Showing papers on "Folded inverted conformal antenna published in 2003"

Impedance, bandwidth, and Q of antennas

Abstract: The purpose of this paper is twofold: (1) to derive an approximate expression for the bandwidth of a tuned antenna in terms of its input impedance that holds at every frequency, i.e., throughout its entire antiresonant and resonant frequency ranges; (2) to relate this expression for bandwidth to the antenna quality factor Q. The approximate expression for the bandwidth and its relationship to Q are both more generally applicable and more accurate than previous formulas. The validity and accuracy of the expressions are confirmed by the numerical solutions to straight-wire and wire-loop, lossy and lossless tuned antennas over a wide enough range of frequencies covering several resonant and antiresonant frequency bands. We show that the matched VSWR bandwidth is a more fundamental measure of bandwidth than conductance bandwidth because it exists in general for all frequencies at which an antenna is tuned. We also find that the Foster reactance theorem does not hold at all frequencies (whether or not the antenna is lossless). Although the general formula we derive for the bandwidth of an antenna involves the frequency derivative of resistance as well as the frequency derivative of reactance, quite remarkably, the half-power matched VSWR bandwidth of a general tuned lossy or lossless antenna is proven to approximately equal to 2/Q for all frequencies if Q/spl gsim/4.

A low-profile planar monopole antenna for multiband operation of mobile handsets

Abstract: A novel planar monopole antenna is proposed. It has a very low profile (antenna height less than 0.04 times the operating wavelength in free space) and is capable of multiband operation. The proposed antenna has a planar rectangular radiating patch in which a folded slit is inserted at the patch's bottom edge. The folded slit separates the rectangular patch into two subpatches, one smaller inner subpatch encircled by the larger outer one. The proposed antenna is then operated with the inner subpatch resonating as a quarter-wavelength structure and the outer one resonating as both a quarter-wavelength and a half-wavelength structure. The proposed antenna, 12 mm high and 30 mm wide, has been constructed, and the obtained bandwidths cover the global system for mobile communication (890-960 MHz), digital communication system (1710-1880 MHz), personal communication system (1850-1990 MHz), and universal mobile telecommunication system (1920-2170 MHz) bands. Details of the proposed design and obtained experimental results are presented and discussed.

A broad-band dual-polarized microstrip patch antenna with aperture coupling

Abstract: In this communication, a dual-polarized aperture-coupled microstrip patch antenna with a broad-bandwidth high-isolation low cross-polarization levels, and low-backward radiation levels is designed and its features are presented. For broad bandwidth and easy integration with active circuits, it uses the aperture-coupled stacked patches. The corner feeding of square microstrip patches is applied and the coupling aperture is the H-shaped aperture. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. A dual-polarized antenna is designed, fabricated, and measured. The measured return loss exhibits an impedance bandwidth of over 24.4% and the isolation is better than 30 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than -23 dB. The front-to-back ratio of the antenna radiation pattern is better than 22 dB. Both theoretical and experimental results for S parameters and radiation patterns are presented and discussed.

Dual-polarized slot-coupled planar antenna with wide bandwidth

Abstract: A new dual-polarized slot-coupled microstrip patch antenna is presented, which can achieve high-isolation, low cross-polarization levels, a wide bandwidth, and low backward radiation levels. The coupling slot is an H-shaped slot. For wide bandwidth and easy integration with active circuits, it uses slot-coupled stacked microstrip patches. The theoretical analysis is based on the finite-difference time-domain (FDTD) method. First, a parametric study on the input impedance of the antenna with a single input port is presented. Based on the results, a dual-polarized microstrip antenna is designed, fabricated, and then measured. The measured return loss exhibits an impedance bandwidth of over 20.9% and the isolation between two polarization ports is better than 36 dB over the bandwidth. The cross-polarization levels in both E and H planes are better than 22 dB. The front-to-back ratio of the antenna radiation pattern is better than 21 dB. Both theoretical and experimental results of return loss, isolation, and radiation patterns are presented and discussed.

