Improved method of reactive loading for miniaturisation of transmission lines with minimal degradation in performance

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163918/1/mia2bf01667.pd

A comprehensive survey on 'circular polarized antennas' for existing and emerging wireless communication technologies

Circular polarized (CP) antennas are well suited for long-distance transmission attainment. In order to be adaptable for beyond 5G communication, a detailed and systematic investigation of their important conventional features is required for expected enhancements. The existing designs employing millimeter wave, microwave, and ultra-wideband (UWB) frequencies form the elementary platform for future studies. The 3.4-3.8 GHz frequency band has been identified as a worthy candidate for 5G communications because of spectrum availability. This band comes under UWB frequencies (3.1-10.6 GHz). In this survey, a review of CP antennas in the selected areas to improve the understanding of early-stage researchers specially experienced antenna designers has presented for the first time as best of our knowledge. Design implementations involving size, axial ratio, efficiency, and gain improvements are covered in detail. Besides that, various design approaches to realize CP antennas including (a) printed CP antennas based on parasitic or slotted elements, (b) dielectric resonator CP antennas, (c) reconfigurable CP antennas, (d) substrate integrated waveguide CP antennas, (e) fractal CP antennas, (f) hybrid techniques CP antennas, and (g) 3D printing CP antennas with single and multiple feeding structures have investigated and analyzed. The aim of this work is to provide necessary guidance for the selection of CP antenna geometries in terms of the required dimensions, available bandwidth, gain, and useful materials for the integration and realization in future communication systems

Design of multi-port network utilizing microstrip-slot technique for ultra wideband system

Nowadays, there is a lot of interest on the research and development related to ultrawideband system due to the increasing demands on the applications with low power, low cost and low interference. Thus, to cope with these demands, various researches are required for the development of front-end microwave components, which include six-port network as an alternative to a mixer-based design. The configuration of a six-port network is constructed by combining coupler and power divider. In the interest to have a simple design and convenient usage to form the sixport network with ultra wideband (UWB) operation, new power divider and coupler are designed by using microstrip-slot technique. All the proposed designs are simulated via the use of CST Microwave Studio 2010 and realized using Rogers TMM4 with a conductor coating of 35 μm, thickness of 0.508 mm and dielectric constant of 4.5. The developed prototypes of the proposed designs are verified by measurement using a vector network analyser (VNA). In this thesis, a design of twosection power divideris proposed with a great UWB performance of -3.8 dB ± 0.5 dB transmission coefficient and 0º ± 2º phase difference. This power divider has bandwidth improvement of 11.9% and size reduction of 23.33% compared to the conventional design. Meanwhile, for the coupler design, a UWB coupled-line coupler with zig-zag-shaped slot that has 3 dB ± 2 dB coupling coefficient and -90º ± 5º phase difference is proposed. The proposed coupler has 109.5% bandwidth improvement with the length reduction of 20% compared to the conventional coupler. The proposed UWB coupler is then implemented into a new proposed structure of UWB 90º power divider. Then, three configurations of six-port networks formed by UWB coupler, two-section power divider and 90º power divider are designed; which are named as Type I, Type II and Type III. From the observation, Type III demonstrates the best UWB performance with magnitude imbalance of ± 5 dB and phase imbalance of ± 10° that achieving the specified UWB design goal. Furthermore, Type III has the respective size reduction of 57.16% and 34.67% compared to Type I and II. In addition, by comparing to the previous works, the proposed design has broadest bandwidth of 100% and smallest size of 50.92 mm x 35 mm. Hence, the proposed six-port network has very well UWB performance with relatively compact size and simple design, which is easy to be fabricated

Lowpass Filter with Hilbert Curve Ring and Sierpinski Carpet DGS

Good performance and compact size are the paramaters which are vital when desiging a filter. One of the creteria of good performance is selectivity. This research, conducted by Hilbert Curve Ring and Siepinski Carpet, is used as defected ground structure to overcome filter selectivity. By using three cascadeds Hilbert Curve Ring defected ground structure cells and three steps Sierpinski carpet, a lowpass filter is designed and fabricated. The measurement result for lowpass filterwith Hilbert Curve Ring defected ground structure has sharper selectivity with the cut off frequency at 2.173 GHz and the insertion loss value is 2.135 dB. While the measurement result for three steps Sierpinski carpet has the cut off frequency at 1.728 GHz and the insertion loss value is 0.682 dB

