Showing papers on "Monopole antenna published in 2011"

Design of Triple-Frequency Microstrip-Fed Monopole Antenna Using Defected Ground Structure

Abstract: A novel triple-frequency microstrip-fed planar monopole antenna for multiband operation is proposed and investigated. Defected ground structure (DGS) is used in this antenna, which has a rectangular patch with dual inverted L-shaped strips and is fed by a cross-shaped stripline, for achieving additional resonances and bandwidth enhancements. The designed antenna has a small overall size of 20 × 30 mm2, and operates over the frequency ranges, 2.14-2.52 GHz, 2.82-3.74 GHz, and 5.15-6.02 GHz suitable for WLAN 2.4/5.2/5.8 GHz and WiMAX 3.5/5.5 GHz applications. There is good agreement between the measured and simulated results. Experimental results show that the antenna gives monopole-like radiation patterns and good antenna gains over the operating bands. In addition, effects of both the length of the protrudent strips and the dimensions of the DGS for this design on the electromagnetic performance are examined and discussed in detail.

Miniaturized Triple-Band Antenna With a Defected Ground Plane for WLAN/WiMAX Applications

Abstract: A miniaturized multifrequency antenna is proposed. The proposed antenna can generate three separate impedance bandwidths to cover all the 2.4/5.2/5.8-GHz WLAN operating bands and the 2.5/3.5/5.5-GHz WiMAX bands. The proposed microstrip-fed antenna mainly consists of a circular ring, a Y-shape-like strip, and a defected ground plane. By adding a Y-shape-like strip in the circular ring, the antenna excites two resonant modes and is with miniaturization structure. Because of the introduction of the cambered ground plane with an isosceles triangle-defect, the third wide band with better impedance matching is obtained. A prototype is experimentally tested, and the measured results show good radiation patterns and enough gains across the operation bands.

Compact Tapered-Shape Slot Antenna for UWB Applications

Abstract: A compact microstrip line-fed ultrawideband (UWB) tapered-shape slot antenna is presented. The proposed antenna comprises a tapered-shape slot and rectangular tuning stub. The antenna is fabricated onto an inexpensive FR4 substrate with an overall dimension of 22 × 24 mm2. The experiment shows that the proposed antenna achieves good impedance matching constant gain, stable radiation patterns over an operating bandwidth of 3-11.2 GHz (115.5%) that covers the entire UWB. The nearly stable radiation pattern with a maximum gain of 5.4 dBi makes the proposed antenna suitable for being used in UWB communication applications.

Implementation of a Cognitive Radio Front-End Using Rotatable Controlled Reconfigurable Antennas

Abstract: This communication presents a new antenna system designed for cognitive radio applications. The antenna structure consists of a UWB antenna and a frequency reconfigurable antenna system. The UWB antenna scans the channel to discover “white space” frequency bands while tuning the reconfigurable section to communicate within these bands. The frequency agility is achieved via a rotational motion of the antenna patch. The rotation is controlled by a stepper motor mounted on the back of the antenna structure. The motor's rotational motion is controlled by LABVIEW on a computer connected to the motor through its parallel port. The computer's parallel port is connected to a NPN Darlington array that is used to drive the stepper motor. The antenna has been simulated with the driving motor being taken into consideration. A good agreement is found between the simulated and the measured antenna radiation properties.

Compact Circularly-Polarized Patch Antenna Loaded With Metamaterial Structures

Abstract: A metamaterial-inspired low-profile patch antenna is proposed and studied for circularly-polarized (CP) radiation. The present antenna, which has a single-fed configuration, is loaded with the composite right/left-handed (CRLH) mushroom-like structures and a reactive impedance surface (RIS) for miniaturization purpose. The CP radiation is realized by exciting two orthogonally-polarized modes simultaneously which are located in the left-handed (LH) region. The detailed antenna radiation characteristics are examined and illustrated with both simulated and experimental results. The CP performance can be controlled in several different ways. This antenna exhibits an overall size of 0.177λ0 × 0.181λ0 × 0.025λ0 at 2.58 GHz and a radiation efficiency around 72%. Finally, based on the proposed CP patch antenna, a compact dual-band dual linearly-polarized patch antenna has also been designed and fabricated. Promising experimental results are observed.

