Showing papers on "Slot antenna published in 1995"

Single-layer single-patch wideband microstrip antenna

Abstract: A coaxially-fed single-layer single-patch wide-band microstrip antenna in the form of a rectangular patch with a U-shaped slot is discussed. Measurements showed that this antenna can attain 10-40% impedance bandwidth without the need of adding parasitic patches in another layer or in the same layer.< >

Spherical antenna pattern(s) from antenna(s) arranged in a two-dimensional plane for use in RFID tags and labels

Abstract: The present invention introduces an RFID system that comprises a two-dimensional antenna configuration having a dipole in combination with a loop antenna or a second dipole with their dipole axes at approximately a 90° angle to one another The pattern of two dipole antennas combined with the pattern of a single loop antenna, allows the sequential combination of the patterns to represent a nearly spherical antenna pattern in three dimensions, while the antennas reside in a two-dimensional plane The presence of multiple antennas also allows for a method to switch among the multiple antennas to find the antenna or combination of antennas that create(s) the strongest RF communication link thereby enabling more efficient transmitted power or more directional reception coverage Improving efficiency can be further improved by taking this concept one step further by adding multiple antennas into the interrogator unit Now the possibility exists whereby the best RF communication possible can be established between the interrogator and transceiver units by switching to the best antenna combination that would most efficiently pass an RF signal between the interrogator and the transceiver before and after which any of the antennas are now free to be used for trickle charging the chargeable battery cell(s) that reside in the transceiver unit

Theory and experiment of an aperture-coupled hemispherical dielectric resonator antenna

Abstract: A hemispherical dielectric resonator (DR) antenna using aperture coupling for excitation is studied both theoretically and experimentally. The reciprocity method is used to formulate the problem. The exact magnetic field Green's function due to the equivalent magnetic current in the slot is derived rigorously, and it is presented in a form which can be evaluated very efficiently. Moment method is used to solve the magnetic current from which the input impedance of the antenna configuration is obtained. The equivalent radius of the slot is used so that simple formulae developed for the cylindrical dipole can be applied directly. The effects of the slot's length, the slot's position, and the slot's width on the broadside TE/sub 111/ mode input impedance are studied, and reasonable agreement between theory and experiment is obtained. >

Design and Characterization of Two-Junction Tuning Circuits for Submillimeter SIS Mixers

Abstract: We report on the continuing development of submillimeter quasi-optical slot antenna SIS mixers which use two-junction tuning circuits [1]. The mixers use 10 kA/cm2 Nb/Al-Oxide/Nb junctions and Nb wiring, and have generated DSB receiver noise temperatures around 5hv/kB to 700 GHz, and 16hv/kB (620 K) at 798 GHz. We present Fourier-transform spectrometer (FTS) measurements and heterodyne measurements on several such devices. In general, the measured response at frequencies below the gap of Nb is in good agreement with the predicted performance. Introduction SIS mixers with Nb-trilayer tunnel junctions offer excellent performance at frequencies below 800 GHz, and should perform competitively at frequencies as high as 1.4 THz [2-5]. Our goal is to develop a suite of ultra-low-noise SIS mixers which cover frequencies from = 400 GHz to more than I THz. At frequencies below the Nb gap (< 700 GHz), existing devices perform quite well [6], but further improvements in noise temperatures remain important. In addition, it is quite useful to be able to predict device performance given the design parameters. One can then optimize the device design for a particular frequency band, and confirm that we indeed understand the physics of the device. Progress in the design and operation of devices in this frequency range is presented below. At frequencies above the Nb gap, RF photons can break Cooper pairs, resulting in greater signal loss and higher receiver noise temperatures. The loss is particularly important in the slender microstrip lines used to resonate the junction capacitance and to transform the antenna impedance down to the RF junction impedance. However, the actual coupling of radiation into Nb junctions above the gap should still be reasonably efficient -more than 30% at 800 GHz [7]. In addition to RF loss, one is also affected by increased dispersion at frequencies near the gap. The Nb microstriplines have therefore been carefully designed to ensure the desired bandpass is achieved. We demonstrate for the first time that all-Nb SIS receivers can have substantially better performance than GaAs Schottky receivers for the astronomically important CI ( P2 — P 1 ) and CO (7-6) transitions near 810 GHz. Receiver Configuration Since waveguide mixers become difficult to construct at short submillimeter wavelengths, we have adopted a quasi-optical approach. Here, lenses take the place of waveguide horns, and the incoming radiation is collected by a planar antenna on the SIS mixer substrate [8]. This offers several other advantages, such as on-chip broad-band silt a SS 114 SSE WA Wa Sta MX Dewar 120 Mylar Window SIS Mixer 295 IQ 77 K Mylar Load Bearnsplitter ICI 1= NZ IC =1 HEN1T Amplifier Polyethylene Lens

