Showing papers on "Slot antenna published in 1992"

Microstrip antennas

Abstract: Microstrip antennas have been one of the most innovative topics in antenna theory and design in recent years, and are increasingly finding application in a wide range of modern microwave systems. This paper begins with a brief overview of the basic characteristics of microstrip antennas, and then concentrates on the most significant developments in microstrip antenna technology that have been made in the last several years. Emphasis is on new antenna configurations for improved electrical performance and manufacturability and on advances in the analytical modeling of microstrip antennas and arrays. >

Millimeter-wave and terahertz integrated circuit antennas

Abstract: A comprehensive review of integrated circuit antennas suitable for millimeter and terahertz applications is presented. A great deal of research was done on integrated circuit antennas in the last decade, and many of the problems associated with electrically thick dielectric substrates, such as substrate modes and poor radiation patterns, have been understood and solved. Several antennas, such as the integrated horn antenna, the dielectric-filled parabola, the Fresnel plate antenna, the dual-slot antenna, and the log-periodic and spiral antennas on extended hemispherical lenses, which have resulted in excellent performance at millimeter-wave frequencies, are covered in detail. A review of the efficiency definitions used with planar antennas is included. >

Double-slot antennas on extended hemispherical dielectric lenses

Abstract: An investigation of the coupling efficiencies to a gaussian-beam of a double-slot antenna on a hyperhemispherical lens is presented. It is shown that both lenses couple equally well to an appropriate gaussian beam (about 80 percent). The radiation patterns of both lenses with a double-slot antenna are computed using the ray-tracing method. The experimental radiation patterns are presented and show close agreement to the theoretically computed patterns.

Quasi-optical slot antenna SIS mixers

Abstract: A quasi-optical SIS mixer designed for efficient radiation coupling is described. The mixer uses a twin-slot antenna which has the advantages of a good beam pattern and a low impedance. The radiation and impedance characteristics of the antenna were obtained from a moment-matched calculation. Tapered superconducting microstrip transmission lines are used to carry the radiation from the slot antennas to the tunnel junction. The effective impedance seen by the tunnel junction is quite low, about 4 Omega , which allows micron-size junctions to be used at 500 GHz. The mixers have been fabricated using Nb/Al-oxide/Nb tunnel junctions and a receiver noise temperature of 420 K (DSB) was measured at 490 GHz, which is the best yet obtained for a quasi-optical mixer at this frequency. The comparatively large junction area increases the mixer saturation power and allows strong suppression of noise from the Josephson effect by the application of a magnetic field of modest strength. >

Analysis, design, and measurement of small and low-profile antennas

Abstract: How to apply the moment method to wire antenna analysis evaluation of the basic performance of microstrip antennas key points in the design and measurement of microstrip antennas analysis of planar inverted-F antennas and antenna design for portable radio equipment design and analysis of small-aperture antennas design and measurement of small AM broadcasting antennas mutual coupling effects between antenna elements on antenna performance some considerations of small antenna measurements.

High-gain broadband V-shaped slot antenna

Abstract: A nonresonant, traveling-wave V-shaped slot antenna providing high gain and a broad bandwidth for coupling infrared radiation onto a detector. The V-shaped slot antenna includes a relatively thick dielectric substrate and a metallization layer formed on the substrate. The metallization layer includes a pair of slots positioned at an angle φ 1 to form a V-shaped slot. The slot angle φ 1 is equal to approximately twice the radiation angle ψ, which is defined as the arccos of v d /v s , where v s is the propagation velocity of the infrared radiation in the two slots and v d is the propagation velocity of the radiation in the dielectric substrate. At the slot angle φ 1 , the radiation in the two slots adds in phase to produce a single high-gain beam along the V axis.

Waveguide-fed parallel plate slot array antenna

Abstract: A novel planar antenna in which radiating slots are arrayed on one side of a square parallel plate waveguide and coupling slots occupy the other side is proposed. The antenna is excited via the coupling slots by a rectangular waveguide. In order to suppress unwanted reflections and to assure the purity of the transverse electromagnetic traveling-wave mode in the parallel plate waveguide, all the slots are arrayed in pairs. An X-band model antenna was fabricated, and uniform aperture illumination was demonstrated with 48% antenna efficiency. These results demonstrate the feasibility of antennas of this type. >

Millimeter wave antennas

Abstract: Major advances in millimeter-wave antennas have been made in recent years, in particular in two areas. A new class of leaky-wave antennas based on open millimeter waveguides has been proposed and investigated, and substantial progress has been achieved in integrated antennas where active and passive circuits, possibly in monolithic form, are combined with the radiating elements in one compact unit. Interesting developments have taken place also in a third group of millimeter-wave antennas, that of microstrip antennas and printed circuit antennas in general. An attempt is made to summarize these developments. >

