Showing papers on "Coaxial antenna published in 2010"

Balanced Antipodal Vivaldi Antenna With Dielectric Director for Near-Field Microwave Imaging

Abstract: A balanced antipodal Vivaldi antenna is designed to be used as a sensor for a microwave breast cancer detection system. The antenna has the ability to send short electromagnetic pulses into the near-field, with low distortion, low loss and in a directional manner. The antenna directivity is further improved by the inclusion of a novel feature in the antenna aperture called a “director” which consists of a profiled piece of higher dielectric constant material. Several simulated results are successfully confirmed with measurements. Reflections of a tumor placed in a breast model are simulated for two cases, namely a balanced antipodal Vivaldi antenna with and without a director. Greater tumor responses are recorded with the director present, demonstrating the potential of this feature for microwave breast imaging.

High gain metamaterial antenna device

Abstract: An antenna is presented having a flared structure wherein charge is induced from one portion of the structure to another. The flared structure may be a V-shaped or other shaped element. The antenna includes at least one parasitic element to increase the gain of the antenna and extend the radiation pattern generated by the antenna in a given direction.

System and methods for antenna optimiazation for wireless broadband communication

Abstract: A system and method for antenna optimization for wireless broadband communication is provided. Such an enhanced antenna array includes higher-gain antenna and lower-gain antenna. The beamforming antenna, both higher-gain and lower-gain, are designed to be able to transmit to and receive from another transceiver. The higher-gain antenna may be designed to form a more directional beam substantially closer to the horizon; whereas the lower-gain antenna is capable of forming a less directional beam at a distance further from the horizon. In both cases, the antenna may form their respective beams anywhere in the 360 degrees horizontally around the antenna array. The higher-gain antenna may include a coverage area from the horizon to a substantially acute angle from the horizon in the vertical direction. In contrast, the lower-gain antenna may have coverage from the substantially acute angle from the horizon to substantially vertical. The substantially acute angle may be approximately 10 degrees in some cases. In some cases the lower-gain antenna may include four elements. Likewise, in some embodiments, the higher-gain antenna may include four elements as well.

Novel CPW-Fed Planar Monopole Antenna for WiMAX/WLAN Applications

Abstract: A coplanar waveguide (CPW)-fed planar monopole antenna with triple-band operation for WiMAX and WLAN applications is presented. The antenna, which occupies a small size of 25(L) × 25(W) × 0.8(H) mm3, is simply composed of a pentagonal radiating patch with two bent slots. By carefully selecting the positions and lengths of these slots, good dual stopband rejection characteristic of the antenna can be obtained so that three operating bands covering 2.14-2.85, 3.29-4.08, and 5.02-6.09 GHz can be achieved. The measured results also demonstrate that the proposed antenna has good omnidirectional radiation patterns with appreciable gain across the operating bands and is thus suitable to be integrated within the portable devices for WiMAX/WLAN applications.

Polarization Reconfigurable U-Slot Patch Antenna

Abstract: A compact U-slot microstrip patch antenna with reconfigurable polarization is proposed for wireless local area network (WLAN) applications. PIN diodes are appropriately positioned to change the length of the U-slot arms, which alters the antenna's polarization state. Two antenna prototypes with identical dimensions are designed, fabricated and measured. The first antenna prototype enables switching between linear and circular polarization by using a PIN diode and a capacitor located on the U-slot. The second antenna prototype uses two PIN diodes to switch between the two circular polarization senses. A good impedance match (S11 ≤-10 dB) for both linear and circular polarization is achieved from 5.725 to 5.85 GHz, a band typically used for WLAN applications, and the 3 dB axial ratio bandwidth is greater than 2.8%. Details of the simulated and measured reflection coefficient, axial ratio, gain and radiation patterns are presented.

Low-Cost High Gain Planar Antenna Array for 60-GHz Band Applications

Abstract: An effective development of a class of low-cost planar antenna arrays having a high reproducibility is presented for 60-GHz band system applications. The proposed antenna arrays, based on the substrate integrated waveguide (SIW) scheme, consists of one compact SIW 12-way power divider and 12 radiating SIWs each supporting 12 radiating slots. A 50-? conductor-backed coplanar waveguide (CBCPW) integrated with CBCPW-to-SIW transition is directly used as the input of the antenna array, thus allowing to accommodate other circuits or MMICs at a minimum cost. An antenna array prototype was implemented on Rogers RT/Duroid 6002 substrate with thickness of 20 mils by our standard PCB process. Measured gain is about 22 dBi with a side lobe suppression of 25 dB in the H-plane and 15 dB in the E-Plane while the bandwidth for the 10-dB return loss is 2.5 GHz.

