power divider are designed and validated. These components are among the most important passive elements of microwave circuits used in antennabeam-switchingnetworks. Different3-dBquadraturehybridcouplersandcrossover prototypes are proposed, featured with a compact size and a wide bandwidth beyond 10 % at 30 GHz. In the second part, a beam switching network implemented using hybrid couplers is presented. The proposed beam switching network is a 4 × 4 PRGW Butler matrix that used to feed a Magneto-electric (ME) dipole antenna array. As a result, a 2-D scanning antenna array with a compact size, wide bandwidth, and high radiation efficiency larger than84%isachieved. Furthergainenhancementof5dBiisachievedthroughdeployinga hybridgainenhancementtechniqueincludingAMCmushroomshapesaroundtheantenna array with a dielectric superstrate located in the broadside direction. The proposed scanning antenna array can be considered as a step toward the desired improvement in the data rate and coverage through enabling the space diversity for the communication link. The final activity is related to the development of high-gain wide-band mmWave antenna arrays for potential use in future mmWave applications. The first proposed configuration is a differential feeding circular polarized aperture antenna array implemented with PRGW technology. Differential feeding antenna designs offer more advantages than single- ended antennas for mmWave communications as they are easy to be integrated with differential mmWave monolithic ICs that have high common-mode rejection ratio providing an immunity of the environmental noise. The proposed differential feeding antenna array is designed and fabricated, which featured with a stable high gain and a high radiation efficiency over a wide bandwidth. Another proposed configuration is a dualpolarized ME-dipole PRGW antenna array for mmWave wireless communication. Dual polarizationisconsideredoneofthemostimportantantennasolutionsthatcansavecosts and space for modern communication systems. In addition, it is an effective strategy for multiple-input and multiple-output systems that can reduce the size of multiple antennas systems by utilizing extra orthogonal polarization. The proposed dual- polarized antenna array is designed to achieve a stable gain of 15 ± 1 dBi with low cross- polarization less than -30 dB over a wide frequency range of 20 % at 30 GHz

Design and Analysis of Wideband Nonuniform Branch Line Coupler and Its Application in a Wideband Butler Matrix

This paper presents a novel wideband nonuniform branch line coupler. An exponential impedance taper is inserted, at the series arms of the branch line coupler, to enhance the bandwidth. The behavior of the nonuniform coupler was mathematically analyzed, and its design of scattering matrix was derived. For a return loss better than 10 dB, it achieved 61.1% bandwidth centered at 9 GHz. Measured coupling magnitudes and phase exhibit good dispersive characteristic. For the 1 dB magnitude difference and phase error within 3∘, it achieved 22.2% bandwidth centered at 9 GHz. Furthermore, the novel branch line coupler was implemented for a wideband crossover. Crossover was constructed by cascading two wideband nonuniform branch line couplers. These components were employed to design a wideband Butler Matrix working at 9.4 GHz. The measurement results show that the reflection coefficient between the output ports is better than 18 dB across 8.0 GHz–9.6 GHz, and the overall phase error is less than 7∘

Design of Tunable Beamforming Networks Using Metallic Ridge Gap Waveguide Technology

Wireless communication is a leap of development in the history of humanity. For the past 100 years, a considerable effort has been spent to develop better standards, and technologies for a higher speed wireless communication with high system capacity for different applications. This requires the design of a high-frequency, point-to-multipoint antenna array system to achieve the mentioned goals. In addition, the reconfigurability of this antenna system is essential to change the system characteristics to achieve acceptable performance in different situations. The main goal of this thesis is to design a reconfigurable beamforming network to work on the Ka-band for waveguide applications. Among different beamforming networks in the literature, the Butler matrix is chosen due to its higher efficiency and the smaller number of components required than other beamforming networks. The Butler matrix is designed using a dual-plane topology to avoid using crossovers. Ridge gap waveguide technology is chosen among different transmission lines to implement the Butler matrix for several reasons: It does not need dielectrics to operate, so its power handling capacity is defined by the gap height, and it has no dielectric losses. Its zero-field region represents the operating principle for some tunable devices introduced here and its contactless nature, which eases the assembly of waveguide parts at the millimeter-wave frequencies. The reconfigurability of the Butler matrix is implemented such that beamwidth, maximum gain, and beam direction may be all tuned for optimum system performance. To that end, several components are designed to achieve the required target, and strict requirements are placed on several components to achieve an acceptable cascaded-system performance. These components include a ridge gap waveguide 90o-hybrid working over a more than 30% bandwidth, which can provide several coupling levels ranging from 3 dB to 33 dB and a return loss and isolation better than 30 dB. Another component is a wideband reconfigurable power splitter that has a 40% bandwidth, a return loss better than 20 dB in the worst case and the ability to achieve all power splitting ratios including switching between the two guides. In addition, a wideband reconfigurable phase shifter is designed to have 33% bandwidth and phase shift tuning range from 0o to 200o. Two coaxial-to-ridge gap waveguide transitions are designed to work over a more than 100% bandwidth to facilitate testing different ridge gap waveguide components. Analysis of the asymmetric double ridge waveguide is introduced where its impedance is deduced and may be used to design a single to double ridge waveguide transition useful for the dual-plane Butler matrix introduced here. In addition, this concept is used to develop a wideband unequal power divider in the single ridge waveguide technology. At the end, the whole system is assembled to show its performance in different tuning states. The ability of the system to produce radiation patterns of different characteristics is demonstrated. The presented Butler matrix design is a promising beamforming network for several applications like radar, base stations for mobile communications, and satellite applications