A New Compact Filter-Antenna for Modern Wireless Communication Systems

Abstract: Design, fabrication, and measurement of a new compact filter-antenna for modern wireless communication systems are presented in this letter. Two microstrip square open-loop resonators, a coupled line, and a Γ-shaped antenna are used and integrated to be a filter-antenna. The Γ-shaped antenna is excited by a coupled line that is treated as the admittance inverter in filter design. The Γ-shaped antenna performs not only a radiator, but also the last resonator of the bandpass filter. Therefore, near-zero transition loss is achieved between the filter and the antenna. The design procedure follows the circuit approach-synthesis of bandpass filters. Measured results show that the filter-antenna achieves an impedance bandwidth of 16.3% (over 2.26-2.66 GHz) at a reflection coefficient |S11 | <; - 10 dB and has a gain of 2.41 dBi.

Design of an Implantable Slot Dipole Conformal Flexible Antenna for Biomedical Applications

Abstract: We present a flexible folded slot dipole implantable antenna operating in the Industrial, Scientific, and Medical (ISM) band (2.4-2.4835 GHz) for biomedical applications. To make the designed antenna suitable for implantation, it is embedded in biocompatible Polydimethylsiloxane (PDMS). The antenna was tested by immersing it in a phantom liquid, imitating the electrical properties of the human muscle tissue. A study of the sensitivity of the antenna performance as a function of the dielectric parameters of the environment in which it is immersed was performed. Simulations and measurements in planar and bent state demonstrate that the antenna covers the complete ISM band. In addition, Specific Absorption Rate (SAR) measurements indicate that the antenna meets the required safety regulations.

Compact Triband Square-Slot Antenna With Symmetrical L-Strips for WLAN/WiMAX Applications

Abstract: A novel triband square-slot antenna with symmetrical L-strips is presented for WLAN and WiMAX applications. The proposed antenna is composed of a square slot, a pair of L-strips, and a monopole radiator. By employing these structures, the antenna can yield three different resonances to cover the desired bands while maintaining small size and simple structure. Based on this concept, a prototype of a triband antenna is designed, fabricated, and tested. The experimental results show the antenna has the impedance bandwidths of 480 MHz (2.34-2.82 GHz), 900 MHz (3.16-4.06 GHz), and 680 MHz (4.69-5.37 GHz), which can cover both WLAN in the 2.4/5.2-GHz bands and WiMAX in the 2.5/3.5-GHz bands.

Single-Fed Broadband Circularly Polarized Stacked Patch Antenna With Horizontally Meandered Strip for Universal UHF RFID Applications

Abstract: In this paper, a horizontally meandered strip (HMS) feed technique is proposed to achieve good impedance matching and symmetrical broadside radiation patterns for a single-fed broadband circularly polarized stacked patch antenna, which is suitable for universal ultrahigh frequency (UHF) RF identification (RFID) applications. The antenna is composed of two corner truncated patches and an HMS, all of which are printed on the upper side of the FR4 substrates. One end of the HMS is connected to the main patch by a probe, while the other end is connected to an SMA connector. Simulation results are compared with the measurements, and a good agreement is obtained. The measurements show that the antenna has an impedance bandwidth (VSWR <; 1.5) of about 25.8% (758-983 MHz), a 3-dB axial ratio (AR) bandwidth of about 13.5% (838-959 MHz), and a gain level of about 8.6 dBic or larger within the 3-dB AR bandwidth. Therefore, the proposed antenna can be a good candidate for universal UHF RFID readers operating at the UHF band of 840-955 MHz. In addition, a parametric study and a design guideline of the proposed antenna are presented to provide the engineers with information for designing, modifying, and optimizing such an antenna. At last, the proposed antenna is validated in RFID system applications.