Planar antenna with supplemental antenna current configuration arranged between dominant current paths

Abstract: An antenna arrangement is described in which a pair of at least generally planar opposing antenna arms each support a first high frequency antenna current responsive to an input Each arm includes a peripheral outline for confining the first high frequency current to a pair of first and second dominant paths, that are defined by the peripheral outline, in a spaced apart relationship across each of the opposing antenna arms so as to define an isolated area between the first and second paths A configuration is located in this area of at least one of the antenna arms for producing an additional high frequency current responsive to the input The additional high frequency current cooperates with the first high frequency antenna current to produce an overall antenna response In one feature, the opposing antenna arms are bow arms which cooperate to define an overall bow-tie configuration as the peripheral outline

Wearable microstrip antenna

Abstract: Microstrip antennas are being used as a representative antenna for mobile and satellite communication The microstrip antennas have features such as planarity and a relatively high gain (about 7 dBi) It is typical to fabricate them by using hard substrates However, these substrates are limited in shape and mounting placement for fixing such an antenna to clothing or hats Therefore, we created a flexible and light-weight antenna The antenna we built is composed of a flexible woven conductive fabric and felt Because of the construction, it can be easily sewn into clothing or hats It can be applied as a GPS antenna for monitoring the position of wandering aged, or as a terminal antenna for personal satellite communications In this paper, the structure of the antenna is described, and its characteristics are evaluated

On the lower bound of the radiation Q for electrically small antennas

Abstract: The fundamental question of the lower bound on the radiation Q of an electrically small antenna is of practical importance because of its relationship to the antenna bandwidth. Previous works predict a lower bound on the radiation Q that is usually too low and, hence, a bandwidth that can be optimistically large. This paper addresses why this is so and offers a new prediction for a realizable lower bound on the radiation Q. This new prediction is based on the far-field pattern, in both the visible and invisible spatial regions, in contrast to previous works based upon a near-field modal approach. Results for a linear dipole, bow-tie, and end-loaded dipole are presented to illustrate the validity of the lower bound presented herein. Radiation Q can be related to bandwidth provided the Q is adequately large. Implicit is the presence of a matching network as a part of the antenna system. Both the losses in the antenna and the losses in the matching network have an effect on the system bandwidth, the system efficiency and the system Q, of which the radiation Q is a part. These various relationships are also discussed.

Dual-band planar inverted F antenna for GSM/DCS mobile phones

Abstract: A compact dual-band planar inverted F antenna suitable for the application as a global system for mobile communication/digital communication system (GSM/DCS) dual-band mobile phone internal antenna is proposed and implemented. The proposed antenna has three resonant elements, two meandered metallic strips of slightly different lengths and one nearly-rectangular patch, which are printed on a supporting FR4 substrate and arranged in a compact configuration. These three resonant elements share a common shorting pin, and for the GSM (890-960 MHz) operation, the proposed antenna is operated with the two meandered strips both resonated as a quarter-wavelength structure, leading to a wide bandwidth formed by two resonant modes. For the upper band of the proposed antenna, three resonant modes are generated, two from the second higher-order modes of the two meandered strips and one from the nearly-rectangular patch, leading to a wide bandwidth covering the DCS band (1710-1880 MHz). The antenna design and experimental results are presented.

Micromachined reconfigurable out-of-plane microstrip patch antenna using plastic deformation magnetic actuation

Abstract: A new reconfigurable out-of-plane microstrip patch antenna is presented. Using micromachining processes, a microstrip antenna designed for operation around 26 GHz is covered with a thin layer of magnetic material and released from the substrate. Application of an external DC magnetic field causes plastic deformation of the antenna at the boundary point where it is attached to the microstrip feed line, resulting in a patch positioned at an angle over the substrate. Frequency and pattern reconfigurability are demonstrated with measurements. Results indicate that versions of this structure may be used to expand or enhance the capabilities of traditional planar arrays.