A reflection cancelling slot set in a linearly polarized radial line slot antenna

Abstract: A radial line slot antenna (RLSA) is a high-gain and high-efficiency planar antenna. A linearly polarized RLSA (LP-RLSA) is attractive for applications of various subscriber radio systems. However, the slot arrangement for linear polarization gives rise to serious reflection from slots, which disturbs the normal antenna operation. A new LP-RLSA slot design is presented where reflection canceling slots are added to the conventional ones; four slots form one slot set as a unit radiator of linear polarization. The experiments confirm the design: the antenna return-loss is improved from -2 to -10 dB. Antenna efficiencies of 48 and 54% are measured for 400 and 600-mm phi antennas, respectively. This is the first report of the normal operation of LP-RLSAs. >

Multiport scattering analysis of general multilayered printed antennas fed by multiple feed ports. I. Theory

Abstract: A general solution is given for a class of printed antenna geometries composed of multiple dielectric layers or ground planes, radiating patches, dipoles, or slots, and an arbitrary configuration of multiple transmission lines proximity-coupled or aperture-coupled to the radiating elements. The solution uses a full-wave spectral-domain moment method approach, and a new generalized multiport scattering formulation to model the excitation from the multiple feed lines. This method treats infinite phased arrays as well as isolated elements. The general theory using the new multiport scattering formulation is elaborated, with details of the key analytical and numerical aspects. Considering the unified nature of the multiport scattering analysis, and its simplicity, this analysis is appropriate for computer simulation of a large variety of multilayered microstrip antennas involving radome layers, dual polarized feeds, proximity-coupled or aperture-coupled elements, multifeed stacked or parasitic patches, and several related configurations for integrated phased array applications. >

Multiport scattering analysis of general multilayered printed antennas fed by multiple feed ports. II. Applications

Abstract: For Part I, see ibid., vol.40, no.5, p.469-481 (1992). The general analysis of part I is applied to several practical geometries of multilayer/multifeed printed antennas. These examples include a dual-feed circularly polarized geometry; a stacked patch geometry; a stripline-aperture coupled geometry with a radome; an open-end proximity-coupled patch; and dipole and slot geometries inclined or perpendicularly coupled to different feedlines. Features of the selected geometries cover many practical aspects of multilayer integrated phased arrays. Experimental results for several geometries are compared with the analytical results to demonstrate the accuracy and versatility of the analysis used. Various design considerations for the use of these multilayered printed antenna geometries in integrated phase array applications are discussed. >

Transmission line analysis of nonlinear slot coupled microstrip antenna

Abstract: The transmission line method is used for the analysis of microstrip antennas fed by several nonlinear slots with ‘H’ shapes [see ref. 1] or new geometries ‘└┘’, ‘└┐’ and ‘└─’ types. This analysis allows the input impedance of nonlinear slot coupled microstrip antennas to be calculated for the four different structures. The theoretical results are in good agreement with experiments.

Characteristics of small-aperture, single-layered, radial-line slot antennas

Abstract: A radial-line slot antenna (RLSA) is a high-efficiency planar array. A double-layered radial line and uniform slot length have been adopted in conventional RLSAs. A single-layered RLSA is much simpler in structure, but the slot length must be varied to synthesise uniform aperture illumination. The authors propose theoretical methods for the slot design. The paper presents excellent characteristics of single-layered RLSAs of small sizes (0.25–0.60 m diameter) and confirms the design. These are now commercialised for 12 GHz band DBS reception.

Analysis of printed linear slot antenna using lossy transmission line model

Abstract: A model of the printed linear slot antenna using the lossy transmission line method is presented. The Cohn analysis is used to determine the characteristics of the slotline. The attenuation coefficient is numerically determined. Theoretical input impedances of offset-fed slots are compared successfully with experimental results given by other authors.

Method and apparatus for electromagnetic logging with two dimensional antenna array

Abstract: A two-dimensional array of slot antennas which can provide two-dimensional quantitative dielectric and conductivity images of formations in the region surrounding an earth borehole. The antennas are mounted in a wall-engaging member of a logging device that is moveable through the borehole. Selected ones of the antennas are energized at given times to transmit electromagnetic energy into the formations, the electromagnetic energy being received at other antennas for processing to obtain formation properties.