Конструкции микрополосковых делителей мощности с уменьшенными размерами: монография

Данная книга посвящена исследованиям, связанным с процессом миниатюризации делителей мощности. В работе приведено сравнительное описание компактных делителей мощности, таких как делитель мощности Уилкинсона, направленный ответвитель на связанных линиях, шлейфный квадратурный делитель, гибридное кольцо и кроссовер. Каждая из этих конструкций была проанализирована для определения степени миниатюризации, рабочей частоты и полосы частот, а также параметров используемых подложек. В ходе исследования было рассмотрено более 150 оригинальных конструкций компактных делителей мощности

Compact Circularly Polarized Multiband Antennas for RFID Applications

This paper presents multiband circularly polarized (CP) antennas for radio frequency identification (RFID). A coax-fed and a microstrip-line-fed antennas having optimized cross-slots in their patches are first designed for dual-band CP operation. The microstrip-line-fed design is then modified, by incorporating a U-shaped slot in its partial ground plane, to achieve additional operation band with a CP characteristic. Simulation and measured results of the presented designs are reported. The measured results are in accordance with the computed ones. The compact size and CP property make these designs suitable for RFID applications

Defected Ground Structure: Fundamentals, Analysis, and Applications in Modern Wireless Trends

Slots or defects integrated on the ground plane of microwave planar circuits are referred to as Defected Ground Structure. DGS is adopted as an emerging technique for improving the various parameters of microwave circuits, that is, narrow bandwidth, cross-polarization, low gain, and so forth. This paper presents an introduction and evolution of DGS and how DGS is different from former technologies: PBG and EBG. A basic concept behind the DGS technology and several theoretical techniques for analysing the Defected Ground Structure are discussed. Several applications of DGS in the field of filters, planar waveguides, amplifiers, and antennas are presented

A Design of Branch-Line Coupler with Harmonic Suppression and Size Reduction Using Closed-Loop and Open-Loop Resonators

In this paper, a branch-line coupler using closed-loop and open-loop resonators with the operating frequency of 2.69 GHz is proposed. The designed microstrip circuit not only is able to suppress the second and the third unwanted harmonics but also reduces the occupied area to 59% of the traditional branch-line coupler. To explain how the employed resonators can suppress spurious frequencies, transmission zeros of both resonators based on their equivalent LC has been calculated, separately. To prove the abilities of the proposed branch-line coupler, the designed circuit has been fabricated and tested resulting in a good agreement between the measurement and simulation results. According to the S11 when it is less than -15 dB the bandwidth of the designed branch-line coupler is about 500 MHz, from 2.42 to 2.92 GHz .The comparison between the results of simulation and measurement are in good agreement

Antennas and Propagation Aspects for Emerging Wireless Communication Technologies

The increasing demand for high data rate applications and the delivery of zero-latency multimedia content drives technological evolutions towards the design and implementation of next-generation broadband wireless networks. In this context, various novel technologies have been introduced, such as millimeter wave (mmWave) transmission, massive multiple input multiple output (MIMO) systems, and non-orthogonal multiple access (NOMA) schemes in order to support the vision of fifth generation (5G) wireless cellular networks. The introduction of these technologies, however, is inextricably connected with a holistic redesign of the current transceiver structures, as well as the network architecture reconfiguration. To this end, ultra-dense network deployment along with distributed massive MIMO technologies and intermediate relay nodes have been proposed, among others, in order to ensure an improved quality of services to all mobile users. In the same framework, the design and evaluation of novel antenna configurations able to support wideband applications is of utmost importance for 5G context support. Furthermore, in order to design reliable 5G systems, the channel characterization in these frequencies and in the complex propagation environments cannot be ignored because it plays a significant role. In this Special Issue, fourteen papers are published, covering various aspects of novel antenna designs for broadband applications, propagation models at mmWave bands, the deployment of NOMA techniques, radio network planning for 5G networks, and multi-beam antenna technologies for 5G wireless communications