Showing papers on "Patch antenna published in 1996"

A circularly polarized small-size microstrip antenna with a cross slot

Abstract: An antenna with a low profile, small size, and a light weight is required in mobile satellite communications. A new, circularly polarized small-size microstrip antenna using a proximity coupled feed method is proposed. A simple configuration based on a cross slot with unequal slot lengths on a circular patch is adopted to realize a small-size element antenna. The proposed antenna has no 90/spl deg/ hybrid coupler for circular polarization. The measured results verify the circular polarization, and the antenna radius was reduced by about 36% by using the slot lengths which are nearly equal to the diameter of the circular patch antenna. Good impedance and axial ratio characteristics have been obtained.

Flat lens antenna concept using aperture coupled microstrip patches

Abstract: A planar lens antenna based on aperture coupled microstrip patch elements with stripline delay lines is described. Features of this design are discussed, and results for transmission coefficient magnitude against frequency are presented. The background for the development of this lens configuration is discussed in terms of a natural progression from frequency selective surfaces, and the inadequacies of simpler geometries are explained.

A planar dual-frequency array antenna

Abstract: A dual-frequency array antenna having an essentially planar structure with electronic beam steering capability in both a low and high frequency band independently of each other, constructed, in a layered formation, from a top planar array antenna unit operating in the low frequency band and a bottom planar array antenna unit operating in the high frequency band. The top planar array antenna is transparent to frequencies in the high frequency band.

Stacked microstrip antenna with wide bandwidth and high gain

Abstract: A stacked microstrip antenna with two parasitic elements, one of which increases the impedance bandwidth and the other which enhances the gain, has been investigated experimentally. The effects of each parasitic element have been clarified as well as the characteristics of the stacked three-element antenna and the design procedure for the stacked microstrip antenna have been described.

Compact microstrip patch antenna

Abstract: This article describes the design and development of a relatively compact microstrip patch antenna. At resonance, the length of the antenna is approximately one-eighth of the effective wavelength. The current distribution on the patch surface has been analyzed with the use of the method of moments. © 1996 John Wiley & Sons, Inc.

Surface Mounting Antenna and Communication Apparatus Using the Same Antenna

Abstract: A surface mounting antenna in which a wider frequency bandwidth can be achieved and a dual-frequency signal can be obtained without hampering the gain and needing to enlarge the configuration of the antenna. Also disclosed is a communication apparatus using this type of antenna. Two radiation electrodes for producing different resonant frequencies and a feeding electrode are formed on the obverse surface of a substrate formed of a dielectric material or a magnetic material. A ground electrodes is primarily disposed on the reverse surface of the substrate. The radiation electrodes form open ends and are connected at the other ends to the ground electrode. The open ends of the radiation electrodes and the feeding electrode are electromagnetically coupled to each other through capacitances generated in gaps formed between the feeding electrode and the open ends.

Ring shaped antenna

Abstract: An antenna for broadcasting omnidirectionally is disclosed. The antenna includes a cylindrical housing which has a lip which includes slots adapted to receive a patch antenna strip and a conductive ring. A GPS receiver and electronics package may be placed in the center of the housing. The patch antenna strip which includes a number of patch antennas broadcasts and receives radio signals. The conductive ring absorbs energy broadcast from the patch antennas and rebroadcasts the signal omnidirectionally. The resulting signal has a high gain and a wide bandwidth. A third embodiment in which the conductive ring is incorporated into a housing cover is also disclosed. The antenna is easily and inexpensively assembled and is more durable and reliable than prior art antennas.

Antenna array in an RFID system

Abstract: In accordance with the present invention, a general antenna system is disclosed suitable for applications in which an RFID Tag passes by an Interrogator. We then disclose a specific antenna design that uses a single planar antenna for transmit and a multi-element planar antenna array for receive. The multi-element planar antenna array is spaced such that each of the planar elements is four inches apart, center-to-center, thus defining a narrow 30° receive beamwidth in the horizontal plane. The vertical receive bandwidth is much greater than 30°, facilitating the Interrogator receiving signals at a variety of elevations. Furthermore, a multi-way microstrip combiner is used to sum the signals received from each of the planar antennas. To block interference from the transmit antenna and to improve receive sensitivity, this multi-way microstrip combiner is shielded using, in one embodiment, copper tape along its edges. In a specific embodiment, a four element receive antenna design is disclosed.

