Showing papers on "Slot antenna published in 2010"

Microstrip and printed antennas : new trends, techniques, and applications

Abstract: Preface. List of Contributors. Acknowledgments. 1 Numerical Analysis Techniques (Ramesh Garg). 1.1 Introduction. 1.2 Standard (Yee s) FDTD Method. 1.3 Numerical Dispersion of FDTD Algorithms and Hybrid Schemes. 1.4 Stability of Algorithms. 1.5 Absorbing Boundary Conditions. 1.6 LOD-FDTD Algorithm. 1.7 Robustness of Printed Patch Antennas. 1.8 Thin Dielectric Approximation. 1.9 Modeling of PEC and PMC for Irregular Geometries. References. 2 Computer Aided Design of Microstrip Antennas (Debatosh Guha and Jawad Y. Siddiqui). 2.1 Introduction. 2.2 Microstrip Patch as Cavity Resonator. 2.3 Resonant Frequency of Circular Microstrip Patch (CMP). 2.4 Resonant Frequency of Rectangular Microstrip Patch (RMP) with Variable Air Gap. 2.5 Resonant Frequency of an Equilateral Triangular Microstrip Patch (ETMP) with Variable Air Gap. 2.6 Input Impedance of a Microstrip Patch. 2.7 Feed Reactance of a Probe-Fed Microstrip Patch. 2.8 Radiation Characteristics. 2.9 Radiation Efficiency. 2.10 Bandwidth. 2.11 Conclusion. References. 3 Generalized Scattering Matrix Approach for Multilayer Patch Arrays (Arun K. Bhattacharyya). 3.1 Introduction. 3.2 Outline of the GSM Approach. 3.3 Mutual Coupling Formulation. 3.4 Finite Array: Active Impedance and Radiation Patterns. 3.5 Numerical Example. 3.6 Conclusions. 3.7 References. 4 Optimization Techniques for Planner Antennas (Rabindra K. Mishra). 4.1 Introduction. 4.2 Basic Optimization Concepts. 4.3 Real Coded Genetic Algorithm (RCGA). 4.4 Neurospectral Design of Rectangular Patch Antenna. 4.5 Inset-fed Patch Antenna Design Using Particle Swarm Optimization. 4.6 Conclusion. References. 5 Microstrip Reflectarray Antennas (Jafar Shaker and Reza Chaharmir). 5.1 Introduction. 5.2 General Review of Reflectarrays: Mathematical Formulation and General Trends. 5.3 Comparison of Reflectarray and Conventional Parabolic Reflector. 5.4 Cell Elements and Specific Applications: A General Survey. 5.5 Wideband Techniques for Reflectarrays. 5.6 Development of Novel Loop-Based Cell Elements. 5.7 Conclusion. References. 6 Reconfigurable Microstrip Antennas (Jennifer T. Bernhard). 6.1 Introduction. 6.2 Substrate Modification for Reconfigurability. 6.3 Conductor Modification for Reconfigurability. 6.4 Enabling Reconfigurability: Considerations for Reconfiguration Mechanisms. 6.5 Future Trends in Reconfigurable Microstrip Antenna Research and Development. References. 7 Wearable Antennas for Body Area Networks (Peter S. Hall and Yang Hao). 7.1 Introduction. 7.2 Sources on the Human Body. 7.3 Narrowband Antennas. 7.4 Fabric Antennas. 7.5 Ultra Wideband Antennas. 7.6 Multiple Antenna Systems. 7.7 Conclusion. References. 8 Printed Antennas for Wireless Communications (Satish K. Sharma and Lotfollah Shafai). 8.1 Introduction. 8.2 Broadband Microstrip Patch Antennas. 8.3 Patch Antennas for Multiband Wireless Communications. 8.4 Enhanced Gain Patch Antennas. 8.5 Wideband Compact Patch Antennas. 8.6 Microstrip Slot Antennas. 8.7 Microstrip Planar Monopole Antenna. References. 9 UHF Passive RFID Tag Antennas (Daniel Deavours and Daniel Dobkin). 9.1 Introduction. 9.2 Application Requirements. 9.3 Approaches. 9.4 Fabrication. 9.5 Conclusion. References. 10 Printed UWB Antennas (Zhi Ning Chen, Xianming Qing and Shie Ping See). 10.1 Introduction. 10.2 Swan Antenna with Reduced Ground Plane Effect. 10.3 Slim UWB Antenna. 10.4 Diversity Antenna. 10.5 Printed Slot UWB Antenna and Band-Notched Solutions. References. 11 Metamaterial Antennas and Radiative Systems (Christophe Caloz). 11.1 Introduction. 11.2 Fundamentals of Metamaterials. 11.3 Leaky-Wave Antennas. 11.4 Resonant Antennas. 11.5 Exotic Radiative Systems. References. 12 Defected Ground Structure for Microstrip Antennas (Debatosh Guha, Sujoy Biswas, and Yahia M. M. Antar). 12.1 Introduction. 12.2 Fundamentals of DGS. 12.3 DGS for controlling Microstrip Antenna Feeds and Front-End Characteristics. 12.4 DGS to Control/Improve Radiation Properties of Microstrip Patch Antennas. 12.5 DGS for Reduced Mutual Coupling between Microstrip Array Elements and Associated Improvements. 12.6 Conclusion. Appendix: A Brief DGS Chronology. References. 13 Printed Leaky Wave Antennas (Samir F. Mahmoud and Yahia M. M. Antar). 13.1 Introduction. 13.2 The Leaky Wave as a Complex Plane Wave. 13.3 Radiation Pattern of a Leaky Wave. 13.4 Examples of Leaky Mode Supporting Structures. 13.5 The Excitation Problem. 13.6 Two-Dimensional Leaky Waves. 13.7 Further Advances on a Class of Periodic Leaky Wave Antennas. References. Appendix I Preliminary Ideas: PTFE-Based Microwave Lamiantes and Making Prototypes. Appendix II Preliminary Ideas: Microwave Connectors for Printed Circuits and Antennas. Index.

