Showing papers on "Patch antenna published in 2001"

Wide-band E-shaped patch antennas for wireless communications

Abstract: This paper presents a novel single-patch wide-band microstrip antenna: the E-shaped patch antenna. Two parallel slots are incorporated into the patch of a microstrip antenna to expand it bandwidth. The wide-band mechanism is explored by investigating the behavior of the currents on the patch. The slot length, width, and position are optimized to achieve a wide bandwidth. The validity of the design concept is demonstrated by two examples with 21.2% and 32.3% bandwidths. Finally, a 30.3% E-shaped patch antenna, resonating at wireless communication frequencies of 1.9 and 2.4 GHz, is designed, fabricated and measured. The radiation pattern and directivity are also presented.

Bandwidth enhancement of a microstrip-line-fed printed wide-slot antenna

Abstract: Printed wide-slot antennas fed by a microstrip line with a fork-like tuning stub for bandwidth enhancement are proposed and experimentally investigated. Both the impedance and radiation characteristics of this antenna are studied. Experimental results indicate that a 1:1.5 VSWR bandwidth of 1 GHz is achieved at operating frequencies around 2 GHz, which is nearly ten times that of a conventional microstrip-line-fed printed wide-slot antenna. It also achieved a 2-dB gain bandwidth of at least 0.5 GHz.

A broad-band rectangular patch antenna with a pair of wide slits

Abstract: A new broad-band design of a probe-fed rectangular patch antenna with a pair of wide slits is proposed and experimentally studied. The proposed design is with an air substrate, and experimental results show that, simply by inserting a pair of wide slits at one of the radiating edges of the rectangular patch, good impedance matching over a wide bandwidth can easily be achieved for the proposed antenna. With an air substrate of thickness about 8% of the wavelength of the center operating frequency, the proposed antenna can have an impedance bandwidth of about 24%. For frequencies within the impedance bandwidth, good radiation characteristics are also observed, with a peak antenna gain of about 7.2 dBi.

Novel compact circularly polarized square microstrip antenna

Abstract: A novel compact circular-polarization (CP) operation of the square microstrip antenna with four slits and a pair of truncated corners is proposed and investigated. Experimental results show that the proposed compact CP design can have an antenna-size reduction of about 36% as compared to the conventional corner-truncated square microstrip antenna at a given operating frequency. Also, the required size of the truncated corners for CP operation is much greater than that for the conventional CP design using a simple square microstrip patch, providing a relaxed manufacturing tolerance for the proposed compact CP design. Details of the experimental results are presented and discussed.

Dual-band circularly-polarized square microstrip antenna

Abstract: New designs of obtaining dual-band circular polarization (CP) radiation of a single-feed square microstrip antenna are proposed and experimentally studied. The proposed single-feed dual-band CP designs are achieved by inserting four T-shaped slits at the patch edges or four Y-shaped slits at the patch corners of a square microstrip antenna. From experiments conducted, a patch size reduction as large as 36% for the proposed design, compared to a conventional CP design without the inserted slits, has been obtained. Details of the design considerations of the proposed antennas are described, and experimental results of the obtained dual-band CP performances are presented and discussed.

A shared-aperture dual-band dual-polarized microstrip array

Abstract: This paper describes the design and testing of a prototype dual-band dual-polarized planar array operating at L- and X-bands. The primary objectives were to develop new antenna technology with dual-band and dual-polarization capability in a shared aperture, featuring low mass, high efficiency, and limited beam scanning. The design of a prototype planar microstrip array of 2/spl times/2 L-band elements interleaved with an array of 12/spl times/16 X-band elements that meets these requirements is discussed in detail and measured results are presented. The array is modular in form and can easily be scaled to larger aperture sizes.