Ultra wideband butler matrix for beam-forming network

The need of having passive microwave devices that can operate in Ultra Wideband (UWB) frequency range has been arising these days due to their features that capable in bringing significant advances in wireless communications such as low power consumption, minimal interference and large channel capacity. However, the low power consumption has led to short range communication. Butler Matrix Beam Forming System is one of the solutions to solve such issue. Multilayer UWB couplers and multilayer UWB phase shifter are possible devices to develop a compact system design of Butler Matrix for UWB as the crossover function has been eliminated by this technique. New designs of multilayer UWB couplers and multilayer UWB phase shifters, which are used to construct the UWB Butler Matrix are introduced. These two main components are designed to function in the UWB frequency range to permit construction of the UWB Butler Matrix. In this research, the proposed UWB Butler Matrix achieves an improvement of 18.6% wider bandwidth compared to available UWB Butler Matrix and 31.1% size reduction compared to planar configurations of Butler Matrix. Simulation results are obtained by using Computer Simulation Technology Microwave Studio 2012. All measurements of S-parameters and phase differences performances are performed using a Vector Network Analyzer. Meanwhile, the measurements on beam directions of the UWB Butler Matrix are steered towards a particular direction by switching the input port accordingly. The switched beam antenna array system shows that four orthogonal beams are produced at four different directions. All measurements result show a very good agreement with the simulation result

Design and development of broadband gap waveguide-based 0-dB couplers for Ka-band applications

The design and fabrication of a wideband millimetre-wave 0-dB coupler is proposed in this paper using gap waveguide technology for low-loss and high-power applications in 30-GHz frequency band. To overcome the fabrication challenges in millimetre-wave frequencies, the gap waveguide technique is utilised. Two gap waveguide-based coaxial- and waveguide-fed 0-dB couplers are designed with broadband performance, high return loss, acceptable coupling flatness and high isolation. For verifying the performance of the proposed structures, a prototype of the waveguide-fed 0-dB coupler is manufactured and measured. The measurement results show that the return and insertion losses and the isolation of the fabricated 0-dB coupler is better than 18 dB, 0.5 and 18 dB, respectively, in the specified frequency range from 26.2 to 34 GHz. Moreover, the breakdown power level of the proposed millimetre-wave structures is in kW orders to satisfy the high-power requirements

Review of Switched Beamforming Networks for Scannable Antenna Application towards Fifth Generation (5G) Technology

The next generation wireless network (5G) addresses the evolution beyond mobile internet to massive Internet-of-Things (IoT) which will take off from 2019/2020 onwards. The essential design features in 5G wireless network system are massive multiple-input and multiple-output (MIMO) and steerable antenna array. The higher capacity, lower power transmission and larger system coverage offered by upcoming 5G technology can be realized using switched-beam antenna such as Butler matrix, Rotman lens, Blass matrix and Nolen matrix. Review of their design features and performance results will be compared in this article. Butler matrix can be the best approach owing to low complexity, orthogonal beams and less components utilization

Influence of the directional coupler’s parameters on the characteristics of Butler matrix 4×4

В работе получена математическая модель матрицы Батлера 4×4 без кроссоверов на основе 3 дБ 90° направленных ответвителей. Получены и исследованы зависимости распределения амплитуд и набега фазы сигналов на выходах, уровня согласования входов матрицы от характеристик направленного ответвителя, а именно: разбалансировки амплитуд и фаз сигналов на выходах плечей, уровней согласования и развязки ответвителя.Introduction. A brief description of the Butler matrix operating principle and structure is given. The purpose of the study is defined and justified. Mathematical model of Butler matrix. The overall scattering matrix of 4×4 Butler matrix without crossovers is obtained. A well-known method of multipoles cascade connection is used to derive the scattering matrix. 3 dB 90° symmetric and lossless directional couplers are used as building blocks for Butler matrix. The phase shift of phase shifters assumed as frequency-independent. Modeling of the directional coupler’s real characteristics. Four characteristics of directional coupler are considered as affecting the overall performance of Butler matrix: amplitude and phase imbalance at the output ports, reflection and isolation of input ports. Analysis of the results. The plots of amplitude distribution at the output ports and phase difference between adjacent output ports versus the characteristics of directional coupler are shown. The analysis of results is given. Maximum permissible parameters of directional coupler are determined to obtain a qualitative Butler matrix. Conclusions. General conclusions of the paper are given. Possible directions of further research are identified.В работе получена математическая модель матрицы Батлера 4×4 без кроссоверов на основе 3 дБ 90° направленных ответвителей. Получены и исследованы зависимости распределения амплитуд и набега фазы сигналов на выходах, уровня согласования входов матрицы от характеристик направленного ответвителя, а именно: разбалансировки амплитуд и фаз сигналов на выходах плечей, уровней согласования и развязки ответвителя