Periodic Leaky-Wave Antenna for Millimeter Wave Applications Based on Substrate Integrated Waveguide

Abstract: Substrate integrated waveguides (SIW) are built up of periodically arranged metallic via-holes or via-slots The leakage loss of SIW structures increases with the distance between the via-holes or via-slots An open periodic waveguide with a large via distance supports the propagation of leaky-wave modes and can thus be used for the design of a leaky-wave antenna In this paper, this leakage loss is studied in detail and used to design a periodic leaky-wave antenna The proposed concept represents an excellent choice for applications in the millimeter-wave band Due to its versatility, the finite difference frequency domain method for periodic guided-wave or leaky-wave structures is used to analyze the characteristics of the proposed periodic leaky-wave antenna Two modes (TE10 and TE20) are investigated and their different leaky-wave properties are analyzed Based on the proposed leaky-mode analysis method, a novel periodic leaky-wave antenna at 28-34 GHz is designed and fabricated

Balanced metamaterial antenna device

Abstract: This document describes designs and techniques for directly feeding an unbalanced transmission line with a balanced antenna using Composite Right and Left Handed (CRLH) and balun structures.

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.

Wideband Circularly Polarized Trapezoidal Dielectric Resonator Antenna

Abstract: A wideband circularly polarized (CP) trapezoidal dielectric resonator antenna (DRA) is investigated in this letter. The DRA is simply excited by a single 45° inclined slot fed by a microstrip feed line. It is found that the 3-dB axial ratio (AR) bandwidth of the proposed antenna can be as wide as 21.5%. The antenna gain varies between 5.28 and 8.40 dBi across the antenna passband (3.11-3.86 GHz). This letter also presents a modified trapezoidal DRA that has a notch at its top. The modified version improves the impedance match, as the AR and gain remain almost unchanged. The reflection coefficient, AR, radiation pattern, and antenna gain of each proposed configuration are studied, and reasonable agreement between the measured and simulated results is observed.

Compact Monopole Antenna With Band-Notched Characteristic for UWB Applications

Abstract: A compact planar monopole antenna with standard band-notched characteristic suitable for ultrawideband (UWB) applications is presented. This microstrip-fed antenna, consisting of a square slot patch with a vertical coupling strip, only occupies a small size of 15 (L) × 15 (W) × 1.6 (H) mm3. By properly designing the strip placed at the center of the patch, good frequency rejection performance of the antenna with a wide operating band from 3.05 to 11.15 GHz can be obtained. Compared to other designs, the antenna has a quite simple structure to make the band-notched property to reduce the effect caused by the frequency interference. Furthermore, fairly good omnidirectional radiation patterns and transmission responses both indicate that the proposed antenna is well suited to be integrated within various portable devices for UWB operation.

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.

Frequency Reconfigurable Quasi-Yagi Folded Dipole Antenna

Abstract: A frequency reconfigurable planar quasi-Yagi antenna with a folded dipole driver element is presented. The center frequency of the antenna is electronically tuned by changing the effective electrical length of the folded dipole driver, which is achieved by employing either varactor diodes or PIN diodes. Two antenna prototypes are designed, fabricated and measured. The first antenna enables continuous tuning from 6 to 6.6 GHz using varactor diodes and the reflection coefficient bandwidth (≤ -10 dB) at each frequency is greater than 15%. The second antenna enables discrete tuning using PIN diodes to operate in either the 5.3-6.6 GHz band or the 6.4-8 GHz band. Similar end-fire radiation patterns with low cross-polarization levels are achieved across the entire tunable frequency range for the two antenna prototypes. Measured results on tuning range, radiation patterns and gain are provided, and these show good agreement with numerical simulations.

