Showing papers on "Slot antenna published in 1998"

Design and performance of small printed antennas

Abstract: Electrically small microstrip patches incorporating shorting posts are thoroughly investigated. These antennas are suitable for mobile communications handsets where limited antenna size is a premium. Techniques to enhance the bandwidth of these antennas are presented and performance trends are established. From these trends, valuable insight to the optimum design, namely broad bandwidth, small size, and ease of manufacturing, is given.

Micromachined patch antennas

Abstract: This paper presents the use of selective lateral etching based on micromachining techniques to enhance the performance of rectangular microstrip patch antennas printed on high-index wafers such as silicon, GaAs, and InP. Micromachined patch antennas on Si substrates have shown superior performance over conventional designs where the bandwidth and the efficiency have increased by as much as 64% and 28%, respectively. In this work, the silicon material is removed laterally underneath the patch antenna to produce a cavity that consists of a mixture of air and substrate with equal or unequal thicknesses. Characterization of the micromachined patch antenna is presented herein and includes a discussion on the bandwidth improvements, radiation patterns, and efficiency of the patch. In addition, antenna placement on the reduced index cavity with respect to the high-index substrate is described to achieve efficiency improvements over conventional patch antennas.

Tapered slot antenna

Abstract: A tapered slot antenna includes a dielectric sheet, a conductor layer laminated on said dielectric sheet, in which conductor layer a tapered slot pattern is formed as a result of a slot width of a slotline being widened gradually, and corrugated structures provided at two sides of said conductor layer, parallel to a direction in which an electromagnetic wave is radiated from said antenna. The shape of said antenna is axially asymmetrical.

Frequency-scanned end-fire phased-aray antenna

Abstract: A frequency-scanned end-fire phased-array antenna includes a board, a sinuous transmission line formed on the board, a plurality of end-fire antennas, and a plurality of couplers corresponding to the end-fire antennas, such that the transmission line is selectively coupled to the plurality of end-fire antennas via the plurality of couplers, for selectively coupling energy within the transmission line to the end-fire antennas. By varying the input frequency to the antenna over a narrow range, the direction of a main radiation beam emitted by the antenna can be scanned ±90 degrees from broadside. A single antenna board produces a frequency-scanned fan beam. Stacked antenna boards can produce a frequency-scanned pencil beam, or several independent frequency-scanned fan beams at different frequencies. The present antenna can operate in the microwave, millimeter-wave, terahertz, infrared, or optical frequency range. Because this frequency-scanned phased-array can be mass produced by planar fabrication techniques, it can be much smaller and less expensive than conventional "hollow pipe" waveguide frequency-scanned phased-array antennas.

Double U-slot rectangular patch antenna

Abstract: A rectangular microstrip antenna with two U-shaped slots on the patch is described. Using a foam layer of thickness /spl sim/8% wavelength as the supporting substate, an impedance bandwidth of 44% is achieved. The radiation patterns are stable across the passband.

On-chip antenna, and systems utilizing same

Abstract: One or more antennas are formed on an integrated circuit (IC) chip and connected to other circuitry on the IC chip. Antenna configurations include loop, multi-turn loop, square spiral, long wire, or dipole. The antenna may be formed to have two or more segments which can selectively be connected to one another to alter an effective length of the antenna. Two antennas may be formed in two different metallization layers separated by an insulating layer. Additionally, an antenna may be incorporated in a heat sink structure that is joined to the IC chip. IC chips having antennas are suitably included in a system or subsystem having electrical functionality, such as general purpose computers, telecommunications devices, and the like.

Dual band antenna for vehicles

Abstract: A dual band slot antenna for cellular telephone and GPS frequency bands. The antenna is a slot antenna formed in a conductive layer laminated to a layer of a windshield or other transparency. The slot is formed along two adjoining arcs of a circle extending oppositely from a feedpoint, with a portion of the conductive layer interposed between the ends of the slots. The two slot legs have different lengths so the slot is tuned to exhibit at least two resonant peaks, such as one at the cellular telephone frequency band and the other at the GPS frequency band. The slot is fed by strip line transmission lines or capacitive coupling, using additional conductive film patches spaced by one or more layers of the window, with the window layer forming a dielectric.

Circularly polarised microstrip antenna with a tuning stub

Abstract: A simple circular polarisation (CP) design of microstrip antennas using a tuning stub is proposed and studied. It is also demonstrated that, by applying this CP design method to a circular microstrip patch with a cross slot having equal slot lengths, a compact circularly-polarised microstrip antenna can easily be implemented, with much more relaxed manufacturing tolerances as compared to the case of using a cross slot of unequal slot lengths. Details of the antenna designs are described, and experimental results are presented and discussed.