Single or dual band parasitic antenna assembly

Abstract: A compact single or multiple band antenna assembly for wireless communications devices. One multi-band embodiment includes a high frequency portion and a low frequency portion, both fed at a common point by a single feed line. Both portions may be formed as a single stamped metal part or metallized plastic part. The overall size is suitable for integration within a wireless device such as a cell phone. The low frequency portion consists of two resonant sections which are stagger tuned to achieve a wide resonant bandwidth, thus allowing greater tolerance for manufacturing variations and temperature than a single resonant section, and is useful for single band antennas as well as multi-band antennas where it may be used to enhance bandwidth for both sections of a dual band antenna as well. The resonant sections for single or multi-band antennas operate in conjunction with a second planar conductor, which may be provided by the ground trace portion of the printed wiring board of a wireless communications device. The antenna assembly provides a moderate front-to-back ratio of 3-12 dB and forward gain of +1 to +5 dBi. The front to back ratio reduces the near field toward the user of a hand held wireless communications device, thus reducing SAR (specific absorption rate) of RF energy by the body during transmit. The antenna pattern beam width and bandwidth are increased for a handset during normal user operation, as compared to a half wave dipole.

Analysis and design of L-probe proximity fed-patch antennas

Abstract: In this paper, the finite-difference time-domain (FDTD) method is employed to analyze L-probe proximity-fed rectangular patch antennas. Numerical results for the input impedance, co- and cross-polarization radiation patterns are presented and compared with the measurements. Good agreement between the computed and measured results is obtained. The effects of geometric parameters on the characteristics of the L-probe patch antenna are extensively studied. For design purposes, the variation of input impedance at resonance with different geometric parameters is plotted on a Smith chart. Mutual coupling between two L-probe patch antennas is also investigated.

Hilbert curve fractal antenna: A small resonant antenna for VHF/UHF applications

Abstract: The usefulness of fractal Hilbert curves in antenna geometry is explored here for the first time. Apart from being simple and self-similar, these curves have the additional property of approximately filling a plane. These properties are exploited in realizing a “small” resonant antenna. This approach has resulted in an antenna size smaller than λ/10 and still resonant, with performance comparable to a dipole whose resonant length is close to λ/2. Numerical predictions of the input impedance of the antenna have been compared with experiments. The effect of additional fractal iterations on the reduction of the resonant frequency has been studied. The radiation characteristics of the antenna at the resonant frequencies provided show that this is very similar to the dipole characteristics. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 29: 215–219, 2001.

A compact microstrip antenna with meandering slots in the ground plane

Abstract: A novel compact microstrip antenna design is demonstrated By embedding meandering slots in the antenna's ground plane, it is observed that the resonant frequency of the microstrip antenna is significantly lowered, which can lead to a large antenna size reduction for a fixed frequency operation In addition, enhanced impedance bandwidth and antenna gain are also observed for the proposed antenna Details of the proposed design and experimental results of the constructed prototypes are presented and discussed © 2001 John Wiley & Sons, Inc Microwave Opt Technol Lett 29: 95–97, 2001

Broad-band single-patch circularly polarized microstrip antenna with dual capacitively coupled feeds

Abstract: New design of a circular microstrip antenna with dual capacitively coupled feeds for broad-band circular polarization radiation is presented. The dual feeds are with a small top-loaded disk and are connected to a Wilkinson power divider with a 90/spl deg/ phase shift between its two output feedlines. The radiating circular patch, printed on a thin substrate, is supported by nonconducting posts on a conducting ground plane and is excited capacitively through the dual feeds. With a distance less than 10% times the center operating wavelength between the circular patch and the ground plane, the present proposed antenna can provide an impedance bandwidth (VSWR /spl les/2) of about 49% and a 3-dB axial-ratio bandwidth of about 35%. The antenna gain bandwidth, defined to be within 1-dB gain variation in the axial-ratio bandwidth, is as large as 28%, with the antenna gain level at about 7.0 dBi.