Planar loop antenna system

Abstract: An inexpensive planar antenna fabricated as a plurality of parallel layers of multi turn spiral loops co-located with conductive material at the center of the loops, there being an exclusion zone free of conductive material between the innermost loop and the conductive material at the center. The conductive material may comprise circuit elements, for example batteries, amplifiers, antenna drivers or other functional elements as well as passive elements. In one embodiment, the loop traces may be staggered. In another embodiment, the loop traces are varied in width as a function of position within the loop cross section. In further embodiments, the planar form is integrated with additional orthogonal planar antennas substantially coplanar with the first planar antenna and having axes orthogonal to the first planar antenna and to one another. In further embodiments the exclusion zone is extended by design rules and confining routes in a circuit section. The antenna system may be configured as a three dimensional omnidirectional antenna and is well adapted for small form factor hand held and portable wireless applications.

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.

Planar Antenna Array and Article of Manufacture Using Same

Abstract: A planar antenna array and articles of manufacture using the same are disclosed. In one embodiment, close-packed antenna elements, disposed on a substrate, number N where N=3x and x is a positive integer. Each of the close-packed antenna elements includes a substantially continuous photonic transducer arranged as an outwardly expanding generally logarithmic spiral having six turns. Each of the outwardly expanding generally logarithmic spirals may be a golden spiral. As an article of manufacture, the planar antenna array may be incorporated into a chip, such as a cell phone, or an article of clothing, for example.

Vertically Multilayer-Stacked Yagi Antenna With Single and Dual Polarizations

Abstract: There are many applications such as local positioning systems (LPS) and wireless sensor networks that require high-directivity and compact-size or small footprint antennas. The classical Yagi-Uda antenna may be useful in meeting such demands, which however, becomes very large in size to achieve a high-gain performance due to a large number of directors as well as space required between those elements. In this paper, high-gain yet compact stacked multilayered Yagi antennas are proposed and demonstrated at 5.8 GHz for LPS applications. This structure makes use of vertically stacked Yagi-like parasitic director elements that allow easily obtaining a simulated gain of 12 dB. Two different antenna configurations are presented, one based on dipole geometry for single polarization, and the other on a circular patch to achieve dual polarization. The characteristics of these antennas with respect to various geometrical parameters are studied in order to obtain the desired performance. Measured results of the fabricated antenna prototypes are in good agreement with simulated results. The measured dipole Yagi antenna yields 11 dB gain over 14% bandwidth with a size of 80 × 80 × 29 mm3. Radiation patterns of the dual-polarized Yagi antenna are nearly identical to those of the single-polarized antenna, which has a size of 50 × 50 × 60 mm3, and also its two-port isolation is found to be as low as -25 dB over 4% bandwidth. The proposed antennas present an excellent candidate for compact and low-cost microwave and millimeter-wave integrated systems that require fixed or variable polarization capabilities and small surface footprint.

Low-Q Electrically Small Spherical Magnetic Dipole Antennas

Abstract: Three novel electrically small antenna configurations radiating a TE10 spherical mode corresponding to a magnetic dipole are presented and investigated: multiarm spherical helix (MSH) antenna, spherical split ring resonator (S-SRR) antenna, and spherical split ring (SSR) antenna. All three antennas are self-resonant, with the input resistance tuned to 50 ohms by an excitation curved dipole/monopole. A prototype of the SSR antenna has been fabricated and measured, yielding results that are consistent with the numerical simulations. Radiation quality factors (Q) of these electrically small antennas (in all cases ka <; 0.26) approach the limit of 3.0 times the Chu lower bound for a given antenna size, which is in line with a theoretical prediction made by Wheeler in 1958.

A Very Compact Ultrawideband Printed Omnidirectional Monopole Antenna

Abstract: -A new form of the microstrip-fed monopole antenna with truncated ground plane is presented. In comparison to the previous monopole structures, the miniaturized antenna dimension is only about 11 (0.11λr) × 16 mm2 (0.17λr), where λr, is the wavelength of the lowest frequency of the band (i.e., 3.2 GHz). By only sequentially inserting the three notches with proper sizes and positions in two corners of the quasi-square radiating patch, very good radiation and impedance characteristics are obtained. The measured impedance bandwidth of the realized antenna with optimal parameters is from 3.9 to 21.4 GHz (5.5:1, 138%) for VSWR <;1.5. Moreover, unlike the conventional omnidirectional monopole antennas, the stability of the H-plane radiation patterns of the proposed antenna is maintained in omnidirectional form within the frequency bandwidth up to 16 GHz. The improvement process of the impedance and radiation properties is completely presented and discussed.