Dual-Band Circularly Polarized $S$ -Shaped Slotted Patch Antenna With a Small Frequency-Ratio

Abstract: A dual-band single-feed circularly polarized, S-shaped slotted patch antenna with a small frequency-ratio is proposed for GPS applications. An S-shaped slot is cut at the centre of a square patch radiator for dual-band operation. A single microstrip feed-line is underneath the center of the coupling aperture ground-plane. The frequency-ratio of the antenna can be controlled by adjusting the S-shaped slot arm lengths. The measured 10-dB return loss bandwidths for the lower and upper-bands are 16% (1.103-1.297 GHz) and 12.5% (1.444-1.636 GHz), respectively. The measured 3-dB axial-ratio (AR) bandwidth is 6.9% (1.195-1.128 GHz) for the lower-band and 0.6% (1.568-1.577 GHz) for the upper-band. The measured gain is more than 5.0 dBic over both the bands. The measured frequency-ratio is 1.28. The overall antenna size is 0.46 ?o × 0.46?o × 0.086?o at 1.2 GHz.

Broadband CPW-Fed Circularly Polarized Square Slot Antenna With Lightening-Shaped Feedline and Inverted-L Grounded Strips

Abstract: A novel design is described for a circularly polarized square slot antenna (CPSSA). Circular polarization (CP) operations can be attained using a lightening-shaped feedline protruded from the signal line of the feeding coplanar waveguide (CPW). The CP bandwidth can be significantly enhanced by implanting a pair of inverted-L grounded strips into the slot and adjusting the dimensions of the lightening-shaped feedline, whereas the impedance bandwidth can be greatly enlarged through tuning embedded vertical and horizontal stubs. The designed antenna was measured to exhibit a CP bandwidth of as high as 48.8%.

A Compact Microstrip Slot Triple-Band Antenna for WLAN/WiMAX Applications

Abstract: A compact triple-band microstrip slot antenna applied to WLAN/WiMAX applications is proposed in this letter. This antenna has a simpler structure than other antennas designed for realizing triple-band characteristics. It is just composed of a microstrip feed line, a substrate, and a ground plane on which some simple slots are etched. Then, to prove the validation of the design, a prototype is fabricated and measured. The experimental data show that the antenna can provide three impedance bandwidths of 600 MHz centered at 2.7 GHz, 430 MHz centered at 3.5 GHz, and 1300 MHz centered at 5.6 GHz.