Group antenna with narrow main lobes in the horizontal plane

Abstract: The invention relates to an antenna device comprising a group antenna (310) with radiating elements (340-347) in M rows and N columns M, where n∫M, which group antenna (310) has a width measurement (b) and a height measurement (h) The group antenna (310) is so arranged in the antenna device that the projection (P) of the group antenna in the sideways direction of the antenna in the horizontal plane (210) exceeds the width measurement (b) of the group antenna, whereby the group antenna is given a narrower main lobe in the horizontal plane (210) A group antenna according to the invention can, in addition, be incorporated in an antenna device (500, 700, 800) which comprises an additional number of similar group antennas (510-532; 710-720; 810-820), arranged on the antenna device along a surface (730, 830) that is circular or a part of a circle, arranged in such a way that the respective projections of the additional group antennas in the sideways direction of the antenna in the horizontal plane also exceed the width measurements of the respective group antennas, whereby the additional group antennas are given narrower main lobes in the horizontal plane

Antenna, and manufacturing method therefor

Abstract: An antenna and a manufacturing method therefor are disclosed, in which the sensitivity characteristic of the dual band antenna utilizing a plurality of frequency bands is improved, and at the same time, the antenna can be miniaturized. A first cylindrical body 110 around which a primary coil 100 is spirally wound is inserted into a second cylindrical body 220 around which a secondary coil is wound. A projected portion of the primary coil 100 is electrically connected to the secondary coil 200, thereby forming a dual band antenna 300.

The dependence of the input impedance on feed position of probe and microstrip line-fed patch antennas

Abstract: The impedance of a rectangular patch antenna fed by an inset microstrip transmission line was measured for various feed positions. The dependence found was then compared to theoretical predictions both for this geometry and for the similar case of an inset coaxial probe feed.

Resonant frequency of circular microstrip antennas with and without air gaps

Abstract: An improved analytical model is presented for calculating the resonant frequency of circular microstrip antennas with and without air gaps. Unlike the previous models, the present one is widely applicable to all patch diameters-from very large to very small compared to the height of the dielectric medium below the patch and also to the substrates covering the entire range of dielectric constants. The computed results for different antenna dimensions and modes of resonance are compared with the experimental values.

Radio communication device with integrated antenna, transmitter, and receiver

Abstract: First to third dielectric layers (201-203) are deposited to form a multilayered dielectric substrate (220). A plurality of conductor patches (204a-204d) are formed on the surface of the first dielectric layer (201). An antenna-feeding microstrip line (205) is formed between the first and second dielectric layers. A ground layer (206) is formed between the second and third dielectric layers (202, 203). Microstrip lines (208a, 208b) for high-frequency circuits are formed on the back of the third dielectric layer (203). The ground layer (206) has a slot (207) though which the antenna-feeding microstrip line (205) and the high-frequency microstrip line (208a) are coupled electromagnetically. Thus, the efficiency and directivity of an antenna are improved.

Adjustable length antenna system for RF transponders

Abstract: The present invention provides an RF tag having an antenna that can be selectively tuned to achieve optimal performance. The RF tag comprises an RF transponder integrated circuit and an antenna connected to the RF transponder integrated circuit. The antenna includes components such as tuning stubs and loading bars that are physically alterable to selectively vary the performance characteristics of the antenna. The tuning stub and loading bar may each further comprising a variably selectable length having elements that may be removed by punching, cutting, etching, laser trimming or other process. The antenna may further comprise a leadframe or a flexible substrate.

Dual polarization stacked microstrip patch antenna array with very low cross-polarization

Abstract: This paper describes the development and performance of a wideband dual linear polarization microstrip antenna array used in the Danish high-resolution airborne multifrequency polarimetric synthetic aperture radar, EMISAR. The antenna was designed for an operating frequency of 1.25 GHz/spl plusmn/50 MHz and was built as an array of 8/spl times/2 probe-fed stacked microstrip patches. The feeding network is constructed in microstrip and is capable of handling 6 kW of peak input-power at an altitude of 45000 ft (unpressurized). The impedance bandwidth (return loss better than -14 dB) of the antenna is 10%, the isolation between the horizontal and the vertical ports of the array is 50 dB and the cross-polarization suppression is 40 dB. A new design principle for simultaneously achieving very low cross-polarization and low side lobes in dual linear polarization antenna arrays has been applied.