Miniaturized UWB Monopole Microstrip Antenna Design by the Combination of Giusepe Peano and Sierpinski Carpet Fractals

Abstract: A fractal monopole antenna is proposed for the application in the UWB frequency range, which is designed by the combination of two fractal geometries. The first iterations of Giusepe Peano fractal are applied on the edges of a square patch, and a Sierpinski Carpet fractal is formed on its surface. The feed circuit is a microstrip line with a matching section over a semi-elliptical ground plane. The presented antenna has an omnidirectional radiation pattern, a good gain, and high efficiency. The fabrication and measurement data attest to the satisfaction of the design specifications.

UWB Band-Notched Monopole Antenna Design Using Electromagnetic-Bandgap Structures

Abstract: A new approach is proposed to reject certain bands within the passband of an ultra-wideband planar monopole antenna. The proposed approach that utilizes a mushroom-type electromagnetic-bandgap (EBG) structure is proven to be an effective way for band-notched designs. The approach has many advantages, such as notch-frequency tunability, notch-band width controllable capacity, efficient dual-notch design, and stable radiation patterns. Several design examples using conventional mushroom-type EBG and edge-located vias mushroom-type EBG are presented. The examples exhibit good bandstop characteristics to reject the wireless local-area network interference bands (5.2- and 5.8-GHz bands). Besides, the causes that lead to the discrepancies between the simulations and measurements are discussed.

A Compact Filtering Microstrip Antenna With Quasi-Elliptic Broadside Antenna Gain Response

Abstract: Design, fabrication, and measurement of a compact filtering microstrip antenna with second-order quasi-elliptic broadside antenna gain response are presented. A U-shape radiating patch is excited by a T-shape resonator through an inset coupling structure. The U-shape patch acts as a radiator as well as the last stage of the filter, and the inset coupling structure can be treated as the admittance inverter in filter design. The design procedure follows the circuit approach-synthesis of bandpass filters. The broadside gain of the filtering antenna has two poles in passband and two broadside radiation nulls (zeros) at the band edges for improving selectivity. Compared to the conventional inset-fed microstrip antenna, with a little extra circuit area, the proposed filtering antenna has a flatter passband response, better frequency skirt selectivity, and almost twice wider bandwidth. The measurement result shows a good agreement with the simulations.

Antenna with integrated proximity sensor for proximity-based radio-frequency power control

Abstract: An electronic device may have a housing in which an antenna is mounted. An antenna window may be mounted in the housing to allow radio-frequency signals to be transmitted from the antenna and to allow the antenna to receive radio-frequency signals. Near-field radiation limits may be satisfied by reducing transmit power when an external object is detected in the vicinity of the dielectric antenna window and the antenna. A capacitive proximity sensor may be used in detecting external objects in the vicinity of the antenna. The proximity sensor and the antenna may be formed using integral antenna resonating element and proximity sensor capacitor electrode structures. These structures may be formed from identical first and second patterned conductive layers on opposing sides of a dielectric substrate. A transceiver and proximity sensor may be coupled to the structures through respective high-pass and low-pass circuits.

Millimeter wave radio assembly with a compact antenna

Abstract: An integrated compact antenna device and method of aiming an electromagnetic signal using the integrated compact antenna device are described. The integrated compact antenna device be a vertically mounted cylinder enclosing an antenna, some electronic circuitry and most of the directional alignment mechanism. During alignment, the cylinder of the ICA rotates to provide azimuth. The cylinder is attached to a fixed base that remains stationary relative to the mounting structure.