Performance of a meandered line as an electrically small transmitting antenna

Abstract: For antennas to radiate at maximum efficiency, their dimensions must be on the same order as the radiated wavelength At frequencies below 30 MHz, antennas with efficient radiation are often too large for mobile and portable applications Smaller antennas can be made to radiate efficiently by use of matching networks For installation convenience and ease of adjustment, these networks are usually placed between the transmitter and the antenna input; but it has been found that for best radiation efficiency, matching network elements should be placed at points on the antenna structure Unfortunately, such matching networks must be tuned for each transmitting frequency and, when mounted on the antenna, they cannot easily be tuned A meander element antenna was found to present some electrical and mechanical properties allowing convenient placement of tuning elements when configured as an electrically small transmitting antenna Some simplified design guidelines were derived from experimental data

Characteristics of a MM-wave tapered slot antenna with corrugated edges

Abstract: We discuss how the radiation pattern of a reduced ground plane tapered slot antenna (TSA) is improved by varying the dimensions of a corrugated structure present at the edge of the TSA substrate. Experimental results are given that indicate that E-plane radiation patterns can be adjusted by varying the corrugation structure geometry. We also present calculated analyses of the corrugation structure using the finite-difference time-domain (FDTD) method.

Microstrip antennas for SAR applications

Abstract: This paper discusses various methods of implementing a shared-aperture dual-frequency dual-polarized array antenna for spaced-based synthetic aperture radar (SAR) applications. After evaluating the use of several potential array architecture concepts and radiating elements, a design using interlaced C-band microstrip patches and X-band printed slot elements was chosen as the best choice for the present system requirements. Layout considerations for the two arrays and their associated feed networks are addressed in terms of a practical design. A dual-frequency (C- and X-band), dual-linear polarized SAR array antenna prototype was designed, fabricated, and tested. The principal goal of this effort was to demonstrate the viability of the dual-band dual-polarized array concept, and this has been accomplished. Test results are shown with good correlation between measured and predicted results, validating the design approach used. This work demonstrates that a dual-frequency dual-polarization SAR antenna within a single aperture is a feasible approach to meeting user requirements in future SAR spacecraft.

Single-feed dual-band circularly polarised microstrip antenna

Abstract: A novel technique for obtaining dual-band circular polarisation (CP) radiation of a single-feed circular microstrip antenna is proposed and demonstrated. By embedding two pairs of arc-shaped slots of proper lengths close to the boundary of a circular patch, and protruding one of the arc-shaped slots with a narrow slot, the circular microstrip antenna can perform dual-band CP radiation using a single probe feed. Details of the antenna design and experimental results are presented.

Optically transparent microstrip patch and slot antennas

Abstract: An antenna (10, 110, 210) comprising a ground layer (30, 130, 230), a feed layer (50, 150, 250), an antenna layer (40, 140, 240) and a transparent dielectric substrate (20, 120, 220) interposed between two of the layers (30 and 40, 140 and 150, 230 and 250). An electromagnetic field is produced between the ground layer (30, 130, 230) and the antenna layer (40, 140, 240) when the feed and ground layers (50 and 30, 150 and 130, 250 and 230) are exposed to a microwave frequency above 3,000 megahertz for transmission and when the antenna and ground layers (40 and 30, 140 and 130, 240 and 230) are exposed to a microwave frequency above 3,000 megahertz, for reception. The ground layer (30, 130, 230), feed layer (50, 150, 250) and antenna layer (40, 140, 240) are made of an optically transparent and electrically conductive material. About 30% of the visible light impinging on the antenna (10, 110, 210) passes through the antenna.

Antenna for mobile communications device

Abstract: A new category of mobile communications antenna is implemented in a single layer of conducting material. Wire-slot sections, including wire-tabs defining slots in the material, partially extend around the perimeter of at least one patch-tab section of the antenna. The perimeter of the at least one patch-tab section forms one edge of each slot, and the wire-tab of a wire-slot section forms a second edge of the slot. The wire-tabs of the wire-slot sections are separated from the patch-tab section by the slots and merge into the patch-tab section at a desired point. The length of each of the wire-slot sections may vary. A portion of each of a pair of the wire-tabs of the wire-slot sections functions as an input feed. The patch-tab section may be implemented as a single tab or as a plurality of tabs separated from one another by a slot. By varying the relative geometries of the patch-tab, wire-slots and tabs of the wire-slots, the electrical properties of the antenna, including the input impedance, can be adjusted.