Printed-circuit crossed-slot antenna

Abstract: A printed circuit cavity-backed crossed-slotted conductive element having two legs of each slot coupled by stripline feeders to a radio communications device. The feeders supply the radio frequency signal with a 180 degree phase shift in order to cancel cross-coupling from one leg to another around the intersection. The conductive element and the stripline feeders are mounted on separate substrates which are attached together with other elements to provide shielding and mechanical protection. The crossed-slot design reduces space and structure required for a mobile application while achieving good performance. When mounted in an array, the crossed slot antennas may be directionally tuned to a specific satellite/frequency/direction via pin diode phase shifters.

Radiation of printed antennas with a coplanar waveguide feed

Abstract: This paper presents an analysis of conductor-backed aperture antennas with multilayered substrate. These printed antennas are fed by a coplanar waveguide (CPW). The theoretical approach taken is to develop an integral equation over the aperture region and apply Galerkin's procedure in the spectral domain. The properties of printed antennas with a CPW feed are characterized. Numerical results include the scattering parameters, antenna pattern, and radiation efficiency. The reflection coefficient, input impedance, and far-field pattern are also compared with measurements and good agreement is observed. >

Double C-patch antennas having different aperture shapes

Abstract: Double C-patch antennas having different aperture shapes are experimentally investigated and reported. The effect of different design parameters on the performance of the antenna is studied and presented. The advantages of such antennas over the conventional rectangular microstrip antennas are explained.

Slot antenna arrangement for portable personal computers

Abstract: An antenna arrangement is provided in which a slot antenna is attached to the surface of an equipment case made of a dielectric material, there being provided also a ground plane spaced a small distance apart from the case and behind the antenna. The equipment may be a personal computer, e.g. a notebook computer, and the antenna, which may take the form of a copper foil, may be attached to the lid of the computer by an adhesive on its rear surface. The ground plane may, in this case, take the form of an existing display backplane. The invention provides for the realization of a compact antenna arrangement due to the effect of the case dielectric on the effective electrical length of the slot antenna.

Center-fed grid array antennas

Abstract: Single- and double-layer grid array antennas are numerically investigated. A radiation beam normal to the antenna plane is realized by using appropriate configuration parameters. The difference of the gains between the upper-fed and lower-fed grid arrays is very small (0.5 dB over a frequency range of 12.5 to 12.75 GHz).

Dual frequency cavity backed slot antenna

Abstract: A dual frequency cavity backed slot antenna and method of tuning the antenna, wherein the antenna comprises a plurality of stacked layers including a layer having a substrate with an accessible surface, the surface including thereon a continuous slot, first electrically conductive metallization disposed within the slot and extending to the slot, second electrically conductive metallization disposed external to the slot and at least one pair of frequency adjusting devices, one such device associated with the first metallization and the other device associated with the second metallization. The device pairs are either a foil and a tab, a pair of foils or a pair of indentations, one in each of the metallizations.

Low-noise slot antenna SIS mixers

Abstract: We describe quasi-optical SIS mixers operating in the submillimeter band (500-750 GHz) which have very low noise, around 5 h/spl nu//k/sub B/ for the double-sideband receiver noise temperature. The mixers use a twin-slot antenna, Nb/Al-Oxide/Nb tunnel junctions fabricated with optical lithography, a two-junction tuning circuit, and a silicon hyperhemispherical lens with a novel antireflection coating to optimize the optical efficiency. We have flown a submillimeter receiver using these mixers on the Kuiper Airborne Observatory, and have detected a transition of H/sub 2//sup 18/O at 745 GHz. This directly confirms that SIS junctions are capable of low-noise mixing above the gap frequency. >

Multi-octave, low profile, full instantaneous azimuthal field of view direction finding antenna

Abstract: An antenna which comprises a plurality of spaced apart antenna segments (1-8) which are electrically isolated from each other and form a conical antenna structure, an insulator (9) disposed between each of the antenna segments, a plurality of conductors (11), each coupled to a different one of the antenna segments, for sampling a predetermined parameter at the associated antenna segment and a ground plane (10) normal to the axis of the conical structure. The antenna segments are substantially pie-shaped. In a second embodiment of the invention, the antenna segments are disposed on an electrically insulating sheet, each of the antenna segments being flared at the corner regions thereof (22) remote from the apex of the conical structure. The space between each of the segments is a slot, the slot operational as a slot antenna when the segments on opposing sides of the slot are excited 180 degrees out of phase.