Resonant frequency of circular microstrip antenna covered with dielectric superstrate

Abstract: A simple design formulation to compute accurate resonant frequencies of circular microstrip antennas covered with dielectric superstrates is proposed. It alleviates the rigorous mathematical analyzes and large computational time of some earlier works. This theory is widely applicable to both high and low dielectric constant superstrates as verified with the experiments and other theoretical models. Of all theories, the present one shows the closest approximation with the measurements revealing average percent error as low as 0.52%. The extension of this formulation to predict the accurate design data for conventional microstrip circular antennas are also verified with different experiments and available improved theories for various sets of antenna parameters.

PIFA with a meandered and folded patch for the dual-band mobile phone application

Abstract: In this communication, a novel design of the planar inverted-F antenna (PIFA) is proposed for the dual-band mobile telephone application. To reduce the antenna size, the radiating patch is meandered and folded. The studies begin with a folded-patch PIFA that has two tunable resonant modes. Next, by loading three slits on the patch, the surface current path is meandered and the antenna length is reduced significantly. The IE3D simulation software is employed for optimizing the design parameters, and the simulation results in general agree with the measured data. Results also show that, the excitation of the 900 and 1800 MHz resonant modes can be achieved for the proposed antenna with a small volume of 24/spl times/10/spl times/7.2 mm/sup 3/. Radiation patterns for both resonances are measured and shown. The maximum antenna gain is estimated to be 2.5 dBi for both 900/1800 band operations.

Compact internal multiband antennas for mobile handsets

Abstract: A novel compact internal quad-band handset antenna for covering the GSM900, DCS1800, PCS1900, and ISM2450 bands is presented. The proposed antenna consists of folded patches sharing a common shorting strip and occupies a total volume of 36/spl times/16/spl times/9 mm/sup 3/. Details of the antenna are discussed along with measured and simulation results. The simulation is based on the finite-difference time-domain method.

A single-feeding circularly polarized microstrip antenna with the effect of hybrid feeding

Abstract: A single series feed cross-aperture coupled microstrip antenna with the effect of hybrid feeding is proposed and demonstrated. To understand this antenna better, the characteristics according to the variation of parameters are shown. This proposed antenna has the following advantages of the effect of hybrid feeding: improved axial ratio bandwidth (4.6%); high gain (8 dBi); flat 3 dB gain bandwidth (above 16.7%). In measured radiation patterns, we have 3 dB beamwidth of /spl plusmn/30/spl deg/ and good F/B (front to back ratio) of 20 dB.

Planar inverted f antennas including current nulls between feed and ground couplings and related communications devices

Abstract: A planar inverted F antenna may be configured for operation at an operating frequency band, and the planar inverted F antenna may include first (103), second (105), and third (107) antenna segments, a reference voltage coupling (108), and a feed coupling (109). The first and second antenna segments may be separated by at least approximately 3 mm, and the third antenna segment may couple the first and second antenna segments. The reference voltage and feed couplings may both be provided on the first antenna segment, and a current null may be present between the feed and reference voltage couplings at the operating frequency band. Related communications devices are also discussed.

Compact antenna structures for mobile handsets

Abstract: In this paper, novel compact antenna structures for mobile handsets are studied. The antennas are based on non-resonant coupling elements, which are used to optimally couple to the characteristic wavemodes of the chassis. The resonances for the antenna structures are created with matching circuits. Two different antenna models are designed based on the novel antenna structure. From each model, single-band prototypes for the E-GSM900 and GSM1800 systems are constructed. The volume of the smaller antenna model is only 1.3 cm/sup 3/. Both models meet the bandwidth and SAR requirements of the E-GSM900 and GSM1800 systems. Efficiencies are high and the radiation patterns are suitable for use in mobile handsets. The measurement results of the constructed prototypes suggest that the compact antenna structure studied in this paper has great potential for use in mobile handsets.