Terahertz antenna based on graphene

Abstract: We have investigated several configurations of antennas based on graphene. We show that patterned metallic dipole antennas or arrays of dipole antennas deposited on graphene highly benefit from the reversible high-resistivity-to-low-resistivity transition in graphene, tuned by a gate voltage. The radiation pattern and the efficiency of such antennas are changed via the gate voltage applied on graphene.

A Comparison of a Wide-Slot and a Stacked Patch Antenna for the Purpose of Breast Cancer Detection

Abstract: A wide-slot UWB antenna is presented for intended use in the detection scheme being developed at the University of Bristol, based on the principle of synthetically focused UWB radar using a fully populated static array. The antenna's measured and simulated, input and radiation characteristics are presented and compared to an existing, stacked patch antenna that has been designed for the same purpose. The results of this study show that the wide-slot antenna has excellent performance across the required frequency range. Compared to the stacked-patch antenna used in our previous array, the wide-slot antenna can be 3 times smaller (in terms of front surface). The compact nature of the slot antenna means that the detection array can be densely populated. Additionally, this new antenna offers better radiation coverage of the breast. For angles up to 60° away from bore-sight radiated pulses are almost identical (fidelity >95%), whereas for the patch antenna fidelity falls to 58% at the angular extremes. This uniform radiation into the breast should result in focused images with low levels of clutter.

RF MEMS Integrated Frequency Reconfigurable Annular Slot Antenna

Abstract: A new kind of double- and single-arm cantilever type DC-contact RF MEMS actuators has been monolithically integrated with an antenna architecture to develop a frequency reconfigurable antenna. The design, microfabrication, and characterization of this ?reconfigurable antenna (RA) annular slot? which was built on a microwave laminate TMM10i ( ?r = 9.8, tan ? = 0.002), are presented in this paper. By activating/deactivating the RF MEMS actuators, which are strategically located within the antenna geometry and microstrip feed line, the operating frequency band is changed. The RA annular slot has two reconfigurable frequencies of operation with center frequencies f low = 2.4 GHz and f high = 5.2 GHz, compatible with IEEE 802.11 WLAN standards. The radiation and impedance characteristics of the antenna along with the RF performance of individual actuators are presented and discussed.

A Dual-Polarization Slot Antenna Using a Compact CPW Feeding Structure

Abstract: A dual-polarization coplanar waveguide (CPW)-fed slot antenna is proposed in this letter. By exploiting the even and odd modes of a CPW structure, two orthogonal polarizations can be excited in a slot aperture by the same feeding CPW, which results in a compact dual-polarization antenna design with very good isolation between the ports. The -10-dB reflection coefficient bandwidths of two polarizations are 670 MHz (27.9%) for one polarization and 850 MHz (35.4%) for the other, and the isolation between the two ports in the WLAN band is better than -32.6 dB. The radiation pattern and efficiency of the proposed antenna are also measured, and radiation pattern data are compared with simulation results.

Miniaturized Substrate Integrated Waveguide Slot Antennas Based on Negative Order Resonance

Abstract: Miniaturized waveguide slot antennas using negative order resonance are proposed and developed in this paper. The design of these novel resonant-type antennas is based on the study of a composite right/left-handed (CRLH) substrate integrated waveguide (SIW) starting from the dispersion diagram and the equivalent circuit. These proposed CRLH resonators are realized by etching the interdigital slot on the surface of the SIW. The slot acts as a series capacitor as well as a radiator leading to a CRLH antenna application. Two types of slot antennas, which are open-ended and short-ended, respectively, are proposed and discussed. The short-ended antenna, which represents a quasi-quarter-wavelength resonator, is characterized by a cavity-backed slot antenna thus providing a high gain. On the other hand, the open-ended antenna exhibits a small size owing to a quasi-half-wavelength operation in the left-handed (LH) region. Four antennas with one or two unit cells are fabricated and measured. Compared with the existing CRLH patch antennas and waveguide slot antennas, our antennas show advantages in terms of simplicity, low-profile, high efficiency, easy fabrication and integration with other circuits.

Multiband composite right and left handed (crlh) slot antenna

Abstract: This application relates to slot antenna devices based on Composite Right and Left Handed (CRLH) metamaterial (MTM) structures.