Non-planar linearly tapered slot antennas with balanced microstrip feed

Abstract: A nonplanar linearly tapered slot antenna (LTSA) has been fabricated and tested at frequencies from 8 to 32 GHz. The LTSA is excited by a broadband balanced microstrip transformer. An LTSA fed with this feed network exhibits very broad bandwidth extending from X-band to Ka-band with good impedance match and excellent radiation patterns. >

Stripline patch antenna with slot plate

Abstract: A stripline patch antenna having a slot plate which is capable of obtaining higher antenna gain, while reducing the loss due to the feed lines. The antenna includes at least one radiating element for transmitting and receiving radio waves; a feed line for transmitting signals to and from the radiating element; a dielectric substrate for supporting the radiating element means and the feed line means; a grounding conductor located below the dielectric substrate; and a slot plate located above the dielectric substrate, having a plurality of slots more numerous than the radiating element. The triplate substrate can be adapted to this antenna. A plurality of antenna units so constructed can be arranged in array such that at least one of the slots of each antenna unit is shared with a neighboring antenna unit.

Waveguide transition for flat plate antenna

Abstract: In a flat plate antenna, insertion loss is reduced significantly by providing an extensive waveguide structure at the back of the ground plane of the antenna. Depending on antenna size, the waveguide may feed the antenna at one or a plurality of points. According to a preferred embodiment, the transition from waveguide to stripline is made via a coaxial connection, with a quarter-wave transformation, including mode suppression walls to direct the energy more efficiently. Alternatively, a direct waveguide to stripline transition may be provided. The technique has wide applicability to a number of antenna designs, including single- and dual-polarization structures, and linear and circular polarization operation.

New techniques for exciting linearly tapered slot antennas with coplanar waveguide

Abstract: Two new techniques for exciting a linearly tapered slot antenna (LTSA) with coplanar waveguide (CPW) are introduced. In the first approach, an air bridge is used to couple power from a CPW to an LTSA. In the second approach, power is electromagnetically coupled from a finite CPW (FCPW) to an LTSA. Measured results at 18 GHz show excellent return loss and radiation patterns.

A simple transmission line model for narrow slot apertures having depth and losses

Abstract: A simple transmission line model is given to approximately represent a narrow slot aperture having depth when the conductivity of the conducting plane (and slot walls) is large but not necessarily infinite and when somewhat lossy gaskets are placed in the slot. Slot and gasket dimensions, in addition to the electrical parameters of the conducting plane and gasket, are restricted so that gasket- and wall-loss-effects only need to be included locally (near the slot cross section) and additionally so that the slot voltage is nearly constant locally (however diffusion into the depth of the slot is considered when very lossy gaskets are introduced). Normal incidence is emphasized since this is typically the most important case for slots that are not too long compared to the wavelength. The transmission line model is used to obtain simple approximate formulas for resonant quality factor, slot voltage, penetrant fields, and transmitted power. Low frequency quantities including magnetic dipole moments are also obtained. Gaskets with air gaps are considered and optimum choices for electrical parameters are discussed. >

Novel rotational characteristics of radiation patterns of chirostrip dipole antennas

Abstract: We present certain novel characteristics of the radiation pattern of a chirostrip dipole antenna which consists of a short horizontal dipole antenna on a grounded chiral substrate. Chiral materials are characterized by constitutive relations D = ϵeE + iϵcB and H = B/μc + iϵeE. In our theoretical analysis we show that the radiation pattern of a simple chirostrip horizontal dipole undergoes a rotation around the axis normal to the substrate and that this rotation depends on the value of the chirality iϵe. Applications of this novel antenna are mentioned.

348-GHz endfire slotline antennas on thin dielectric membranes

Abstract: Tapered slotline endfire antennas, of the broken linearly tapered type, have been fabricated on 1.7- mu m-thin SiO/sub 2/-Si/sub 3/N/sub 4/ ( epsilon /sub r/=4.5) membranes. Antenna patterns in the E-, H-, D-, and D-cross planes have been measured at the design frequency of 348 GHz, with bismuth microbolometer detectors. The antennas have approximately 12-dB directivity, and the -10-dB beam widths are 50 degrees and 56 degrees in the E- and H-planes, respectively. The 348-GHz measurements have been compared with model measurements at 45 GHz, and show good agreement. >

Single-arm spiral slot antenna fed by a triplate transmission line

Abstract: A spiral slot antenna consisting of a single arm is etched into the upper plate of a triplate transmission line. Power on a feed strip line located between the upper and lowe plates of the triplate is electromagnetically coupled to the spiral slot. The configuration of the spiral slot is optimised for radiation of a circularly polarised wave. An array antenna consisting of spirals slots, to which a pair-element technique is applied, shows wideband characteristics for the return loss and axial ratio.