Analysis and design of feeding structures for microstrip leaky wave antenna

Abstract: Three arrangements of the feeding structure for the excitation of a microstrip leaky wave antenna are proposed and investigated in this paper. A full-wave spectral domain integral equation method combined with the fundamental mode sampling technique is applied to determine the reflection coefficient of the excitation source. Tabulation technique is used to reduce the computational effort. Dependence on structural parameters such as line width, line spacing and overlap length is fully analyzed to obtain the design criteria for a microstrip leaky wave antenna. Additionally, an experimental setup is used to check the validity of our numerical results and verify the radiation nature of the microstrip line first higher-order mode.

A small microstrip patch antenna with a convenient tuning option

Abstract: The paper addresses two aspects of resonant microstrip patch antennas, namely, miniaturization and resonant frequency tuning. First, a patch geometry which allows a controllable size reduction over a limited range is presented. The basic shape is circular with slits cut into it. Modification of the slit geometry leads to both linear as well as circular polarized (CP) operation. Second, the use of another patch of a specific shape as a superstrate layer in a stacked configuration allows tuning over a relatively large frequency range as compared to the patch bandwidth. Tuning is accomplished by a simple rotation of the superstrate layer. The use of another superstrate layer allows tunable CP operation. Details on the antenna characteristics have been worked out for two examples, and computations have been compared with measurements where possible. Some design guidelines have also been included.

New compact microstrip antenna

Abstract: A new microstrip antenna geometry with considerable reduction in size, with similar radiation characteristics to those of an equivalent rectangular patch antenna is proposed. A relationship has been suggested for finding out the resonant frequency of the new geometry, and its validity has been established by the experimental results. Without increasing the aperture area, this geometry also offers a facility for considerably reducing the resonant frequency compared to conventional patches.

A simple feed model that reduces time steps needed for FDTD antenna and microstrip calculations

Abstract: The finite-difference time-domain (FDTD) method is being widely applied to antenna and microstrip calculations. One aspect of this application is accurately and efficiently modeling antenna and microstrip feeds within the constraints of the FDTD approximations. Several relatively straightforward approaches have been suggested, including gap and frill feeds. More complicated approaches, which involve including the coaxial feed cable in the FDTD calculation space, have also been suggested. A related aspect is the desirability of reducing the number of time steps required for the FDTD calculations to converge, especially for transient excitation. We illustrate that for many geometries a simple gap model with an internal source resistance provides accurate results while greatly reducing the number of time steps required for convergence.

Wideband aperture coupled stacked patch antenna using thick substrates

Abstract: An aperture coupled stacked patch microstrip antenna is presented which is capable of operating over a bandwidth in excess of 50%. Measured and predicted impedance behaviour and gain over the band are given. Other important factors such as surface wave efficiency and back radiation levels are presented.

Switch-tuned meandered-slot antenna

Abstract: An electrically-short meandered-slot antenna having a plurality of switch-selected resonant frequencies is described. Meander slot sections are substantially parallel, closely coupled, electrically significant, and substantially equal in length to the overall monopole length of the antenna. Switching among resonant frequencies is accomplished with shunt switches across the antenna slot, the switches preferably being powered inductively and selectively at individual frequencies outside the operating band of the antenna.

Contrawound toroidal helical antenna

Abstract: An electrically small antenna is disclosed that is constructed from a generalized contrawound toroidal helix (1, 2) made from a single continuous conductor divided into two length portions each of which are substantially the same length and which have a generalized helical pattern. The helical pitch senses the two length portions are opposite to one another. The two length portions are insulated from one another and overlap one another on the surface of a generalized toroid. A signal is fed to the antenna at a port defined by the node locations (N1, N2) where the respective length portions join one another, or at a diametrically opposite point. A compact, broadband embodiment of the antenna is disclosed, as are other applications including a coaxial cavity resonator using the antenna as a feed element.

Antenna system for radio signals in at least two spaced-apart frequency bands

Abstract: In an antenna system for radio signals in at least two spaced-apart frequency bands above 200 MHz, a quadrifilar helical antenna having an elongate dielectric core with a relative dielectric constant greater than 5 has a conductive sleeve surrounding a proximal part of the core and a longitudinal feeder structure extending through the core to a connection with the helical antenna elements at a distal end of the core. The antenna is operated in an upper frequency band in which it exhibits a first mode of resonance characterized by current maxima at the connections of the helical elements to the feeder structure and at their junctions with the rim of the sleeve, and in a lower frequency band in which the antenna exhibits a second mode of resonance characterized by current minima in the region of the junctions of the helical elements and the sleeve rim. To permit dual mode operation, the antenna system includes an impedance-matching diplexer having filters coupled between a common port for the antenna and further ports for connection to radio signal processing equipment such as a GPS receiver and a mobile telephone operating in the two frequency bands. In the preferred embodiment, the filters and impedance matching elements are formed as microstrip elements on a single substrate.