Bandwidth Enhancement of Printed E-Shaped Slot Antennas Fed by CPW and Microstrip Line

Abstract: Two printed wide-slot antennas with E-shaped patches and slots, for broadband applications, are proposed They are fed by a coplanar waveguide (CPW) and a microstrip line with almost the same performances Detailed simulation and experimental investigations are conducted to understand their behaviors and optimize for broadband operation Good agreement between the measurement and simulation has been achieved The impedance bandwidths, determined by 10-dB reflection coefficient, of the proposed slot antennas fed by microstrip line and CPW, from both measurement and simulation, are about 136% (285 to 1512 GHz) and 146% (283 to 182 GHz), respectively This large operating bandwidth is obtained by choosing suitable combinations of feed and slot shapes In order to achieve wider operation bandwidth both of the designed antennas have round corners on the wide slot and patch Meanwhile, the proposed antennas exhibit almost omnidirectional radiation patterns, relatively high gain, and low cross polarization A comprehensive numerical sensitivity analysis has been done to understand the effects of various dimensional parameters and to optimize the performance of the designed antennas Results for reflection coefficient, far-field E and H-plane radiation patterns, and gain of the designed antennas are presented and discussed

UWB, Non Dispersive Radiation From the Planarly Fed Leaky Lens Antenna— Part 1: Theory and Design

Abstract: An efficient directive antenna is described that can be used to realize essentially non dispersive links over extremely large bandwidths. The antenna is a significantly enhanced version of previously proposed Leaky Lens antennas that use a frequency independent leaky slot radiation mechanism. A theoretical breakthrough now allows the use of this mechanism also in the presence of purely planar structures. This step allows the realization of the feed of a leaky lens antenna in a unique planar structure that is then glued to a standard circularly symmetric elliptical dielectric lens, as integrated technology requires in the mm and sub-mm wave domains. The first part of this sequence deals with a theoretical breakthrough, the consequent antenna concept and a description of the basic physical mechanisms inside and outside the lens antenna. It is shown that Leaky Lens antennas have the potential to be used to realize antenna links over bands exceeding a decade with minimal dispersion, high efficiency and high directivity. The second part of this sequence deals with the demonstration of these claims via the measurement of two prototypes.

UWB Circular Slot Antenna Provided with an Inverted-L Notch Filter for the 5 GHz WLAN Band

Abstract: —The study of a planar circular slot antenna for Ultrawideband (UWB) communications is presented. The integration on this antenna of a notch filter, to reduce the possible interferences with the 5GHz WLAN communications, has been discussed in detail. Four different structures, achieved by etching a suitable pattern on the antenna circular stub, have been considered, and their features have been compared. The antenna with symmetrical and inverted-L cuts shows the best performance, and it has been therefore realized and fully characterized. It shows very good matching features over the UWB band, and notable rejection of the 5 GHz WLAN band.

Bandwidth Enhancement Method for Low Profile E-Shaped Microstrip Patch Antennas

Abstract: A simple bandwidth enhancement method for low profile E-shaped patch antennas is presented. By introducing a distributed LC circuit to the E-shaped patch antenna, a new resonant frequency close to that of the E-shaped patch is obtained, thus the bandwidth is widened. Moreover, the air thickness of the E-shaped patch antennas is reduced to only 0.0344λ0. A prototype antenna operated at AMPS band (824-894 MHz) was fabricated and measured. Measured results show that the designed low profile antenna has an impedance bandwidth over 9% for VSWR<; 2, with a satisfactory radiation performance within the bandwidth. The proposed method is also applicable to the design of other types of low profile slot-loaded patch antennas.

Polarization Reconfigurable Slot Antenna With a Novel Compact CPW-to-Slotline Transition for WLAN Application

Abstract: A polarization reconfigurable slot antenna with a novel coplanar waveguide (CPW)-to-slotline transition for wireless local area networks (WLANs) is proposed and tested. The antenna consists of a square slot, a reconfigurable CPW-to-slotline transition, and two p-i-n diodes. No extra matching structure is needed for modes transiting, which makes it much more compact than all reference designs. The -10 dB bandwidths of an antenna with an implemented bias circuit are 610 (25.4%) and 680 MHz (28.3%) for vertical and horizontal polarizations, respectively. The radiation pattern and gain of the proposed antenna are also tested, and the radiation pattern data were compared to simulation results.