Cavity antennas for electronic devices

Abstract: Antennas are provided for electronic devices such as portable computers. An electronic device (10) may have a housing (12) in which an antenna is mounted. The housing may have an antenna window (68) for the antenna. The antenna window may be formed from dielectric or from antenna window slots (82) in a conductive member such as a conductive wall of the electronic device housing. An antenna may have an antenna resonating element (70) that is backed by a conductive antenna cavity (72). The antenna resonating element may have antenna resonating element slots or may be formed using other antenna configurations such as inverted-F configurations. The antenna cavity may have conductive vertical sidewalls and a conductive rear wall. The antenna cavity walls may be formed from conductive layers on a dielectric antenna support structure.

Miniature Internal Penta-Band Monopole Antenna for Mobile Phones

Abstract: A compact T-slit monopole antenna with slotted ground plane in the mobile phone for penta-band operation is proposed. In this configuration, the antenna comprises a T-slit monopole printed on the top ungrounded portion of an FR4 substrate of small size of 47 × 5.4 mm2 and a slotted ground plane etched on the back side of the substrate of size of 47 × 10 mm2. In addition, an inverted-L copper strip is soldered to the end edge of the monopole for extending the electrical length of the antenna for GSM band; that is, the proposed antenna occupies a small volume of 47 × 10 × 5 mm3 inside the mobile phone and is suitable to operate as an internal antenna. By controlling the related parameters, the proposed antenna can resonates at different operating bands to cover GSM850/900 and DCS/PCS/UMTS operations independently.

A Novel Hybrid-Fed Patch Antenna With Pattern Diversity

Abstract: -In this letter, a novel hybrid-fed circular patch antenna operating with TM11 and TM01 modes is presented. By making use of a hybrid feed network, the two modes can be operated at an overlapped frequency range for 2.4-GHz WLAN applications, while TM11 mode reveals good broadside radiation patterns and TM01 mode shows monopole-like radiation patterns. The proposed antenna is fabricated and tested. The measured gain for the broadside mode is 7.1-9.1 dBi from 2.16 to 2.72 GHz (23.0%), and for the conical mode 3.4-4.3 dBi from 2.14 to 2.64 GHz (20.5%). High isolation (<; -40 dB) between the two feeding ports for the entire impedance bandwidth of the proposed antenna is achieved. The planar dual-port antenna provides different patterns and polarizations to take advantage of the pattern and polarization diversity for modern mobile communications.

Design of Compact Dual-Wideband Antenna With Assembled Monopoles

Abstract: A coplanar waveguide (CPW)-fed dual-wideband antenna formed by a triangular monopole and a U-shaped monopole is presented. The antenna can generate two wide bands centered at about 2.5 GHz and 5 GHz to cover all the 2.4/5.2/5.8 GHz WLAN bands and the 2.5/3.5/5.5 WiMAX bands. Furthermore, the antenna has a simple planar structure and occupies a small size of about 28 X 33 mm2, including the finite ground CPW feeding mechanism. Good dipole-like radiation characteristics over the operating bands are obtained.

Wideband Circularly Polarized E-Shaped Patch Antenna for Wireless Applications

Abstract: A new technique to achieve a circularly polarized probe-fed single-layer microstrip-patch antenna with a wideband axial ratio is proposed. The antenna is a modified form of the conventional E-shaped patch, used to broaden the impedance bandwidth of a basic patch antenna. 8y letting the two parallel slots of the E patch be unequal, asymmetry is introduced. This leads to two orthogonal currents on the patch and, hence, circularly polarized fields are excited. The proposed technique exhibits the advantage of the simplicity of the E-shaped patch design, which requires only the slot lengths, widths, and position parameters to be determined. Investigations of the effect of various dimensions of the antenna have been carried out via parametric analysis. Based on these investigations, a design procedure for a circularly polarized E-shaped patch was developed. A prototype has been designed, following the suggested procedure for the IEEE 802.11 bIg WLAN band. The performance of the fabricated antenna was measured and compared with simulation results. Various examples with different substrate thicknesses and material types are presented and compared with the recently proposed circularly polarized U-slot patch antennas.