Circular slot antenna

Abstract: A radio antenna for mounting in the lid of a water meter box and forming part of a remote meter reading system comprises an annular conductive plate and a circular conductive plate which are coaxial with and parallel to each other and spaced apart to define a slot, the circular plate serving as a ground plate. The antenna has an input in the form of a conductive pillar interconnecting the two members, with a drive input at a selected point along the length of the pillar and a second input on the ground plate. A variable tuning capacitance is disposed between the plates diametrically opposite the conductive pillar. The ground plate also serves for locating the lid in undergrowth or under snow using a metal detector.

A dual‐frequency antenna using a single patch and an inclined slot

Abstract: Results on a dual-frequency microstrip patch antenna fed by using an inclined slot in the ground plane of a microstrip line are described. The frequencies of operation are determined by choosing the dimension of the rectangular patch and by adjusting the inclination angle of the slot. The antenna is easy to construct and results obtained from an antenna designed to operate around 9 and 12 GHz are presented. © 1995 John Wiley & Sons. Inc.

Antenna formed of multiple dielectric substrates including shielded LC filter

Abstract: An antenna device has an antenna part and a filter part combined into a single unit. The antenna part has a radiating electrode formed on a surface of layered dielectric substrates and a grounding electrode formed inside the layered structure. The filter part is formed below the antenna part and includes shield electrodes, capacitor electrodes and coil electrodes. A feed point on the antenna part and an input section of the filter part are electrically connected to each other through a roughhole, and external electrodes are formed on side surfaces of the multi-layered structure of the dielectric substrates, connecting the grounding electrode of the antenna part and the output section of the filter part. A slot electrode having a slot formed therethrough and a strip line extending perpendicularly to the slot may be inserted between the radiating electrode and the grounding electrode of the antenna part.

A dielectric-loaded miniature antenna for microcellular and personal communications

Abstract: The barium titratitanate is used as a substrate for two microstrip antennas designed on 900 MHz and 1800 MHz bands, respectively The objective is to study the feasibility of miniaturization of the antennas used for microcellular and personal communications The resonant frequencies, input impedances, and VSWR have been measured to assess the achieved performance of this type of antenna

Low profile TEM mode slot array antenna

Abstract: A low profile slot antenna is provided which includes first and second oppositely disposed metallic plates with a dielectric layer disposed therebetween. An array of horizontal and vertical radiating elements are formed in the first metallic plate. An array of horizontal coupling slots and an array of vertical coupling slots are formed in the second metallic plate. The antenna further includes a planar feed network electrically coupled to the coupling slots. The feed network is connected to a conductive waveguide tube located at the central portion of the antenna. Orthogonal probes couple the waveguide tube to a transceiver. Accordingly, the slot antenna may operate to transmit and receive linearly polarized energy. The antenna may further include a polarization converter for converting between linear and circular polarization so as to allow for antenna operation with single or dual circular polarization energy. The polarization converter may include a pair of Meanderline polarizer sheets disposed above the metallic plates, or alternately may include use of a ninety degree hybrid coupler.

A uniplanar 90-GHz Schottky-diode millimeter-wave receiver

Abstract: A 90 GHz Schottky-diode receiver based on a double slot antenna fed by a coplanar-waveguide (CPW) transmission line is presented. The double slot antenna is placed on an extended hemispherical high-resistivity silicon substrate lens. The uniplanar receiver results in a 9.3/spl plusmn/0.3 dB measured SSB conversion loss at 88-90 GHz including antenna and IF circuit losses and a 1-dB loss due to the use of a nonoptimal matching cap layer at the silicon lens-air interface. The calculated conversion loss agrees very well with the RF measurements. The uniplanar double-slot antenna receiver is very small, less than 1.1/spl times/4 mm including the RF/IF filter, and is compatible with monolithic two- and three-terminal devices on GaAs substrates. The application areas are in millimeter-wave receivers for automotive systems, communication systems, and radiometric linear imaging arrays. >