Reducing Mutual Coupling for an Extremely Closely-Packed Tunable Dual-Element PIFA Array Through a Resonant Slot Antenna Formed In-Between

Abstract: An efficient mutual coupling reduction method is introduced for an extremely closely packed tunable dual-element planar inverted-F antenna (PIFA) array. High isolation can be achieved through a λ0/2 folded slot antenna formed by a slot on the ground plane and the neighboring edges of the two PIFAs. Direct coupling is blocked by the slot antenna through radiating the coupling power into free space. A measured isolation of more than 36.5 dB can be achieved between the two parallel individual-element PIFAs operating at 2.4 GHz WLAN band with an inter-PIFA spacing of less than 0.063 λ0 (center to center) or 0.0147 λ0 (edge to edge). Since there is only a narrow slot antenna formed between the PIFAs in the present method, the distance can be further reduced to less than 0.0016λ0 (edge to edge) with the maximal isolation of better than 40 dB. Both measured and simulation results show the effectiveness of the present mutual coupling reduction method.

A Simple Compact Reconfigurable Slot Antenna With a Very Wide Tuning Range

Abstract: A simple and compact slot antenna with a very wide tuning range is proposed. A 25 mm (roughly equal to λH/8, where λH corresponds to the highest frequency of the tuning range) open slot is etched at the edge of the ground. To achieve the tunability, only two lumped elements, namely, a PIN diode and a varactor diode are used in the structure. By switching the PIN diode placed at the open end of the slot, the slot antenna can resonate as a standard slot (when the switch is on) or a half slot (when the switch is off). Continuous tuning over a wide frequency range in those two modes can be achieved by adjusting the reverse bias (giving different capacitances) of the varactor diode loaded in the slot. Through optimal design, the tuning bands of the two modes are stitched together to form a very wide tuning range. The fabricated prototype has a tuning frequency range from 0.42 GHz to 1.48 GHz with Sll better than -10 dB, giving a frequency ratio (fR = fu/fL) of 3.52:1. The measured full spherical radiation patterns show consistent radiation characteristics of the proposed antenna within the whole tuning range.

High-Efficiency Dual-Band On-Chip Rectenna for 35- and 94-GHz Wireless Power Transmission in 0.13- $\mu{\hbox {m}}$ CMOS Technology

Abstract: This paper proposes a high-efficiency dual-band on-chip rectifying antenna (rectenna) at 35 and 94 GHz for wireless power transmission. The rectenna is designed in slotline (SL) and finite-width ground coplanar waveguide (FGCPW) transmission lines in a CMOS 0.13-μm process. The rectenna comprises a high gain linear tapered slot antenna (LTSA), an FGCPW to SL transition, a bandpass filter, and a full-wave rectifier. The LTSA achieves a VSWR=2 fractional bandwidth of 82% and 41%, and a gain of 7.4 and 6.5 dBi at the frequencies of 35 and 94 GHz. The measured power conversion efficiencies are 53% and 37% in free space at 35 and 94 GHz, while the incident radiation power density is 30 mW/cm2 . The fabricated rectenna occupies a compact size of 2.9 mm2.

A New Wideband Circularly Polarized Hybrid Dielectric Resonator Antenna

Abstract: Dielectric resonator antennas (DRAs) have been targeted in the past two decades as a potential solution for wideband antennas. Although DRAs offer wider frequency band and smaller size than patch antennas, their design to obtain good circular polarization over a wide frequency band can be challenging. In this letter, a new hybrid DRA has been investigated to produce circular polarization over a wide frequency band. The targeted application is to produce a compact antenna for satellite navigation systems. The obtained design was fabricated and measured, showing impedance matching from 1.08 to 1.82 GHz, i.e. over 50% bandwidth. The radiation characteristics of the antennas were also characterized. The achieved gain is over 1.5 dBic, and the axial ratio (AR) is under 1 dB at boresight over the 1.131.63 GHz frequency band. The half-power beamwidth is greater than 75°, and the axial ratio beamwidth (AR < 3 dB) is over 100° .

