Design Of A Quasi-Lumped Element Resonator Antenna With Magnetic Coupling Feeding

Advancement in wireless systems and subsequent increasing demand in wireless mobility has enabled the invention of the wearable wireless systems. Realizing this fact, lightweight, conformable, unobtrusive, and ubiquitous equipment, which can be integrated into everyday use, are now crucial design considerations. These wireless communication systems contain several parts in which compact antennas are an essential subpart. However, many technical challenges arise in designing robust, compact and efficient antennas that deliver the necessary performance to support the emerging applications. Limitations due to electrical length, low radiative resistance, high Q-factor, narrow bandwidth, feeding difficulties are among the numerous challenges confronting the feasibility of designing small antennas. Therefore, the intent of this work is to develop an alternative antenna structure that meets the compact requirements in terms of size, without compromising the antenna radiation characteristics. Three antenna designs configurations are developed. The first design is a simple single quasi-lumped element resonator antenna arrangement which was excited by a coaxial feed probe. The antenna structure was photo-edged on a Duroid RO4003C with a permittivity of 3.38 and thickness of 0.813 mm. The size of the resonator is 5.8×5.6 mm2 with conductor thickness of 0.035 mm. The simulation, fabrication, and measurement were conducted to ascertain its performance characteristics thereby validating the inherent potential of the proposed resonator as an antenna candidate. The design and radiation equations were presented. Based on the performance of the first configuration, a 6-element series array quasi-lumped element resonator antenna and the rectangular planar array were designed, fabricated and measured. The latter configuration was excited by the coaxial feed probe, whereas the former was fed by a microstrip-line and excited with a coaxial feed probe

Metamaterial antennas for cognitive radio applications

Cognitive radio is one of the most promising techniques to efficiently utilize the radio frequency (RF) spectrum. As the Digital Video Broadcasting-Handheld (DVB-H) band is targeted (470-862 MHz), the size of the antenna becomes challenging. Metamaterial concept is used as a miniaturization technique. Two antennas are designed, fabricated and measured. The first one achieved multiband operation by loading it with a metamaterial unit cell. These bands are controlled by engineering the dispersion relation of the unit cell. The second one, which is a 2-lumped elements loaded antenna, achieved wideband operation through the entire DVB-H band with a planar size of 5×2 cm^2. A model is proposed to explain, through simple numerical simulations and an optimization algorithm, the behavior of these component loaded antennas (which are equivalent to metamaterial inspired electrically small antennas)

An Inter digital- Poison Ivy Leaf Shaped Filtenna with Multiple Defects in Ground for S-Band bandwidth Applications

The proposed work, a filtenna for s band application is implemented. It is designed by embedding an Interdigital band pass filter (IDBPF) and leaf shaped antenna which are operated in S band. The IDFBPF is having seven resonators with one end shorted through dual vias. It offers a bandwidth of 1.3GHz from 1.65GHz to 2.95GHz.  A Dumbbell shaped DGS (Defected Ground Structure) provided in ground to improve the filter characteristics.  Measured pass (BRL) band return loss (S11) & insertion loss (S12) are -18dB & -4.6dB correspondingly. Further, leaf shaped antenna is designed based on modified polar transformation equation; it has 2.7 GHz bandwidth from 1.3 GH to 3 GHz and has a gain of -5.45dBi, and return loss (S11) of -19.5 dB. The filtenna is obtained by integrating the IDBBPF in the fodder line of the leaf designed antenna. The final model has 1.2 GHz operating bandwidth from 02.30 GHz to 03.50 GHz with peak arrival damages at 2.4GHz and 3.1GHz with -20dB and-24dB respectively. The designed filtenna has a pass band gain of -5.3dBi. The shift in operating band is due to combining the filter with antenna. The proposed model is invented on FR4 substrate having a wideness of 01.60 mm and having a dimension of 0.25 0.58 ?02. In this final model two complementary slip ring resonators (CSRR) are used in addition with four dumbbell structures as defects in the ground plane to avoid ripples in return loss (S11) graph. A high degree of concordance exists between empirically measured and simulated outcomes. The radiation band is showing its application in S band wireless mobile communications, Wi-Fi and ISM 2.4GHz band

Passive Components for Ultra-Wide Band (UWB) Applications

UWB technology brings the convenience and mobility of wireless communications to very high-speed interconnects in the home and office due to the precision capabilities combined with the low power. This makes it ideal for certain radio frequency sensitive environments such as hospitals and healthcare as well as radars. UWB intrusion-detection radar is used for detecting through the wall and also used for security with fuse avoidance radar, precision locating and tracking (using distance measurements between radios), and precision time-of-arrival-based localization approaches. The FCC issued a ruling in 2002 that allowed intentional UWB emissions in the frequency range between 3.1 and 10.6 GHz, subject to certain restrictions for the emission power spectrum. Other definitions for ultra-wideband range of frequency are also used such as any device that has 500 MHz bandwidth or fractional bandwidth greater than 25% is considered an UWB enable high data rate to be transferred with a very low power that does not exceed −41.3 dBm

A Comprehensive Survey of 'Metamaterial Transmission-Line Based Antennas: Design, Challenges, and Applications'