Integrated uniplanar transition for linearly tapered slot antenna

Abstract: This paper presents the design, fabrication, and numerical modeling of two new uniplanar microstrip-to-coplanar strip (CPS) line transitions and a new variant of the linearly tapered slot antenna (LTSA). This new variant with an integrated uniplanar microstrip-to-coplanar strip line feed is called a V-LTSA. The advantages of these transitions in packaging and monolithic microwave integrated circuits (MMIC) integration are listed. The two transitions and the feed are modeled using finite difference time domain (FDTD) method. The overall agreement between the measured and modeled return-loss and insertion-loss characteristics of two back-to-back transitions is good. The resonance frequencies predicted by the FDTD method are within a few percentage points of the measurements. Furthermore, the V-LTSA with the feed is experimentally shown to have a wide return loss (/spl les/-10 dB) bandwidth, good radiation patterns, and low cross-polarization. The gain of the V-LTSA is 9 dB at the design frequency of 10 GHz. A proof-of-concept package to house the feed is experimentally evaluated and shown to have negligible effect on the antenna characteristics. This type of antenna readily integrates with MMIC packages in an array having a brick architecture. The V-LTSA has potential applications in phased arrays. >

Characterization of a slot antenna microwave plasma source for hydrogen plasma cleaning

Abstract: A new large volume microwave plasma source has been used for the production of a hydrogen plasma The source consists of an annular waveguide cavity with axial slots on the inner side which acts as a field applicator to sustain a plasma at 245 GHz The plasma is contained in a fused silica bell jar of 16 cm in diameter and 20 cm in height The distance between the slots corresponds to a waveguide wavelength The source is able to generate a highly dissociated (up to 90%) hydrogen plasma for cleaning purposes Stable operation of the plasma source is shown for a pressure range of 01–13 mbar and a power range of 600–2000 W The plasma can be ignited over the entire examined pressure range, and the power needed for discharge ignition is below 17 kW The minimum ignition power is 1050 W for a pressure of 07 mbar A double Langmuir probe and optical emission spectroscopy were used to characterize the hydrogen plasma as a function of microwave power, pressure, and position The results indicated a typical ion density of 15×1011 cm−3 which is an order of magnitude less than that obtained for argon under similar conditions The typical electron temperature is 25 eV for microwave power of 2 kW and pressure of 07 mbar

Analysis of a broadband slot-coupled dielectric-coated hemispherical dielectric resonator antenna

Abstract: Dielectric-coated hemispherical dielectric resonator (DR) antennas fed by a microstrip line through a coupling slot are analyzed. The broadside TE111 mode is studied, and the reciprocity theorem is applied in this analysis. In this case the dielectric-coated DR antenna can be viewed as a series load at the slot position as seen by the microstrip line. The impedance of this series load is calculated by using a Green's-function formulation, and the input impedance of the slot-coupled DR antenna can then be obtained using transmission-line theory. Numerical results for the input impedance are calculated and presented, and the antenna bandwidth is discussed. It is observed that the antenna bandwidth of a dielectric-coated DR antenna can be as high as two times that of a DR antenna without a coating.

Multi-slot 50-/spl Omega/ antennas for quasi-optical circuits

Abstract: CPW-fed multiple-slot antennas have been developed for active arrays and integrated antennas. This letter describes how the antenna can be engineered for a self-resonant 50-/spl Omega/ input impedance for various substrate parameters, and the concepts are verified using a three-slot antenna on /spl epsiv//sub r/=2.2 substrate and a five-slot antenna on /spl epsiv//sub r/=9.8 substrate. These antennas have been integrated directly with commercial MMIC gain block chips without any matching networks to create a quasi-optical amplifier array. >

Design considerations for dual polarized aperture-coupled microstrip patch antennas

Abstract: The paper discusses the design of aperture-coupled microstrip patch antennas for dual linear polarization with special emphasis on achieving a wide bandwidth and a high polarization isolation. The coupling behavior of crossed slot and offset slot designs are discussed and compared to each other. Several design examples for aperture-coupled antenna elements illustrate how the polarization isolation decreases as the bandwidth of the antenna elements is increased. A feeding concept for an 8/spl times/1 element subarray yielding a polarization isolation of larger than 45 dB is presented.