Wideband L-Shaped Circular Polarized Monopole Slot Antenna

Abstract: A wideband circularly polarized L-shaped monopole slot antenna with a single C-shaped feed is designed and fabricated. The measured results demonstrate that the antenna has an axial ratio (AR)<; 3dB, a reflection coefficient <; -10dB, and 23% circular polarization (CP) bandwidth. The monopole quarter-wavelength slot antenna design occupies half of the area on the corner of circuit board as compared to a half-wavelength slot antenna that requires double the area at the center of the board. This feature is attractive for compact wireless devices that operate at low frequencies in which planning for the smallest circuit board area combined with the shortest length for signal routing are the two major concerns. The antenna is extremely low-cost and does not require any truncation corner, reflector surfaces, or via connections, all of which increase the fabrication cost.

Modal Analysis and Design of Band-Notched UWB Planar Monopole Antennas

Abstract: The theory of characteristic modes is proposed for the analysis of simple band-notched UWB planar monopole antennas, since the information provided by these real modes (i.e. resonant frequency and radiating bandwidth) provides a very interesting physical insight into the radiation phenomena taking place in this type of antennas. Such an in-depth understanding paves the way for the proposal of novel designs of UWB antennas with increased functionality, through the control of the excitation and resonance of specific modes. Modal analysis of band-notched UWB antennas illustrates the existence of resonant modes linked to the embedded narrowband slot structure (slot modes), whose location within the planar geometry of the monopole determines the effect over the rest of the radiating modes of the wideband structure, and consequently, over the behavior of the antenna. By electronically controlling the excitation of the first slot mode, an UWB antenna with switchable band-notched behavior is proposed. Similarly, a tunable band-notched UWB antenna can be proposed by controlling the resonance of this slot mode. Prototypes for both the switchable and tunable band-notched antenna have been fabricated and measured, demonstrating the expected behavior. The understanding of the radiating behavior of this type of antennas can be easily extrapolated to other configurations, such as coplanar band-notched UWB antennas, which are more compact than the designs presented here, and may help to propose other antennas of this type.

Compact Slot Antenna for UWB Applications

Abstract: A novel compact microstrip-fed slot antenna design is proposed. By properly loading a notch to the open-ended T-shaped slot and extending a small section to the microstrip feed line, multiple resonant frequencies are excited and merged to form a large enough 10-dB return loss bandwidth (measured from 3.1 to 11.45 GHz) for ultrawideband (UWB) applications. The vital parameters of the proposed antenna are illustrated, and a prototype is constructed and experimentally studied. The measured results show good radiation patterns and stable signal transmission within the band of interest.

A Novel Switchable Single- and Multifrequency Triple-Slot Antenna for 2.4-GHz Bluetooth, 3.5-GHz WiMax, and 5.8-GHz WLAN

Abstract: A novel reconfigurable slot antenna with three switchable frequencies is presented. The uniqueness of this design is that it allows various groups of its frequency resonances to be selected electronically using three switches. Therefore, seven different states are achieved, and so three, two, or one resonances are possible at the same time. By using three sickle-shaped slots in the ground plane and three pairs of p-i-n diodes that are soldered between three metal strips inside the slots and the ground plane, the antenna can support 2.4-GHz Bluetooth and/or 3.5-GHz WiMAX and/or 5.8-GHz WLAN systems. The advantage of this design is that it overcomes the problem of conventional reconfigurable antennas of serving one frequency band at a time. The antenna design, simulation, and measurement results are presented. The antenna shows similar radiation patterns with low cross-polarization levels at all its operating frequencies. The simulated and measured results are in good agreement.

Low Cost Planar Waveguide Technology-Based Dielectric Resonator Antenna (DRA) for Millimeter-Wave Applications: Analysis, Design, and Fabrication

Abstract: A compact, low cost and high radiation efficiency antenna structure, planar waveguide, substrate integrated waveguide (SIW), dielectric resonator antennas (DRA) is presented in this paper. Since SIW is a high Q- waveguide and DRA is a low loss radiator, then SIW-DRA forms an excellent antenna system with high radiation efficiency at millimeter-waveband, where the conductor loss dominates. The impact of different antenna parameters on the antenna performance is studied. Experimental data for SIW-DRA, based on two different slot orientations, at millimeter-wave band are introduced and compared to the simulated HFSS results to validate our proposed antenna model. A good agreement is obtained. The measured gain for SIW-DRA single element showed a broadside gain of 5.51 dB,-19 dB maximum cross polarized radiation level, and overall calculated (simulated using HFSS) radiation efficiency of greater than 95%.