The resonant frequency of rectangular microstrip antenna elements with various substrate thicknesses

Abstract: Formulas based on transmission-line, cavity, and magnetic-wall models to determine the resonant frequencies of a rectangular microstrip antenna element have been studied and their validity assessed. Their variations were experimentally verified by analyzing a set of newly designed antenna elements with substrates satisfying the criteria h ≤ 0.0815λ0 for 2.22 ≤ ϵr ≤ 10.2, where λ0 is the free-space wavelength, h the thickness, and ϵr the relative permittivity of the dielectric substrate. © 1996 John Wiley & Sons, Inc.

Oscillator-type active-integrated antenna: the leaky-mode approach

Abstract: This paper describes basic research carried out to design a microwave source module employing the concept of an active-integrated leaky-mode antenna. The novel active-antenna source module utilizes a microstrip as the radiating element while adopting uniplanar technology for the active circuit design. The microstrip is operated in the first higher order odd mode, which is a leaky mode, and excited by a proximity-coupled center-fed slotline on the same surface of the uniplanar microwave-integrated circuit. The measured performance of an X-band transmission-type injection-locked active-integrated antenna source module demonstrated that such a design approach was suitable for linear array integration for quasi-optical power combining. The harmonic-balance (HB) analysis of the proposed active-integrated antenna agrees with the measurements in both free-running frequency and power level. The measured radiation patterns of the active-integrated antenna also agree well with the theoretical predictions.

Flat-top antenna apparatus including at least one mobile radio antenna and a GPS antenna

Abstract: The flat-topped antenna apparatus includes a GPS antenna, a mobile radio antenna, a common housing for the antennas mounted over a ground plane and coaxial cables (12,13,13a) acting as electrical supply lines for the antennas. The mobile radio antenna includes a metal sheet (6,6',6a) plane parallel to the ground plane and spaced at a distance (A,A') of 0.04 of an average operating wavelength of a mobile radio frequency band from the ground plane. The metal sheet is electrically connected at an input terminal (11) with an inner conductor (10) of one coaxial cable (13,13a) and also with the ground plane via a short circuit element (7,7a). The GPS antenna is above and rests on the mobile radio antenna and includes a dielectric plate (1,1a) provided with a metal layer (3) connected at an input terminal (4) with an inner conductor (10) of another (12) of the coaxial cables. The end points (14,15) of the outer conductors of the coaxial cables located near the respective input terminals (4,11) of both antennas are electrically connected to ground. At least one outer conductor is electrically connected to ground again at a connection point (16) which is located at a distance (d 1/4 ) of one quarter of the average operating wavelength from the grounded end point of the at least one outer conductor.

A single-layer dual-frequency rectangular microstrip patch antenna using a single probe feed

Abstract: A simple design of a dual-frequency microstrip antenna using a single rectangular patch and a single probe feed is described. Experimental results of the antenna resonating at frequencies of about 1.42 and 1.54 GHz are presented. Measurements are verified by the theoretical results obtained from full-wave solutions. © 1996 John Wiley & Sons, Inc.

Wideband sub-wavelength antenna

Abstract: A wideband antenna has a planar conductive tab, a planar ground plane and transmission line. The conductive tab is sub-wavelength in all dimensions and has a top edge that is wider than its bottom end. The width of the conductive tab tapers from the top edge to the bottom end. The ground plane is parallel with and located below the conductive tab. The wideband antenna of the present invention, called a tab monopole, is planar in form enabling it to be readily manufactured using standard printed circuit board methods and facilitating its integration with packages and radio frequency circuitry used to feed the antenna. Operational bandwidths in excess of 40% were realized by this wideband, sub-wavelength antenna.