Design of fractal patch antenna for size and radar cross-section reduction

Abstract: This research study presents a novel design of star-shaped fractal patch antenna for miniaturisation and backscattering radar cross-section (RCS) reduction. The proposed fractal antenna gives 50% size reduction compared with a conventional circular microstrip patch (CCMP) antenna. The antenna is studied experimentally for return loss behaviour using vector network analyser R&S ZVA40. It can be useful for wireless application in 0.85-4 GHz frequency band. Further, the study focuses on backscattering RCS (both monostatic and bistatic) reduction by the proposed antenna compared with the CCMP antenna. It is found that increase in number of fractal iterations included in the conventional patch to design fractal antenna geometry reduces backscattering RCS at multiband compared to the conventional patch antenna. This reduction in backscattering RCS by the antenna is observed at multiband. The antenna can be tuned for low backscattering by variation in the substrate dielectric constant and thickness and the superstrate dielectric constant and thickness. For maximum RCS reduction by the antenna, optimisation of substrate thickness becomes necessary. The study also deals with effect of frequency and aspect angle variation on backscattering RCS reduction.

An Improved Design of Planar Elliptical Dipole Antenna for UWB Applications

Abstract: In this letter, an enhanced planar elliptical dipole antenna design for ultrawideband (UWB) communication and impulse radar systems is presented. The printed-circuit-elliptical (PCE) antenna has been investigated to be an effective radiator for UWB applications. To enhance gain and return loss bandwidth of the antenna, elliptical slots are used on the dipole arms. The gain performance of the antenna has been increased by means of elliptical slots in the frequency range from 2.7 to 11 GHz. The standing wave ratio is less than 2 (SWR < 2) along 94.4% of operation bandwidth from 1.1 to 11 GHz. The radiation pattern in E- and H-plane for certain frequencies, the return loss, and the gain performance are presented with the experimental and simulation results. Moreover, the time domain analysis of the antenna is presented. The antenna introduces low-level ringing and pulse distortion. Consequently, the antenna is very useful for impulse and UWB communication systems.

Cost-Effective 60-GHz Antenna Package With End-Fire Radiation for Wireless File-Transfer System

Abstract: This paper proposes a cost-effective antenna package suitable for the mobile terminal of the wireless file-transfer system. The antenna package provides the end-fire radiation from the open-ended post-wall waveguide built into the side of the package. The antenna package, in which a 60-GHz CMOS chip is attached, is mounted on the edge of a printed circuit board by the ball-grid-array assembly. The fabricated antenna, to be built in the package, had the size of 4.8 mm × 6.4 mm × 1.0 mm. The beamwidths of 120° (E-plane) and 72° (H-plane) and the gain of 2.2 dBi were measured at 60 GHz. The cost-effective antenna package with two antennas for the transmitter (Tx) and the receiver (Rx) was fabricated. The isolation between the Tx and Rx antenna was measured to be greater than 36 dB in the frequency range of 59-66 GHz. Moreover, the antenna with higher gain required from the system was fabricated. The gain of 6 dBi in the range of 58-68 GHz was measured. The beamwidth of 60° (E-plane) and 30° (H-plane) at 60 GHz were measured, respectively.

Wideband Circularly Polarized E-Shaped Patch Antenna for Wireless Applications [Wireless Corner]

Abstract: A new technique to achieve a circularly polarized probe-fed single-layer microstrip-patch antenna with a wideband axial ratio is proposed. The antenna is a modified form of the conventional E-shaped patch, used to broaden the impedance bandwidth of a basic patch antenna. By letting the two parallel slots of the E patch be unequal, asymmetry is introduced. This leads to two orthogonal currents on the patch and, hence, circularly polarized fields are excited. The proposed technique exhibits the advantage of the simplicity of the E-shaped patch design, which requires only the slot lengths, widths, and position parameters to be determined. Investigations of the effect of various dimensions of the antenna have been carried out via parametric analysis. Based on these investigations, a design procedure for a circularly polarized E-shaped patch was developed. A prototype has been designed, following the suggested procedure for the IEEE 802.11big WLAN band. The performance of the fabricated antenna was measured and compared with simulation results. Various examples with different substrate thicknesses and material types are presented and compared with the recently proposed circularly polarized U-slot patch antennas.