A Compact Monopole Antenna for Super Wideband Applications

Abstract: A planar microstrip-fed super wideband monopole antenna is initially proposed. By embedding a semielliptically fractal-complementary slot into the asymmetrical ground plane, a 10-dB bandwidth of 172% (1.44-18.8 GHz) is achieved with ratio bandwidth >;12:1. Furthermore, the proposed antenna also demonstrated a wide 14-dB bandwidth from 5.4 to 12.5 GHz, which is suitable for UWB outdoor propagation. This proposed antenna is able to cover the DVB-H in L-band (for PMP), DCS, PCS, UMTS, Bluetooth, WiMAX2500, LTE2600, and UWB bands.

Dual band electrically small tunable antenna

Abstract: An electrically small dual-band planar tunable UHF/L-Band antenna In one example, the dual-band antenna includes a combination of a semi-spiral antenna for the UHF frequencies and a microstrip patch antenna for the L-band frequencies

Multioctave Frequency Selective Surface Reflector for Ultrawideband Antennas

Abstract: In this letter, we demonstrate the gain enhancement of an ultrawideband (UWB) antenna, achieved using an appropriately designed multioctave dual-layer frequency selective surface (FSS) reflector. The proposed novel FSS reflects effectively in phase over a bandwidth of about 120%. Hence, significant enhancement in antenna gain has been achieved with a low-profile configuration without compromising the impedance bandwidth of the UWB antenna. The proposed FSS reflector has a low transmission coefficient and linearly decreasing phase over an ultra-wide frequency band, which is the key requirement for providing an effectively in-phase reflection at the antenna plane. The composite structure is compact, with a total height of λ/4, where λ is the free-space wavelength at the lowest operating frequency of 3 GHz. Experimental results show an impedance bandwidth of 122%. The antenna gain is maintained around 7.5 dBi from 3 to 7 GHz. Between 7-14 GHz, the antenna is more directive with a gain of about 9 dBi with ±0.5 dB variation. Experimental measurements con firm the predicted wideband antenna performance and gain enhancement due to the FSS reflector.

A Compact Dual-Band Fork-Shaped Monopole Antenna for Bluetooth and UWB Applications

Abstract: A simple, low-cost, and compact printed dual-band fork-shaped monopole antenna for Bluetooth and ultrawideband (UWB) applications is proposed. Dual-band operation covering 2.4-2.484 GHz (Bluetooth) and 3.1-10.6 GHz (UWB) frequency bands are obtained by using a fork-shaped radiating patch and a rectangular ground patch. The proposed antenna is fed by a 50-Ω microstrip line and fabricated on a low-cost FR4 substrate having dimensions 42 (Lsub) × 24 (Wsub) × 1.6 (H) mm3. The antenna structure is fabricated and tested. Measured S11 is ≤ -10 dB over 2.3-2.5 and 3.1-12 GHz. The antenna shows acceptable gain flatness with nearly omnidirectional radiation patterns over both Bluetooth and UWB bands.

Dynamically adjustable antenna supporting multiple antenna modes

Abstract: Electronic devices (10) such as cellular phones include radio-frequency transceiver circuitry coupled to an adjustable antenna (40). The adjustable antenna contains conductive antenna structures such as conductive electronic device housing structures (17-1). Electrical components (42-1,42-2,42-3,42-4) such as switches and resonant circuits are used in configuring the antenna to operate in two or more different antenna modes at different respective communications bands. Control circuitry may be used in controlling the switches. The antenna may be configured to operate as an inverted-F antenna in one mode of operation and a slot antenna in a second mode of operation.

A Slot-Monopole Antenna for Dual-Band WLAN Applications

Abstract: A coplanar waveguide (CPW)-fed antenna consisting of slot and monopole antenna for dual-band design is proposed. The proposed antenna can provide two separate impedance bandwidths of 124 MHz (about 5.1% centered at 2.45 GHz) and 1124 MHz (about 22.4% centered at 5.5 GHz), making it easy to cover the specification for WLAN operation in the 2.45-GHz band (about 3.4% required bandwidth) and 5.2/5.8-GHz bands (about 13% required bandwidth). Furthermore, the proposed antenna has a low profile of 3.5 mm, making it suitable for installation in wireless handheld devices. Details of the proposed antenna design and experimental results are presented and discussed.