In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (epsilon < 0) and negative permeability (mu < 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called "metamaterials". These artificial structures include series left-handed (LH) capacitances (C-L), shunt LH inductances (L-L), series right-handed (RH) inductances (L-R), and shunt RH capacitances (C-R) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterial-TLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems

A comprehensive survey of "metamaterial transmission-line based antennas: design, challenges, and applications"

In this review paper, a comprehensive study on the concept, theory, and applications of composite right/left-handed transmission lines (CRLH-TLs) by considering their use in antenna system designs have been provided. It is shown that CRLH-TLs with negative permittivity (ε < 0) and negative permeability (μ < 0) have unique properties that do not occur naturally. Therefore, they are referred to as artificial structures called "metamaterials". These artificial structures include series left-handed (LH) capacitances (CL), shunt LH inductances (LL), series right-handed (RH) inductances (LR), and shunt RH capacitances (CR) that are realized by slots or interdigital capacitors, stubs or via-holes, unwanted current flowing on the surface, and gap distance between the surface and ground-plane, respectively. In the most cases, it is also shown that structures based on CRLH metamaterial-TLs are superior than their conventional alternatives, since they have smaller dimensions, lower-profile, wider bandwidth, better radiation patterns, higher gain and efficiency, which make them easier and more cost-effective to manufacture and mass produce. Hence, a broad range of metamaterial-based design possibilities are introduced to highlight the improvement of the performance parameters that are rare and not often discussed in available literature. Therefore, this survey provides a wide overview of key early-stage concepts of metematerial-based designs as a thorough reference for specialist antennas and microwave circuits designers. To analyze the critical features of metamaterial theory and concept, several examples are used. Comparisons on the basis of physical size, bandwidth, materials, gain, efficiency, and radiation patterns are made for all the examples that are based on CRLH metamaterial-TLs. As revealed in all the metematerial design examples, foot-print area decrement is an important issue of study that have a strong impact for the enlargement of the next generation wireless communication systems

Compensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems

Recent technological advances in the RF and wireless industry has led to the design requirement of more sophisticated devices which can meet stringent specifications of bandwidth, data rate and throughput. These devices are required to be extremely sensitive and hence any external interference from other systems can severely affect the device and the output. This thesis introduces the existing problem in nonlinear components in a multi-standard wireless system due to interfering signals and suggests potential solution to the problem. Advances in RF and wireless systems with emerging new communication standards have made reconfigurablility and tunability a very viable option. RF transceivers are optimised for multi-standard operation, where one band of frequency can act as an interfering signal to the other band. Due to the presence of nonlinear circuits in the transceiver chains such as power amplifiers, reconfigurable and tunable filters and modulators, these interfering signals produce nonlinear distortion products which can deform the output signal considerably. Hence it becomes necessary to block these interfering signals using special components. The main objective of this thesis is to analyse and experimentally verify the nonlinear distortions in various RF circuits such as reconfigurable and tunable filters and devise ways to minimize the overall nonlinear distortion in the presence of other interfering signals. Reconfigurbality and tunablity in filters can be achieved using components such as varactor diodes, PIN diodes and optical switches. Nonlinear distortions in such components are measured using different signals and results noted. The compensation method developed to minimize nonlinear distortions in RF circuits caused due to interfering signals is explored thoroughly in this thesis. Compensation method used involves the design of novel microstrip bandstop filters which can block the interfering signals and hence give a clean output spectrum at the final stage. Recent years have seen the emergence of electronic band gap technology which has “band gap” properties meaning that a bandstop response is seen within particular range of frequency. This concept was utilised in the design of several novel bandstop filters using defected microstrip structure. Novel tunable bandstop filters has been introduced in order to block the unwanted signal. Fixed single-band and dual-band filters using DMS were fabricated with excellent achieved results. These filters were further extended to tunable structures. A dual-band tunable filter with miniaturized size was developed and designed. The designed filters were further used in the compensation technique where different scenarios showing the effect of interfering signals in wireless transceiver were described. Mathematical analysis proved the validation of the use of a bandstop filter as an inter-stage component. Distortion improvements of around 10dB have been experimentally verified using a power amplifier as device under test. Further experimental verification was carried out with a transmitter which included reconfigurable RF filters and power amplifier where an improvement of 15dB was achieved

Reconfigurable and multi-functional antennas

This thesis describes a research into multi-frequency and filtering antennas. Several novel antennas are presented, each of which addresses a specific issue for future communication systems, in terms of multi-frequency operation, and filtering capability. These antennas seem to be good candidates for implementation in future multiband radios, cognitive radio (CR), and software defined radio (SDR). The filtering antenna provides an additional filtering action which greatly improves the noise performance and reduces the need for filtering circuitry in the RF front end. Two types of frequency reconfigurable antennas are presented. One is tunable left-handed loop over ground plane and the second is slot-fed reconfigurable patch. The operating frequency of the left handed loop is reconfigured by loading varactor diodes whilst the frequency agility in the patch is achieved by inserting switches in the coupling slot. The length of the slot is altered by activating the switches. Compact microstrip antennas with filtering capabilities are presented in this thesis. Two filtering antennas are presented. Whilst the first one consists of three edge-coupled patches, the second filtering antenna consists of rectangular patch coupled to two hairpin resonators. The proposed antennas combine radiating and filtering functions by providing good out of band gain suppression