Micromachined microstrip patch antenna with controlled mutual coupling and surface waves

Abstract: Silicon micromachining has been used to demonstrate the possibility of building high performance microwave and millimeter-wave antennas. To suppress higher order substrate modes and increase the bandwidth of a patch antenna, silicon substrate has been used and material has been selectively removed under the patch area. In addition, the effect of etched grooves around a patch element has been studied for performance improvement, it has been shown that micromachined substrate structure can effectively suppress unwanted surface wave modes resulting in improved radiation efficiency. Moreover, effective dielectric constant curves for the shielded micromachined substrates are provided for accurate design of patch antennas. We have demonstrated that mutual coupling between the radiating patch elements due to surface waves can be controlled using various micromachined substrate configurations.

Dual band built-in antenna device and mobile wireless terminal equipped therewith

Abstract: A dual band built-in antenna device operable in a first frequency band and a second frequency band is provided. The antenna device comprises a ground plane comprising a ground member, a first inverted-L line antenna element for the first frequency band, and a second inverted-L line antenna element for the second frequency band. The first and second inverted-L line antenna elements are so constructed that the elements are extended to respective directions that are further separated from each other as the antenna elements extend further from a starting position set in proximity to a power feed point within a plane parallel to the ground plane.

Reduced weight artificial dielectric antennas and method for providing the same

Abstract: An artificial anisotropic dielectric material can be used as a microstrip patch antenna substrate. The artificial dielectric can be easily designed for the purpose of weight reduction. Preferably, the artificial dielectric is comprised of a periodic stack of low and high permittivity layers. The layers can be oriented vertically below the patch to support electric fields consistent with desired resonant modes. Substrates may be engineered for both linearly and circularly polarized patch antennas. Antenna weight can be reduced to ⅙th up to {fraction (1/30)}th of the original weight using different types of high permittivity layers. This concept has numerous applications in electrically small and lightweight antenna elements such as PIFA antennas. In accordance with one aspect of the invention, the artificial dielectric is comprised of an interlocking structure of low and high permittivity layers for ease of assembly and for overall stability. In accordance with another aspect, the high permittivity layers can be comprised of FSS cards, and can include metallized tabs for further simplification of assembly.

Design considerations for integrated mobile phone antennas

Abstract: Based on the investigation of the board effect on the bandwidth of integrated antennas for mobile phones a concept for a tripleband antenna suitable for GSM/DCS/PCS is developed. The antenna concept comprises a parasitic element to enlarge the bandwidth. The performance of the antenna is analyzed by means of numerical simulations based on the FDTD method.

Non-contact communication system, and auxiliary device and method for non-contact communication

Abstract: PROBLEM TO BE SOLVED: To extend a communication range. SOLUTION: A non-contact communication system comprises an R/W device 11 provided with an R/W antenna 22 resonating with a communication carrier frequency, a TAG device 12 provided with a TAG antenna 23 resonating with the communication carrier frequency, and an antenna sheet 61 operating as an antenna resonating with the communication carrier frequency. The R/W antenna 22 is electromagnetically coupled with a first coupling part 112 of the antenna sheet 61, and a second coupling part 113 is electromagnetically coupled with the TAG antenna 23 by a circulating magnetic field around a lead of the second coupling part 113 or the TAG antenna 23 produced by a line current flowing through the lead. The R/W device 11 and the TAG device 12 carry out non-contact communication with each other via the electromagnetically coupled R/W antenna 22, the antenna sheet 61, and the TAG antenna 23. COPYRIGHT: (C)2003,JPO

An antenna apparatus and a portable wireless communication apparatus

Abstract: A microstrip antenna (MSA) above a ground plane, having a size corresponding to an operation frequency, at a junction point thereof, electrically connected to one end of a monopole antenna having a size corresponding to the operation frequency to operate as a complex antenna. A distance between the feed point of MSA and the junction point determines the input impedance for matching. A microstrip line or an (planer) inverted-F antenna may provide the MSA. The monopole element may be a monopole antenna or helical antenna. A portable wireless communication apparatus includes the antenna apparatus having a housing. The monopole antenna is connected to the MSA when the monopole antenna is extended from the housing. A switch may be provided between the monopole antenna and the MSA for diversity operation. The antenna apparatus may be formed on a Printed circuit board and folded.