Omni-directional antenna system for wireless communication

Abstract: A wireless device having an improved antenna system is disclosed comprising one or more antenna, preferably circularly polarized antenna, for transmitting or receiving a signal, and one or more floating ground planes, wherein the floating ground plane preferably is electrically isolated from and in sufficient proximity to the antenna so that it is inductively coupled to the antenna. The floating ground plane may comprise one or more of a strip, band, foil, plate, block, wire mesh, sheet or coating of conductive material and, for example, may be a relatively thin copper strip, band, foil or coating. The circularly polarized antenna, preferably comprises a flat planar shaped radiating element sized and configured to resonate at a predetermined, desired frequency, frequencies or band of frequencies, and a flat planar shaped antenna ground, both radiating element and antenna ground formed on the same printed circuit board. The radiating element is electrically isolated from the antenna ground but sufficiently close to resonate at the desired frequencies. Preferably the floating ground plane is larger than or more massive than the antenna ground, and preferably larger than or more massive than the radiating element. In a further embodiment the wireless device comprises a housing for interfacing with a user, the housing comprising a conductive contact exposed to the exterior of the housing and configured to be contacted by a user, wherein the conductive contact is electrically connected to the floating ground plane, preferably so that the user is coupled to the antenna and becomes part of the antenna system. The floating ground plane may also preferably be configured to substantially cover or overlap the antenna, and may also be configured to distribute and propagate the electromagnetic signals away from the head of the user.

Configurable Antenna Assembly

Abstract: A configurable antenna assembly includes an antenna structure and a configurable antenna interface. The antenna structure is operable, in a first mode, to provide a first antenna structure and a second antenna structure, wherein the first antenna structure receives an inbound radio frequency (RF) signal and the second antenna structure transmits an outbound RF signal. The configurable antenna interface is operable in the first mode to provide a first antenna interface and a second antenna interface, wherein the first antenna interface is configured in accordance with a receive adjust signal to adjust at least one of phase and amplitude of the inbound RF signal, and wherein the second antenna interface is configured in accordance with a transmit adjust signal to adjust at least one of phase and amplitude of the outbound RF signal.

Design of a Band-Notched UWB Monopole Antenna by Means of an EBG Structure

Abstract: In this letter, a new compact ultra wideband circular monopole antenna with an acceptable band-rejection characteristic is investigated. This rejection band is created by means of an electromagnetic band-gap (EBG) structure. The EBG structure that is used here is a mushroom-like structure. An equivalent circuit model is employed to investigate the stopband characteristic of the EBG. The operation frequency band is 3.1-10.6 GHz with a rejection band of 0.7 GHz around 5.5 GHz. Accurate and high rejection is achieved. The proposed model is implemented, and the measured results are in good agreement with simulated ones.

Small Square Monopole Antenna With Enhanced Bandwidth by Using Inverted T-Shaped Slot and Conductor-Backed Plane

Abstract: We present a novel printed monopole antenna for ultra wideband applications. The proposed antenna consists of a square radiating patch with an inverted T-shaped slot and a ground plane with an inverted T-shaped conductor-backed plane, which provides a wide usable fractional bandwidth of more than 130% (2.91-14.1 GHz). By cutting a modified inverted T-shaped slot with variable dimensions on the radiating patch and also by inserting an inverted T-shaped conductor-backed plane, additional resonances are excited and hence much wider impedance bandwidth can be produced, especially at the higher band. The designed antenna has a small size of 12 × 18 mm2 . Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range.