Single-feed dual-frequency rectangular microstrip antenna with square slot

Abstract: By cutting a square slot at the centre of a rectangular microstrip patch, both compactness and dual-frequency operation can be achieved. Several designs have been implemented. From the experimental results obtained, the required antenna size using the proposed design method can be reduced by /spl sim/17% compared to that of the conventional design method using a simple patch without the slot. Typical experimental results are presented and discussed.

Tunable slot antenna

Abstract: In order to offer a tunable slot antenna capable of varying an impedance matching center frequency thereof, there is provided a coaxial resonant slot antenna for supplying RF power to a strip conductor placed in a flat conductive cubic with a slot formed in its upper surface and electrically insulated from the flat conductive cubic, wherein a variable capacitor is electrically connected between one point lying in the neighborhood thereof including an end far from a RF power connection point on the strip conductor and a side wall of the flat conductive cubic, and a d.c. voltage to be applied across the variable capacitor is supplied to the connection point.

L-probe proximity fed U-slot patch antenna

Abstract: The design and measured results of a rectangular U-slot patch antenna proximity fed by an L-shaped probe are described. Using a foam layer of thickness /spl sim/7% wavelength as a supporting substrate. An impedance bandwidth of 42.7% and a gain of 6.7 dBi has been achieved. The radiation patterns obtained are stable across the passband.

CPW-fed slot antenna with wide radiating apertures

Abstract: A new wide slot antenna with capacitively coupled CPW-feed and metallic strips in the apertures is presented. The numerical analysis is based on the Galerkin moment method in the spectral domain approach. A simplified formula to calculate the input impedance is proposed. Theoretical and experimental results demonstrate the significant performance improvement of this modified structure. The influence of various design parameters is investigated. A 50% impedance bandwidth (SWR<2.0) and cross-polarisation levels below -20 dB are demonstrated.

Integrated modified rectangular loop slot antenna on substrate lenses for millimeter- and submillimeter-wave frequencies mixer applications

Abstract: A coplanar waveguide (CPW)-fed rectangular-loop slot antenna with built-in tuning and DC-return capabilities on extended hemispherical lenses is examined. The proposed configuration is scalable up to the submillimeter-wave frequencies. For designing and analyzing the impedance characteristics of the proposed antenna, a multilayer method of moments (MoM) solver has been developed based on the mixed potential integral equation (MPIE) formulation. The corresponding patterns through the lens are obtained using geometrical optics and the surface equivalence principle. Three models have been simulated and one of them has been built and tested at 65 GHz. The integrated antenna exhibits tuning capability, rotationally symmetric patterns, high directivity, good Gaussian coupling efficiency, and a reasonable bandwidth. In addition, computed results agree well with measurements and are used to characterize the input impedance and pattern behavior of the antenna.

A versatile leaky-wave antenna based on stub-loaded rectangular waveguide .I. Theory

Abstract: A new leaky-wave antenna is presented that possesses many desirable features and is suitable for application to both the millimeter-wave and microwave ranges. These desirable features, some of which are unusual, include a simple configuration, a wide flexibility in the range of available beamwidths, the ability to control the beamwidth and the direction of the beam essentially independently, and negligible cross polarization at all scan angles. The antenna structure consists of a parallel-plate stub guide of small height, less than a half wavelength, located off center on the top of rectangular waveguide. The beamwidth is easily controlled from very wide to very narrow by adjusting the stub width or location. The article presents the principle of operation and the theory, employing a new transverse equivalent network that is accurate, but also simple, so that it permits rapid and inexpensive numerical calculations.

A dual-polarized slot antenna for millimeter waves

Abstract: We describe a new dual-polarized slot antenna to be used with quad-optical devices such as superconductor-insulator-superconductor (SIS) mixers at millimeter and submillimeter wavelengths. The radiation and impedance characteristics of the antenna were obtained from a moment-method calculation. The antenna has an excellent radiation pattern, a low impedance, wide bandwidth, and low cross polarization.

Broadband power amplifier integrated with slot antenna and novel harmonic tuning structure

Abstract: A high efficiency class-AB GaAs FET power amplifier integrated with a slot antenna has been designed and fabricated. Broadband second harmonic tuning was achieved using a microstrip line with a periodically etched ground plane. Power-added efficiency greater than 50% was achieved in the 3.7-4.0 GHz bandwidth.

