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Showing papers on "Slot antenna published in 1996"


Journal ArticleDOI
H. Iwasaki1
TL;DR: In this paper, a new, circularly polarized small-size microstrip antenna using a proximity coupled feed method is proposed, and 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.
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.

395 citations


Journal ArticleDOI
01 Apr 1996
TL;DR: In this article, the balanced antipodal Vivaldi antenna is presented, which incorporates an ultrawide bandwidth transition and overcomes the poor polarisation performance of the original Vivaldi form.
Abstract: The Vivaldi antenna, a form of tapered slot radiator, has been shown to produce good performance over a wide bandwidth, limited only by the traditionally used slotline to microstrip feed transition. The authors present a new antenna, the balanced antipodal Vivaldi, which incorporates an ultrawide bandwidth transition and overcomes the poor polarisation performance of the antipodal form. Good performance over a 1 to 40 frequency range has been obtained. The use of the antenna in a linear phased array has also been investigated using elements constructed on high permittivity substrate. Wideband wide angle scanning with good cross-polarisation levels is obtained.

265 citations


Journal ArticleDOI
Masaaki Nagatsu, Ge Xu, Masashi Yamage1, Masaaki Kanoh1, Hideo Sugai 
TL;DR: In this article, a large-planar (22 cm diam.) high-density ( ~2×1012 cm-3) plasma is produced in argon gas at 140 Pa by 2.45 GHz-1 kW discharges, using a microwave launcher of small slot antennas.
Abstract: A large-planar (22 cm diam.) high-density ( ~2×1012 cm-3) plasma is produced in argon gas at 140 Pa by 2.45 GHz–1 kW discharges, using a microwave launcher of small slot antennas. The two-dimensional distributions of optical emission intensities as well as microwave field intensities are measured near the plasma surface irradiated with microwaves. Both the optical emission and the microwave field clearly show stationary patterns of azimuthal mode m=3 and radial mode n=3 at higher pressures (140 Pa), while a mode change to m=6 and n=2 is observed at lower pressures (44 Pa). These patterns are attributed to the excitation and absorption of standing surface waves near the cutoff layer.

111 citations


Journal ArticleDOI
TL;DR: In this paper, the up-scaled discharge architecture for remote processing, suppressing the direct microwave heating and ion bombardment is proposed, and the scaling rules and limitations of upscaling are discussed.
Abstract: In slot antenna (SLAN) type plasma sources the microwave power is coupled from an annual waveguide (ring cavity) through equidistantly positioned resonant coupling slots into the plasma chamber made of quartz. The symmetrical power distribution and the surface wave at the plasma - quartz interface allows large-area plasma generation. Three plasma sources with 4, 16 and 66 cm quartz tube diameter (ring cavities with 4, 10 and 30 coupling slots respectively) are compared. The ECR versions of them are also considered. The ignition performance and operation pressure range are presented. Plasma parameters (ion concentration, electron temperature) and their radial and axial distributions are shown. The computation tools used for the design of sources with different dimensions are described. The scaling rules and limitations of up-scaling are discussed. These are plasma inhomogeneity due to diffusion and recombination processes, thermal load of the microwave components, and thermal and mechanical load of the plasma chamber and substrates. The up-scaled discharge architecture for remote processing, suppressing the direct microwave heating and ion bombardment is proposed.

90 citations


Journal ArticleDOI
TL;DR: In this paper, single and dual-polarized dielectric lens-supported slot-ring antennas have been developed for operation at millimeter-wave frequencies, and the measured antenna patterns agree well with theoretical results and have symmetric main beams, low sidelobe levels, low cross polarization (<-20 dB), and 27 dB directivity.
Abstract: Single- and dual-polarized dielectric lens-supported slot-ring antennas have been developed for operation at millimeter-wave frequencies. The antennas are fed with a coplanar waveguide (CPW) to be compatible with uniplanar mixers and low-noise amplifiers, and the feedline is shown to have a minimal effect on the antenna performance. The measured antenna patterns agree well with theoretical results and have symmetric main beams, low sidelobe levels (<-15 dB), low cross polarization (<-20 dB), and 27 dB directivity. A 2/spl times/2 array of single-polarized slot-ring antennas for monopulse applications demonstrates excellent patterns at 94 GHz with -3 dB crossover power levels in both elevation and azimuth scans. The dual-polarized slot ring antenna patterns are nearly identical to those of the single-polarized antenna, and two-port isolation is as low as -25 dB. The dielectric lens-supported slot-ring antenna is an excellent candidate for compact, low-cost millimeter-wave systems with fixed or variable polarization capabilities.