Small and high-directivity bow-tie patch antenna based on the Sierpinski fractal

Abstract: The unique geometrical properties of fractals have been proven to be useful to design advanced antennas. Enhanced performance in terms of size, gain, or multifrequency behavior is observed in fractal-shaped antennas. Here, a small and high-directivity antenna based on the Sierpinski fractal is presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 239–241, 2001.

Antenna for RFID

Abstract: An antenna for RFID which can be mounted directly on the surface of a management object without using a spacer whatever material the surface of the object might be made of. This RFID antenna (14) is mounted on an article (11) electrically connected with an IC chip or capacitor, and comprises a conductive member (14a) formed into a flat plate and mounted on the article at its back and a coil body (14b) fixed directly or with a predetermined spacing on a conductive member, spirally wound and having such a number of turns or a diameter that it has a predetermined characteristic value in the wound state.

Method and system for producing dual polarization states with controlled RF beamwidths

Abstract: An antenna system can generate RF radiation fields having dual simultaneous polarization states and having substantially rotationally symmetric radiation patterns The antenna system generates RF radiation patterns where the beamwidths of respective RF fields for respective radiating elements are substantially equal and are relatively large despite the compact, physical size of the antenna system The antenna system can include one or more patch radiators and a non-resonant patch separated from each other by an air dielectric and by relatively small spacer elements The patch radiators and non-resonant patch can have predefined shapes for increasing polarization discrimination The lower patch radiators can be mounted to a printed circuit board that can include an RF feed network and a ground plane which defines a plurality of symmetrically, shaped slots The slots within the ground plane of the printed circuit board can be excited by stubs that are part of the feed network of the printed circuit board The slots, in turn, can establish a transverse magnetic mode of RF radiation in a cavity which is disposed adjacent to the ground plane of the printed circuit board and a ground plane of the antenna system The feed network of the printed circuit board can be aligned with portions of the cavity such that the portions of the cavity function as a heat sink for absorbing or receiving thermal energy produced by the feed network

Tunable patch antenna

Abstract: A patch antenna is composed of a segmented patch and MEMS switches which are built on a substrate. The patch segments of the segmented patch can be electrically connected to each other by the MEMS switches to form a contiguous patch and optional tuning strips and to connect or block RF between the contiguous patch and the optional tuning strips. When RF is connected between the tuning strips and the contiguous patch, the tuning strips increase the effective length of the contiguous patch and lower the antenna's resonant frequency, thereby allowing the antenna to be frequency tuned electrically over a relatively broadband of frequencies. When the tuning strips are connected to the patch in other than a symmetrical pattern, the antenna pattern of the antenna can be changed. In another aspect of the invention, the optional tuning strips are continuous structures that are formed by connecting patch segments using switches. A planar inverted F antenna (PIFA) is also provided with one or more tuning strips spaced from the lid of the PIFA and with switches to connect or block RF between the lid of the PIFA and the tuning strips.

High‐directivity patch antenna with both photonic bandgap substrate and photonic bandgap cover

Abstract: A new patch antenna system, which has both a photonic bandgap (PBG) substrate and a PBG cover, is proposed in the present paper. The impedance, radiation pattern, and directivity of such an antenna are studied by the finite-different time-domain method. The results show that the directivity of the PBG antenna is significantly improved. The dependence of the directivity on the frequency and other parameters is also studied. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 30: 41–44, 2001.