CPW-fed bow-tie slot antenna

Abstract: A CPW-fed bow-tie slot antenna is presented. Experimental results show that the widest bandwidth can be adjusted by the slot width when the extended angle is zero, while the far field is in the broadside direction and the cross polarization is kept at a low level. The bow-tie slot antenna can obtain at least 36% bandwidth (VSWR<2) with a 20° extended angle. A smaller slot width needs a larger extended angle to reach the widest bandwidth; meanwhile, the far field has a wider 3 dB beamwidth in the H-plane than that using a larger slot width. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 19: 358–360, 1998.

Compact dual-frequency microstrip antenna with a pair of bent slots

Abstract: A novel, compact, dual-frequency design for cutting a pair of bent slots in the centre of a rectangular patch is demonstrated. For fixed dual-frequency operation, the proposed design provides an antenna-size reduction as high as 32%, compared to that of using a simple patch without the slots. Experimental results of the proposed design, with various sizes of the bent slots, are presented and analysed.

Network modeling of an inclined and off-center microstrip-fed slot antenna

Abstract: This paper describes a general method for analyzing a microstrip-fed slot antenna with a view to developing an improved network model featuring an inclined and off-center slot. The network model consists of an ideal transformer, a radiation conductance, and extended slotlines terminated by short circuit. The transformer turn ratio can be calculated by combining the reciprocity theorem with the spectral-domain immittance approach. The radiation conductance is determined by the radiated power from the slot in the forms of space and surface waves in the spectral domain. Then network models corresponding to several variations of the antenna are described and the series impedances are computed. The computed results using the network model are compared with the rigorous solution and measurements and good agreements are obtained.

Door approach communication apparatus and door lock control apparatus

Abstract: A door approach transmission apparatus comprises an outside door handle 20 having a conductor with a slit 23 disposed in the door handle surface. A slot antenna 21, 23, 24, 25 is disposed at the slit 23 , and includes feeding points 24, 25 installed on the conductor. The apparatus also includes a transmitter 26 for applying voltage for radio wave oscillation to the feeding points 24, 25 . The above-described door approach transmission and reception apparatus can be used in a door lock control apparatus where a search radio wave is emitted from a vehicle, a portable wireless device 10 receives the search radio wave, and returns an ID signal. An electrically driven door lock apparatus 40 is driven to unlock the door when the returned ID signal coincides with a registered ID signal. The search radio wave is irradiated from the slot antenna. Either of a transmitter 26 and a receiver 33 is selectively connected to the feeding points 24, 25 . By virtue of the above-described features, the emission and reception of radio waves is realized, and in the case of a door handle made of a metal, the number of parts for emission and reception of the radio waves are reduced.

Low-Loss NbTiN Films for THz SIS Mixer Tuning Circuits

Abstract: Recent results at 1 THz using normal-metal tuning circuits have shown that SIS mixers can work well up to twice the gap frequency of the junction material (niobium). However, the performance at 1 THz is limited by the substantial loss in the normal metal films. For better performance superconducting films with a higher gap frequency than niobium and with low RF loss are needed. Niobium nitride has long been considered a good candidate material, but typical NbN films suffer from high RF loss. To circumvent this problem we are currently investigating the RF loss in NbTiN films, a 15K Tc compound superconductor, by incorporating them into quasi-optical slot antenna SIS devices.

Annular slot-coupled dielectric resonator antenna

Abstract: An annular slot-coupled dielectric resonator antenna is investigated experimentally. As compared with the previous rectangular-slot version, the new configuration offers a much wider bandwidth of 18%. The return loss, radiation patterns, and antenna gain of the configuration have been measured and are discussed.

Tunable slot antenna with capacitively coupled slot island conductor for precise impedance adjustment

Abstract: A coaxial resonant slot antenna includes a flat rectangular conductive box having its top plate with a slot being defined therein, and a strip conductor disposed inside the box and electrically insulated from the box while high frequency or RF power is fed to the strip. An island conductor is provided in the slot for defining a capacitance between itself and the frame. This capacitance is rendered variable in value by use of a variable circuit.

Numerical optimisation of slot parameters for a concentric array radial line slot antenna

Abstract: Numerical slot design of a concentric array radial line slot antenna (CA-RLSA) with matching slots is proposed for small aperture antennas. In contrast to the previous design for large aperture RLSAs based upon continuous source model, parameters of discrete slots in the finite aperture are directly determined for uniform excitation. A remarkable efficiency of 85% and 82% is measured for 24 cm and 16 cm diameter antennas, respectively.