87 citations


Patent
29 Oct 1996
TL;DR: In this paper, an electrically short meandered-slot antenna with a plurality of switch-selected resonant frequencies is described, where the switches are powered inductively and selectively at individual frequencies outside the operating band of the 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.

83 citations


Journal ArticleDOI
TL;DR: In this paper, a planar, wideband feed for a slot spiral antenna is presented and tested at VHF frequencies, which is more attractive for conformal applications than most traditional printed spiral antenna designs.
Abstract: A new planar, wideband feed for a slot spiral antenna is presented and tested at VHF frequencies. Radiation pattern measurements are presented to demonstrate the performance and usefulness of this feed. In contrast to most traditional printed spiral antenna designs, the one presented here incorporates a completely planar balun and feed, making it more attractive for conformal applications.

72 citations


Patent
05 Sep 1996
TL;DR: In this article, a coaxial resonant slot antenna has been proposed to further reduce the dimensions of radio terminals incorporating such an antenna, and a method of fabricating such a antenna and a radio terminal has been described.
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.

71 citations


Journal ArticleDOI
TL;DR: The finite-difference time-domain (FDTD) method is applied to the analysis of CPW-fed folded-slot antennas, yielding antennas with a broadband 50 /spl Omega/ input impedance.
Abstract: Folded slot antennas are attractive for active arrays due to relatively large bandwidth, fabrication simplicity, and ease of integration with devices. Currently, there is little design information for these antennas, especially on thin substrates. The finite-difference time-domain (FDTD) method is applied to the analysis of CPW-fed folded-slot antennas. The paper describes the problems encountered in the analysis, compares the theoretical results and measured data, and provides some design information for folded slots. In addition, it explores the manipulation of input impedance through the use of additional slots, yielding antennas with a broadband 50 /spl Omega/ input impedance.

69 citations


Patent
03 Sep 1996
TL;DR: In this paper, an optically-transparent electrically-conductive solar central coating was used to reduce transmission in at least a part of the solar energy range in a vehicle.
Abstract: A motor vehicle, especially a passenger vehicle, has a metallic body provided with a window opening receiving an antenna window. The antenna window has inner and outer panes bonded together by a bonding layer with an optically-transparent electrically-conductive solar central coating reducing transmission in at least a part of the solar energy range. At least one edge of the window is left free from the coating and in this region a slot antenna is formed. At least at one additional edge, the coating runs to that edge and is overlapped by the framing portion of the vehicle body and is coupled with a high-frequency coupling to the coating.

61 citations


Patent
13 Nov 1996
TL;DR: In this paper, the antenna assembly comprises a plurality of antennas in first, second, and third antenna groups physically disposed along a backplane, the backplane having a longitudinal axis along which the antennas are disposed, and a phase adjustment mechanism disposed electrically connected between the second first and third antennas groups, such that adjustment of the phase adjustment mechanisms results in variation of the vertical radiation pattern downtilt angle.
Abstract: An antenna assembly having an operating frequency and a vertical radiation pattern with a main lobe axis defining a downtilt angle with respect to the earth's surface. The antenna assembly comprises a plurality of antennas in first, second, and third antenna groups physically disposed along a backplane, the backplane having a longitudinal axis along which the antennas are disposed, and a phase adjustment mechanism disposed electrically connected between the second first and third antenna groups, such that adjustment of the phase adjustment mechanism results in variation of the vertical radiation pattern downtilt angle.

Patent
23 Dec 1996
TL;DR: In this paper, an integrated microstrip feed (16) was used to provide a balanced feed to the slot spiral and a shallow reflecting cavity was included to limit the spiral radiation to one direction.
Abstract: A slot spiral (18) antenna with a planar integrated balun and feed. The slot spiral is produced using standard printed circuit techniques and comprises a dielectric substrate having a conductive layer which is etched to form the radiating slot spiral. An integrated microstrip feed (16) is included to provide a balanced feed to the slot spiral. Impedance matching is preformed between the microstrip feed and the slotline of the slot spiral to maximize energy transfer. A shallow reflecting cavity is included to limit the spiral radiation to one direction. The described antenna apparatus provides a simple, broadband spiral antenna suitable for incorporating into the skin of a moving vehicle. A covering layer may act as a dielecric lens. Outer parts of the slot spiral may be covered with a lossy absorber for termination. The feed point may be off-center with respect to the spiral.