Single shaped reflector antennas for broadcasting satellites

Abstract: For future direct broadcasting satellites in Japan, precisely contoured beam antennas will be required for onboard antennas. Single shaped-reflector antennas are suitable for that purpose, since they do not need complex feed networks. However, in a previous study, discontinuities in the reflector surface were observed. The problem of the discontinuity was circumvented in this work and the shaped reflectors were successfully designed to produce contoured beams for covering the Japanese islands for the downlink and feederlink antennas. The downlink antenna was fabricated, and the radiation pattern was verified by measurement. The radiation pattern meets the radio regulations imposed on the onboard antenna, such as sidelobe and cross-polarization characteristics. >

A waveguide-fed parallel plate slot array antenna

Abstract: The authors propose an array in which a plane TEM (transverse electromagnetic) wave is excited in a parallel plate waveguide by a rectangular waveguide through feed slots cut in a back conductor. Its radiating part consists of an upper conductor plate in which a slot pattern has been etched. The configuration is suitable for linear polarization and dual-polarization use. The concept of a slot pair is adopted to suppress reflection and to maintain traveling wave antenna operation, which is confirmed by experiments. TEM plane wave excitation in the parallel plate waveguide has been confirmed, and the uniform aperture field distribution has been realized at the design frequency. >

40 GHz quasi-optical second harmonic spatial power combiner using FETs and slots

Abstract: FET oscillators integrated with slot radiators are used for constructing quasi-optical second-harmonic spatial power combiners. Double-oscillator power combiner circuits with a strongly coupled structure generated the 40-GHz second-harmonic frequencies. The radiation patterns of the double-oscillator power combiners are also discussed. Through the antenna patterns obtained one can also find information on the phase relationship between the oscillators. By controlling the phases on the slots, it was possible to obtain the Delta pattern for the 19-GHz fundamental and the Sigma pattern for the 40-GHz second harmonic. >

High-temperature superconductor antennas : utilization of low rf losses and of nonlinear effects

Abstract: The low radio frequency (r.f.) losses in epitaxial HTS thin films allow the realization of novel antenna structures which have to be excluded in conventional antenna techniques with normal conductors because of the highly reduced radiation efficiency. Thus, the design of miniaturized but nevertheless highly efficient antennas down to a lower limit determined by both the required order of radiation pattern and the frequency bandwidth becomes possible. For a bandwidth of more than about 1%, a considerable margin for a size reduction below the “critical size” is restricted to the case of electrically small antennas and of superdirective antennas with a relatively low order of the radiation pattern, e.g. antennas with a beam of less than 15 dB maximum gain. If the size approaches the lower limit, the antennas show a sharp bandpass frequency response. This is demonstrated by means of experimental results for a novel HTS meander antenna. These bandpass characteristics can be utilized in compact multiport antenna systems in order to decouple subantennas for adjacent frequency bands. Besides the low losses in HTS's, their nonlinear properties can be used in order to realize current-controlled HTS switches for antenna systems.

Polarization-universal radial line slot antenna

Abstract: A polarization-universal radial line slot antenna has a slot plate formed with numerous slots, a frame, and a partition plate interposed between the slot plate and the frame to form an upper layer waveguide and a lower layer waveguide. A pair of first and second feeding devices are provided in a central portion of the antenna. The first feeding device has a first matching member protruding into the upper layer waveguide for feeding thereto a radio wave diverging from a center to a periphery so that a left-hand circular polarized wave is emitted from the slots. The second feeding device has a second matching member for feeding a radio wave which passes through the lower layer waveguide and then converges from a periphery to a center of the upper layer waveguide so that a right-hand circular polarized wave is emitted from the slots. Consequently, the single antenna can concurrently transmit or receive the right-hand and left-hand circular polarized waves.

Full wave analysis for the equivalent circuit of an inclined slot on a microstrip ground plane

Abstract: The problem of a radiating slot on the ground plane of a microstripline is solved using the spectral domain approach. The equivalent circuit for the configuration is obtained, and the elements are determined using the integral transformation techniques. Effects of various parameters, such as slot dimensions and inclination with the feedline, are studied. Results are compared with measurements, and reasonable agreement is obtained. The results and the approach should find useful applications in integrated circuits and aperture-coupled patch antennas. >

Loss-bandwidth product for frequency selective surfaces

Abstract: Measurements of the transmission/frequency responses of slot arrays embedded centrally in dielectric layers of various thicknesses show an inverse relationship between the 6 dB width of the transmission band and passband loss. For er = 4.6, tan δ = 0.02 the losses exceed 1 dB for bandwidths below about 25%. A computer model identifies absorption in the dielectric as the main source of the loss.