Design of a dual frequency reflectarray using microstrip stacked patches of variable size

Abstract: A new stacked microstrip reflectarray, based on patches of variable size, is proposed for dual frequency operation A progressive phase distribution is achieved for the reflected wave at both frequencies by adjusting the resonant length of the patches in each elementary cell of the reflectarray

Coaxial resonant slot antenna, a method of manufacturing thereof, and a radio terminal

Abstract: A coaxial resonant slot antenna having a novel structure is provided to further reduce the dimensions of radio terminals incorporating such an antenna. Also provided are a novel method of fabricating such a coaxial resonant slot antenna and a radio terminal having a novel structure using such a coaxial resonant slot antenna. An entire strip conductor is arranged inside a flat conductive cubic such that the strip conductor is insulated from the conductive cubic. A connection point between the strip conductor and a radio frequency transmission line is provided at a position about 1/4 of wavelength away from one end of the strip conductor. A slot is shaped into a narrow rectangle, a generally upside-down "U", or a generally upside-down "U" having another slot on each end. It is desired that the center slot crosses the strip conductor along the length thereof and in the height direction thereof, the distance between the ends being equivalent to about 1/2 of wavelength used. The radio terminal has a plurality of antennas associated with the present invention arranged on a plurality of surfaces and provides a connection mechanism for varying the number of antennas to be used in the talk mode and the standby mode.

An investigation of a novel broadband dielectric resonator antenna

Abstract: Recently, dielectric resonator antennas (DRA) have been proposed as an alternative to the popular microstrip patch. Since then, research has continued, extending their performance capabilities and confirming their potential as low profile and efficient antenna elements for array applications. Also a single-point fed dielectric resonator antenna has been reported, capable of radiating a circularly polarized signal with a much wider axial ratio bandwidth than a similar single-point fed microstrip patch. Further capability enhancements of a dielectric resonator antenna have recently been demonstrated by fabricating the antenna from ferrite material. With a properly biased static magnetic field, it has been shown to possess frequency tuning and polarization diversity properties. The purpose of this paper is to present a novel development of a DRA which possesses a much wider operational bandwidth than previously reported. This improvement can be accomplished with a simple slot feed and without an elaborate matching circuit or a complicated stacking procedure which is generally required by the microstrip patch.

Performance of a cross-aperture coupled single feed circularly polarised patch antenna

Abstract: A novel method for radiating circular polarisation (CP) with a patch antenna without an external polariser has been investigated. It has the advantage of improving the axial ratio bandwidth for single feed CP antennas by using a thick air substrate and inverted patch configuration.

Microstrip antenna device

Abstract: In a microstrip antenna device which has a radiating patch 11 and a ground plate disposed opposite and in parallel to each other, a metal plate 21 is provided on the ground plate in the vicinity of at least one of opposite marginal edges of the radiating patch 11 in the direction of resonance to form an additional capacitance between an open end of the radiating patch in the direction of resonance and the ground plate, thereby permitting reduction of the antenna length.

Experimental study of the rectangular patch with a U-shaped slot

Abstract: Huynh and Lee (see Electronics Letters, vol.31, no.16, p.1313, 1995) presented measurements which showed that a coaxially fed rectangular patch with a U-shaped slot can attain 10-40% impedance bandwidth, with good pattern characteristics. In contrast to the method of bandwidth enhancement using parasitic patches which either increase the thickness or the lateral size of the antenna. The U-slot patch is a single-layer single-patch wideband structure which preserves the thin profile and small size advantages of the microstrip antenna. We present extensive experimental results on the U-slot patch, including cross polarization measurements and the effects of patch size, slot size and feed position on the performance. The results of a two-element array of U-slot patches are also presented.

Circularly polarised higher-order rectangular dielectric-resonator antenna

Abstract: A circularly polarised, rectangular, low-profile, dielectric-resonator antenna is presented which is fed by a 50/spl Omega/ microstrip line through a single aperture. The measured 3dB axial-ratio bandwidth in the boresight direction is 14.35-14.80 GHz (3%). At 14.75 GHz, the input |s/sub 11/| is -28 dB; the measured pattern in one elevation plane decreases with increasing /spl theta/ but the axial ratio is close to 3 dB over 110/sup c/; in the orthogonal elevation plane, the axial ratio increases more rapidly with /spl theta/.

Wideband, stacked double C-patch antenna having gap-coupled parasitic elements

Abstract: A stacked, shorted double C-patch antenna (100) has gap-coupled parasitic elements (102a, 106a, 102b, 106b) and one directly fed antenna element (104a). A second fed element (104b) is conductively fed from the directly fed element. The antenna has a truncated ground plane (108) and a bandwidth that is equal to or greater than approximately 70 MHz at a frequency of approximately 850 MHz. The directly fed antenna element is conductively coupled to a transmitter and to a receiver of a communications device, such as a cellular telephone.