Patent
23 Aug 1996
TL;DR: In this paper, a horlogical piece intended to be worn on the wrist including either a dipole antenna (4) or a slot antenna (30, 40) and a first case (5) comprising organs (7, 8, 10) for displaying the time, and a micro receiver (6).
Abstract: Horlogical piece intended to be worn on the wrist including either a dipole antenna (4) or a slot antenna (30; 40) and a first case (5) comprising organs (7, 8, 10) for displaying the time, and a micro receiver (6). The horlogical piece further comprises a second case (2) intended to receive the first case (5) such that the exterior surface of the first case and the interior surface of the second case defined a mounting slot (25). The antenna (4; 30; 40) comprises a dielectric substrate (13; 33; 43), and at least one printed circuit conductive element (11, 12; 31; 41) fixed the substrate (13; 33; 43). In addition, the antenna (4; 30; 40) is located in the mounting slot (25) such that it is wound around the first case (5).

Journal ArticleDOI
TL;DR: In this article, an annular slot on triplate feed is discussed which is suitable for use with vehicular mobile satellite systems, and the slot is excited in a higher order mode and circularly polarised to give a conical radiation pattern.
Abstract: An annular slot on triplate feed is discussed which is suitable for use with vehicular mobile satellite systems. The slot is excited in a higher order mode and circularly polarised to give a conical radiation pattern. The slot can operate on a high dielectric base and a superstrate improves the gain.

Journal ArticleDOI
TL;DR: A radial line planar monopulse antenna is proposed which gives an understanding of why the monopulse patterns can be synthesized, and a simple and effective theory is presented about a realization of uniform-aperture field distribution.
Abstract: In recent years, mobile satellite communications have been growing rapidly. Monopulse tracking operations for beam pointing to the satellite are often employed for those systems which, in general, require rather severe EIRP and G/T specifications. Thus, the development of a monopulse antenna with a good antenna efficiency is of great interest. A radial line planar monopulse antenna is proposed. An analysis of the probes in a radial line has been carried out which gives an understanding of why the monopulse patterns can be synthesized, and a simple and effective theory is presented about a realization of uniform-aperture field distribution. The antenna has been fabricated and the radiation characteristics have been measured which supports the theory as well as verifies the capability of the antenna for the monopulse tracking operation.

Journal ArticleDOI
TL;DR: In this paper, the electromagnetic field of dipole antennas for interstitial microwave hyperthermia is investigated using a finite integration algorithm program, which is applied to conventional, clinically used applicators and also used for the improvement and optimization of sophisticated applicators.
Abstract: The electromagnetic field of dipole antennas for interstitial microwave hyperthermia is investigated using a finite integration algorithm program. The numerical method is applied to conventional, clinically used applicators and is also used for the improvement and optimization of sophisticated applicators, e.g., in a triaxial technique. Simulations of the frequency dependent impedance match, the E-field and the specific absorption rate (SAR) distribution of different applicators immersed in a muscle phantom are presented and compared with measurements. Moreover, results for arrays of two and four applicators are given. The field simulation allows one to study the effects at the various discontinuities of the applicator-catheter-tissue system and gives a better understanding of known phenomena.

Journal ArticleDOI
TL;DR: In this article, the mutual coupling between the slot antennas in an array environment is calculated for a three-layer high-low-high permittivity combination, and the theoretical results are verified with measurements.
Abstract: Coplanar wave (CPW)-fed slot antennas printed on multilayer dielectric substrates are numerically analyzed using a full-wave integral equation technique and the method of moments. The Green's function is derived with an iterative formulation. Results obtained with a simplified and a rigorous model of the feeding CPW lines are compared. The mutual coupling between the slot antennas in an array environment is calculated for a three-layer high-low-high permittivity combination. The theoretical results are verified with measurements.

Journal ArticleDOI
TL;DR: In this article, a planar aperture coupled microstrip antenna for 77 GHz is demonstrated for the first time, where the antenna patches are suspended on a thin dielectric SiN/sub x/ membrane on GaAs substrate.
Abstract: Planar aperture coupled microstrip antennas for 77 GHz are demonstrated for the first time. As far as possible standard GaAs monolithic microwave/millimeter-wave integrated circuit (MMIC) technology is used to realize the antennas. The antenna patches are suspended on a thin dielectric SiN/sub x/ membrane on GaAs substrate. Therefore a novel plasma-enhanced chemical vapor deposition (PECVD) process step for the fabrication of the membranes is developed and described. The single antenna patches are coupled to a microstrip line through an aperture in the ground metallization. The method of moments in spectral domain is applied to design the patches. The feed network of a 3/spl times/1 antenna array for homogeneous excitation is simulated and optimized with a microwave design system (MDS). From reflection measurements the operation frequency of this triple patch antenna is determined to be 77.6 GHz. The farfield antenna characteristics are measured in an anechoic chamber, showing good agreement between simulated and measured results and a co- to cross-polarization isolation better than 30 dB.