Modeling, Design and Characterization of a Very Wideband Slot Antenna With Reconfigurable Band Rejection

Abstract: An antenna exhibiting a very wide bandwidth with reconfigurable rejection within the band is presented. The proposed topology is versatile in terms of the number of available antenna states and location of the rejection frequencies, and also allows the operation of the antenna in an “all-pass” state. First, a physical interpretation of the rejection mechanism and its corresponding circuit model are presented and validated. The proposed antenna concept is then demonstrated on a 4-state slot bow-tie antenna operating from 1.5 to 5 GHz with various rejection frequencies. PIN diodes are used as switching elements, with particular care taken to minimize power consumption. Simulated and measured return loss, radiation patterns and gain of the fully operational antenna are presented. Finally, we characterize and discuss the overall efficiency-considered here as the most relevant parameter to characterize the antenna filtering performance-both theoretically and experimentally, thereby highlighting the benefit of the proposed topology.

Tunable SIW Cavity Backed Active Antenna Oscillator

Abstract: A substrate integrated waveguide (SIW) cavity backed active slot antenna oscillator is proposed, the operation frequency of which can be tuned by means of a properly connected varactor. The cavity backed structure permits overcoming potential problems such as heat dissipation and unwanted surface wave modes in large array implementations, and may provide better phase noise performance. The use of SIW technology permits a cost-effective fabrication process and simple implementation at millimetre-wave frequency, for radar and communication applications. Full-wave FEM-based analysis is used for the design of the radiating structure, while harmonic balance and transient simulations are employed in the design of the active antenna oscillator and in the study of the stability of its steady-state solutions. Tunable active antenna prototypes have been implemented and measured.

Study and Design of a Differentially-Fed Tapered Slot Antenna Array

Abstract: The results of a parametric study and design of an ultrawideband dual-polarized array of differentially-fed tapered slot antenna elements are presented. We examine arrays of bunny-ear antennas and discuss the capabilities and limitations of differential antenna technology. As we focus on radio astronomical applications, the absence of a balancing-feed circuit not only reduces the first-stage noise contribution associated to losses in the feed, but also leads to a cost reduction. Common-modes are supported by the antenna structure when a third conductor is present, such as a ground plane. We demonstrate that anomalies may occur in the differential-mode scan impedance. Knowledge of both types of scan impedances, differential and common mode, is required to properly design differential LNAs and to achieve optimal receiver sensitivity. A compromise solution is proposed based on the partial suppression of the undesired common-mode currents through a (low loss) balancing-dissipation technique. A fully steerable design up to 45° in both principal planes is achieved.

Experimental Characterization of UWB On-Body Radio Channel in Indoor Environment Considering Different Antennas

Abstract: An experimental investigation to characterize the transient and spectral behavior of the ultrawideband (UWB) on-body radio propagation channel for body-centric wireless communications is presented. The measurements were performed considering over thirty on-body links in the front of human body in the anechoic chamber, and in indoor environment. Two different pairs of planar antennas have been used, namely, CPW-fed planar inverted cone antennas (PICA), and miniaturized CPW-fed tapered slot antennas (TSA). A path loss model is extracted from measured data, and a statistical study is performed on the time delay parameters. The goodness of different statistical models in fitting the root mean square (RMS) delay has been evaluated. Results demonstrate that the TSA, due to its more directive radiation behavior is less affected from the reflections from body parts and surrounding environment. The antenna shows significant size reduction and improved time delay behavior, and hence is an ideal candidate for UWB body area networks (BAN).

Multi-slot antenna and mobile device

Abstract: A mobile communications device having a patch antenna which has defined therein at least two slots each having two or more parts. The at least two slots may include an L-shaped slot and a C-shaped slot, wherein the slots can be open or closed. The L-shaped slot may be an open-slot projecting into the patch antenna from the edge. Ground and signal connections may be at the edge of the patch on either side of the L-shaped slot. The C-shaped slot may be nested within the L-shaped slot.