An internal triple-band planar inverted-F antenna

Abstract: A novel internal triple-band planar inverted-F antenna (PIFA) for operating at Personal Communication Services/International Mobile Telecommunications (PCS/IMT)-2000/Bluetooth bands is proposed. The proposed antenna can be reduced in size by using a radiating element with thickness and a via hole. A broadband characteristic is obtained by optimizing the thickness of the radiating patch and the offset gap between patch and ground. Dual resonant frequencies are obtained by optimizing the slit lengths and the location of the via hole. The proposed antenna is well suited as an internal antenna due to its small size and wide bandwidth, of about 42%, which covers the PCS (1.75-1.87 GHz), IMT-2000 (1.92-2.17 GHz) and Bluetooth (2.402-2.48 GHz) bands. The design of the proposed antenna and experimental results are discussed.

Dual-band reduced size PIFA antenna with U-slot for Bluetooth and WLAN applications

Abstract: A dual-band internal planar inverted-F antenna (PIFA) is proposed for 2.4 GHz Bluetooth (ISM) and wireless area network (WLAN) 5.2 GHz (IEEE 802.116) applications. The antenna has a rigid design with a foam substrate so it can be integrated easily with the Bluetooth housing of personal digital assistant (PDA) devices. A U-shaped slot is etched in the top plate to achieve the dual-band operation. The antenna has a single feed with total compact size of 14/spl times/15/spl times/6 mm/sup 3/. The antenna bandwidth is 4% and 4.3% at the lower and upper frequencies, respectively.

On the behavior of the Koch island fractal boundary microstrip patch antenna

Abstract: The properties of the Koch island fractal boundary microstrip patch antenna are presented. The behavior at the fundamental mode and the existence of high-order modes that exhibit localized current density distributions is discussed. The main features are the size reduction of the patch resonating at the fundamental frequency when compared to Euclidean-shaped patches, and the application of localized modes in designing microstrip patch antennas with directive patterns.

Shorted, folded planar monopole antenna for dual-band mobile phone

Abstract: A novel shorted, folded planar monopole antenna for application in GSM/DCS dual-band mobile phones is proposed. The antenna is easily fabricated from stamping a single metal plate, which is then folded onto a foam base of compact size 5×10×40 mm3. In addition, the proposed antenna shows a very low profile of 5 mm protruded from the top edge of the system ground plane, making it very promising to be employed within the casing of a mobile phone as an internal antenna.

Miniaturisation of microstrip patch antenna using perturbation of radiating slot

Abstract: A highly miniaturised rectangular microstrip patch antenna using deformation of the patch structure has been designed and fabricated at a frequency of 1.575 GHz (GPS). The fabricated antenna has a patch with an overall rectangular shape and depressed at its four corners (corner depressed microstrip patch antenna, CDMPA). In the linear polarisation, at a fixed rate of 1.2 of width/length (W/L), the CDMPA (53×63.6 mm) is reduced to 43.9% of the general plane type microstrip patch antenna (MPA, 80×96 mm) in patch size. The gain is 4.3 dBd which is lower than that of the general MPA (8 dBd) by 3.7 dB. In the circular polarisation, the patch size of the CDMPA (54.2×61.5 mm) is reduced to 52.8% of that of the MPA (76×83 mm). The axial ratio (AR) and axial ratio band width (ARBW) within 2 dB are 1.5 dB and 20 MHz (1.27%), respectively. The gain is 2.5 dBd, which is lower than that (4.2 dBd) of the general MPA by 1.7 dB.

Effect of ground plane size on the free-space performance of a mobile handset PIFA antenna

Abstract: In this paper the free-space performance of a commonly used planar inverted-F antenna (PIFA) on top of various rectangular ground planes is studied by simulations. Special attention is given to impedance bandwidth and antenna efficiency. The study is carried out for five frequency bands; CDMA800, GSM900, GSM1800, GSM1900 and UMTS. Optimal ground plane dimensions for each frequency band are given and performance results for selected bands are shown as a function of the ground plane dimensions. Finally effect of the ground plane size on the performances of multiband antennas comprised of different combinations of selected frequency bands are discussed.