Journal ArticleDOI
TL;DR: In this paper, a moment method (MM) analysis is performed using a cosine basis function for each slot and the Galerkin method, which can be extended to incorporate thickness of the metal plate supporting the slots.
Abstract: Two methods for the analysis of slot-array radial-line antennas are presented. A moment method (MM) analysis is performed using a cosine basis function for each slot and the Galerkin method. The analysis can be extended to incorporate thickness of the metal plate supporting the slots. Closed form formulas are also derived to model the slot antenna as a multiport network. This model allows a faster antenna analysis when a large number of slots are present. The multiport model has been validated with the MM analysis in a two-slot case and through the measurements of a more complex antenna problem. © 1996 John Wiley & Sons, Inc.


Journal ArticleDOI
TL;DR: In this article, the effects of the cover-layer thickness, bias-field strength, and the existence of both ordinary and extraordinary waves on the switchable antenna properties are discussed.
Abstract: Switchable antennas consisting of microstrip elements with an in-plane biased ferrite cover layer are introduced. Their radiation and radar cross section (RCS) properties are examined through a full-wave moment-method analysis. For microstrip antennas with a ferrite cover layer, the presence of a decaying extraordinary wave in the ferrite layer can reduce or prohibit incident fields from reaching the antenna resulting in significant RCS reduction. For antenna radiation, most of the power will be converted into magnetostatic waves and little radiates into the air. Under such circumstances, the antennas are "off," in the sense that they are effectively absent as radiators or scatterers. The aim of this paper is, through the use of an accurate full-wave analysis, to investigate the properties of the switchable microstrip antennas. Both the cases of strip dipoles and rectangular patches are analyzed. The effects of the cover-layer thickness, bias-field strength, and the existence of both ordinary and extraordinary waves on the switchable antenna properties are discussed.

Journal ArticleDOI
TL;DR: In this article, a slot-fed patch antenna with voltage controlled tuning varactors is used to adjust the resonant frequency in a large frequency band (up to 1 GHz) while the impedance matching remains good.
Abstract: The authors present an original application of a slot-fed patch antenna. Voltage controlled tuning varactors are connected across the radiating edges of the patch antenna and the resonant frequency can be adjusted in a large frequency band (up to 1 GHz) while the impedance matching remains good. Results based on the transmission line model are compared with measurements.

Journal ArticleDOI
01 Jul 1996
TL;DR: In this article, the insertion loss and antenna factor of the NPL calculable dipole antenna with an uncertainty as low as /spl plusmn/0.1 dB were derived from a comparison of measured and predicted insertion loss between two antennas.
Abstract: Using a pair of calculable standard dipole antennas above a large specially constructed ground plane it is demonstrated over the frequency range of 30-500 MHz that the antenna factor can be attributed to the standard antenna with an uncertainty as low as /spl plusmn/0.1 dB. The uncertainty is derived from a comparison of measured and predicted insertion loss between two antennas. The insertion loss and antenna factor of the NPL calculable dipole antenna are calculated by two different methods. The results agree to better than /spl plusmn/0.05 dB. By the correct choice of equipment and operating methods it is possible to obtain an agreement between measured and predicted values of insertion loss to better than /spl plusmn/0.2 dB. A detailed analysis of uncertainties is given. At 1 GHz the difference increased to /spl plusmn/0.8 dB because of the large size of the feed arrangement relative to the dipole length. Whereas in the past an accurate prediction of the antenna factor of resonant dipoles has been claimed, here it is shown that similar accuracy can be achieved for bandwidths of 200%. This makes it possible to use dipole antennas as broadband calculable standards with which to accurately calibrate broadband antennas and evaluate the performance of EMC test sites.