On the Use of U-Slots in the Design of Dual-and Triple-Band Patch Antennas

Abstract: The general method of using U-slots to design dual- and triple-band patch antennas is described. In this approach, one starts with a broadband patch antenna, which can consist of one or more patches. When a U-slot is cut in one of the patches, a notch is introduced into the matching band, and the antenna becomes a dual-band antenna. If another U-slot is cut in the same patch or in another patch, a triple-band antenna results. This method is applied to the L-probe-fed patch, the M-probe-fed patch, as well as the coaxially fed and aperture-coupled stacked patches. It is found that the patterns and gains of the dual-and triple-band antennas are similar to those of the original broadband antenna. Because the band notches introduced by the U-slots occur within the bandwidth of the antenna without slots, this method is suitable when the frequency ratios of the adjacent bands are small, usually less than 1.5.

Investigation Into the Application of Artificial Magnetic Conductors to Bandwidth Broadening, Gain Enhancement and Beam Shaping of Low Profile and Conventional Monopole Antennas

Abstract: The reflection coefficient phase is investigated for several different artificial magnetic conductors (AMCs) having canonical FSS-type shapes. Three of them are selected, each representing a different class, and fine tuned to exhibit identical resonant frequency. Polarization and angular dependence as well as the effects of losses on these structures are studied. Next, a low-profile inverted L-shape monopole antenna (ILSMA) is placed horizontally above the ground plane. Vertical monopole antenna (VMA) is also placed above them. It is shown that using some of the aforementioned AMCs, the input impedance of both ILSMA and VMA can not only be matched, but also the input impedance bandwidth enhancement as wide as 27% and 35% are obtained, respectively. The VMA study on AMC ground planes which reveals a counter-intuitive phenomenon has not been explored in the literature, previously. It is revealed that the broadband characteristics can also be achieved for smaller size of the AMC ground planes, which enables the antenna to be designed in compact size. It is also illustrated that reflection characteristics of the AMC is not sufficient to evaluate AMC performance when it is used as an antenna ground plane. This is illustrated through extensive simulation and measurement results.

Low-profile multiband antenna for a wireless communication device

Abstract: A device for wireless communication including a wireless transceiver, a printed circuit board (PCB) coupled to the wireless transceiver, a first antenna and a second antenna. The first antenna is coupled to the PCB at a feed point and grounded at a ground point. The first antenna is a quarter-wavelength antenna communicating signals with the wireless transceiver at a first frequency band. The second antenna is coupled to the first antenna at the feed point and grounded at a further ground point. The second antenna is a half-wavelength antenna communicating signals with the wireless transceiver at a second frequency band.

Optimized Microstrip Antenna Arrays for Emerging Millimeter-Wave Wireless Applications

Abstract: Two compact planar antennas operating in the unlicensed 60 GHz frequency band are presented based on the physical layer specifications of IEEE 802.15.3c and ECMA 387 standards for different classes of wireless applications. Each antenna is an array of 2 × 2 microstrip antennas covering at least two channels of the 60 GHz spectrum. The first antenna is optimized to achieve the highest gain, while the second antenna is optimized to give the largest beamwidth. The maximum measured radiation gain of the first antenna is 13.2 dBi. The measured beamwidth and gain of the second antenna are 76° and 10.3 dBi, respectively. The areas of these two antenna are only 0.25 and 0.16 cm2. The variation of radiation gain of each antenna over the frequency range of 57-65 GHz is less than 1 dB.

Three-dimensional antenna structure

Abstract: A three-dimensional antenna structure includes first and second antenna components and a via. The first antenna component is on a first layer of a substrate and the second antenna component is on a second layer of a substrate. The via couples the first antenna component to the second antenna component, wherein the first antenna overlaps, from a radial perspective, the second antenna component by an angle of overlap.

System and method for locating mobile devices

Abstract: A system includes a three dimensional antenna and mobile devices that wirelessly communicate with the antenna. A phase of arrival and a phase difference of arrival are calculated, and a distance between the three dimensional antenna and the mobile device is calculated. A direction between the three dimensional antenna and the mobile device is calculated. The direction calculation includes an angular spread function of multipath scattering in the communication between the three dimensional antenna and the mobile device. The direction calculation further includes an estimation of a propagation delay and an angle in the communication between the three dimensional antenna and the mobile device.