Analysis of circular microstrip patch antenna as an equivalent rectangular microstrip patch antenna on iso/anisotropic thick substrate

Abstract: The input and radiation characteristics of a circular microstrip antenna on thick and lossy iso/anisotropic substrate are computed with the help of its equivalent rectangular microstrip antenna. The computed results show good agreement with the results of mode matching methods and experimental results. Results using three commercial software products are also compared against the same set of the experimental results. The performance of the present method (MWM) is better than the performance of commercial software.

Miniaturized reverse-fed planar inverted f antenna

Abstract: In a planar inverted F antenna (PIFA) (200), the feed (206)and RF grounding (208) connections are reversed yielding improved performance. Relative positioning of these connections is selected to tailor the characteristics of the antenna, such as resonant frequency and impedance bandwidth.

A triband antenna for WLAN applications

Abstract: The design and analysis of a new triband antenna have been presented. The antenna is suitable for use in hand-held or other mobile devices and offers advantages in size, cost, and performance. The antenna can be built on a double-sided printed circuit board (PCB) or stamped from thin sheet metal. The antenna can also be built as an on-board antenna to reduce the manufacturing cost. The antenna design is patent pending.

Three-element stacked microstrip antenna with wide-band and high-gain performances

Abstract: In this paper, the three-element stacked microstrip antenna which is composed of a fed element and two parasitic elements is proposed. It has a wide bandwidth and a high gain. The stacked microstrip antenna is precisely analyzed using the FDTD method, in order to investigate the characteristics and the behavior mechanism of the stacked antenna.

Miniature broadband ring-like microstrip patch antenna

Abstract: A miniature broadband stacked microstrip patch antenna formed by two patches, an active and a parasitic patches, where at least one of them is defined by a Ring-Like Space-Filling Surface (RSFS) being this RSFS newly defined in the present invention. By means of this novel technique, the size of the antenna can be reduced with respect to prior art, or alternatively, given a fixed size the antenna can operate at a lower frequency with respect to a conventional microstrip patch antenna of the same size and with and enhanced bandwidth. Also, the antennas feature a high-gain when operated at a high order mode.

Single-layer single-feed dual-frequency circular microstrip antenna with an offset open-ring slot

Abstract: A novel dual-frequency design of a single-layer single-feed circular microstrip antenna with an offset open-ring slot is demonstrated. For the proposed design, an offset open-ring slot is embedded in the circular patch. By selecting a suitable radius of the circular patch enclosed by this offset open-ring slot, a dual-frequency operation with its two operating modes excited with the same polarization planes is obtained. The frequency ratio of the two frequencies is within a range of about 1.22 to 2.17. The measured results show that similar broadside radiation patterns are obtained and the variations of antenna gain are small for frequencies within the two resonant modes. Details of the antenna design and the experimental results obtained for the dual-frequency performance are presented.

Dual-band planar inverted F antenna for laptop computers

Abstract: This paper describes the analysis and design of a dual-band planar inverted F antenna for laptop computers. This antenna has desirable characteristics for use in IEEE802.11b and IEEE802.11a wireless LAN. The computed results (required gain, input characteristics and far-field pattern) are given. The dual-band planar inverted F antenna, mounted in a laptop computer has been demonstrated to operate in the 2.4 GHz and 5.2 GHz bands with |S/sub 11/| less than -9.5 dB.

Dual-band planar inverted-F antenna

Abstract: A new kind of planar inverted F antenna (PIFA) is presented. To reduce the size of the structure, the resonator has been curled under itself. A capacitive load is added to decrease the frequencies of higher resonances. The result is the achievement of a dual-band antenna. Theoretical results are computed by the software design package IE3D. The effects of various physical parameters are presented and discussed. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 40–42, 2003

Center-fed microstrip patch antenna

Abstract: A novel feeding scheme for microstrip patch antennas is presented, which consists of a coaxial probe and shorting pin separated by a narrow slot centrally cut at the radiating patch. The impedance and radiation characteristics of a conventional probe-fed microstrip patch antenna and the proposed microstrip patch antenna are experimentally examined and compared. The effects of the slot length on the antenna operation are also discussed.