Proceedings ArticleDOI
17 Jun 1996
TL;DR: In this paper, a large-scale W-band focal plane array (FPA) for passive radiometric imaging application is proposed, which consists of a single direct detection MMIC which is a high gain, wide bandwidth switched LNA with integrated Schottky barrier diode detector.
Abstract: This paper discusses the development of a large scale W-band focal plane array (FPA) for passive radiometric imaging application. The goal is to develop a 40/spl times/26 (1040-pixels) FPA to cover 15/spl deg//spl times/10/spl deg/ instantaneous field-of-view. Each receiver consists of a single direct detection MMIC which is a W-band high gain, wide bandwidth switched LNA with integrated Schottky barrier diode detector. A 1/spl times/4 FPA module, employing linearly tapered slot antenna, is used as the basic building block for the FPA. Typical receiver temperature sensitivity is 0.4 K with 10 ms integration time. For the first time, an automated assembly process is used to produce W-band MMIC modules in large volume.

Proceedings ArticleDOI
21 Jul 1996
TL;DR: In this article, the effects of the tapered profile and the curvature of the mounting structure on tapered slot antennas were experimentally investigated and the results indicated that both effects have significant impacts on the gain, beamwidth, bandwidth and cross-polarised level of the antenna.
Abstract: The effects of the tapered profile and the curvature of the mounting structure on tapered slot antennas were experimentally investigated. Results indicate that both effects have significant impacts on the gain, beamwidth, bandwidth and cross-polarised level of the tapered slot antennas. These results are presented and discussed.

Journal ArticleDOI
TL;DR: In this article, an oscillating slot loop antenna working at 4.02 GHz is realized with a low cost GaAs MESFET and a conductor backing is used to obtain a unidirectional radiation pattern.
Abstract: An oscillating slot loop antenna working at 4.02 GHz is realised with a low cost GaAs MESFET. A conductor backing is used to obtain a unidirectional radiation pattern.

Journal ArticleDOI
TL;DR: In this paper, a new conformal antenna for hand held mobile telephones is proposed with a modified method of moments, which enables an accurate modelling of the slot and of any case structure to calculate input impedance as well as electric and magnetic near and far fields taking the influence of the user's head and hand into consideration.
Abstract: A new conformal antenna for hand held mobile telephones is proposed. The slot antenna is investigated with a modified method of moments. It enables an accurate modelling of the slot and of any case structure to calculate input impedance as well as electric and magnetic near and far fields taking the influence of the user's head and hand into consideration. The interaction with the human body can significantly be reduced.

Journal ArticleDOI
TL;DR: In this article, double probe axial distribution measurements of the electron density and temperature are performed for argon, helium and nitrogen discharges in a power range from 120 to 1200 W and a pressure range from 10 to 150 Pa.
Abstract: A new slot antenna concept allows the generation of large volume 2.45 GHz discharges. The microwave power is coupled from an annular waveguide (ring cavity) through ten equidistantly positioned resonant coupling slots into the quartz plasma chamber. Langmuir double probe axial distribution measurements of the electron density and temperature are performed for argon, helium and nitrogen discharges in a power range from 120 to 1200 W and a pressure range from 10 to 150 Pa. Characteristic differences in the discharge behavior for the various gases are presented. With argon a surface wave at the plasma‐quartz interface can be excited, already at 200 W. The resulting plasma column can extend up to 450 mm in length along the tube with 160 mm diameter. The surface wave mode is identified as a m=5 mode by visual inspection of the plasma formation and by recording the azimuthal electric field distribution. In contrast to argon, for helium and nitrogen no surface wave generation for power levels up to 1200 W are observed. Within the investigated power range both gases show a diffusion controlled variation of the electron density. This is verified by fitting the axial density data to the time‐independent diffusion equation for helium and nitrogen and to a simplified surface wave model for argon.

Journal ArticleDOI
TL;DR: In this article, a slot antenna microwave plasma source is used for remote plasma deposition of scratch resistant films on polycarbonate substrates, where the monomer hexamethyldisiloxan is distributed 5-50 mm over the substrate positioned 5-25 cm from the separation grid.

Patent
03 May 1996
TL;DR: In this paper, a microstrip-fed cylindrical slot antenna is provided for better communication between an object and a satellite, which includes a first conductive coating, at least one slot disposed in the conductive coatings, and a feed line corresponding to each of the slots, the feed line crossing each respective slot and extending beyond the slot by a distance D.
Abstract: A microstrip-fed cylindrical slot antenna is provided for allowing better communication between an object and a satellite. The microstrip-fed cylindrical slot antenna comprises a cylindrical base member; a first conductive coating disposed on the cylindrical base member; at least one slot disposed in the conductive coating, the slot having a helical configuration about the cylindrical base member; and a feed line corresponding to each of the slots, the feed line crossing each respective slot and extending beyond the slot by a distance D.