Handbook of Antennas for EMC

Abstract: Part 1 Introduction to antennas: requirements of an antenna for EMC main characteristics of an antenna. Part 2 Basic mathematics for EMC engineers: angles basic trigonometry powers, indices, and logarithms real and complex numbers scalars and vectors Fourier analysis and transforms parameters fundamental units and dimensions. Part 3 Antenna theory: unit vectors scalar and vector fields Maxwell's equations boundary conditions fields due to a radiating dipole power flux density for a plane wave wave impedance for a plane wave radiation resistance far field of antennas. Part 4 Antennas for frequencies below 1 MHz: mechanism of radiation near and far fields of antennas wave impedance difference between receive and transmit antennas small antennas baluns radiation power factor matching antennas effective length and effective height E field antennas H field antennas. Part 5 Antennas for frequencies between 1 MHz and 1 GHz: resonant monopoles discone cavitenna resonant and large dipoles folded dipoles triangular dipoles biconical Yagi-Uda frequency independent (FI) antennas log periodic antenna bilog helical antennas large and resonant loops double-ridged horns. Part 6 Antennas for frequencies above 1 GHz: band theory log spiral archimedes spiral microstrip planar spiral discone antenna double-ridged horns. Part 7 Calibration of antennas: gain calculation of gain antenna correction factor. Part 8 List of acronyms and abbreviations: useful tables and conversion factors.

Moment method analysis of a horizontally polarised omnidirectional slot array antenna

Abstract: An entire domain moment method analysis of an omnidirectional linear array antenna, in which the radiating elements are slot doublets in a rectangular waveguide, has been developed. A particular feature of the analysis is that direct computation of internal mutual coupling between broadwall slots on opposing walls has been incorporated. Numerical solutions are presented for the scattering properties of the slot doublets in both air-filled and dielectric-filled waveguides. The results are shown to be in good agreement with network analyser measurements.

Conformal low profile wide band slot phased array antenna

Abstract: A cavity-backed slot array antenna is provided which offers wide frequency bandwidth in a conformal structure and further offers forward horizon coverage and wide angle beam scanning. The slot array antenna has a plurality of cavity-backed slot arrays. Each array contains a plurality of conductive cavities and radiating slots. The conductive cavities have varying size length and width in accordance with a log-periodic scale and, some conductive cavities have a maximum constant width. The slots are preferably formed in a folded configuration extending along a substantial portion of the width of the conductive cavity and further extend along a portion of the length of the conductive cavity one or more times. For a conductive cavity at maximum width, the corresponding slots are further extended in the effective overall length so as to further extend the frequency bandwidth, while maintaining a compact antenna structure.

Traveling-wave feeder type coaxial slot antenna

Abstract: A traveling-wave feeder type coaxial slot antenna, comprising: a central conductor extending over a certain length; a cylindrical outer conductor coaxially surrounding the central conductor; and a plurality of slots provided in the outer conductor at a certain inclination angle, for instance 45 degrees, relative to a longitudinal axis of the outer conductor. This antenna can be conveniently fabricated from a commercially available coaxial cable. By suitable selection of the inclination angle of the slots and their mutual spacing, the antenna may be provided with a directivity directed to a desired elevation angle when mounted on a vertical wall to make is suitable for receiving radio wave signals from a satellite.

Mmic package assembly

Abstract: PURPOSE: To prevent an undesired high frequency signal from entering a package or from being emitted to the outside of the package by coupling the inside of the package, an antenna element and a transmission line with each other electromagnetically through the use of slot coupling. CONSTITUTION: A planar antenna 41e or a high frequency signal transmission line are formed to the rear side (outer lower face) of a package 3 containing an MMIC(monolithic microwave integrated circuit) 2 in an enclosing way and a ground conductor 41c provided with a rectangular slot section 41d is formed to the package 3. A microstrip line 2f is provided to the surface of the MMIC 2. The lengthwise direction of the slot section 41d is made orthogonal to the lengthwise direction of the microstrip line 2f. A high frequency signal is transmitted by electromagnetic coupling a planar antenna 41e or a high frequency signal transmission line with the microstrip line 2f via the slot section 41d. COPYRIGHT: (C)1996,JPO

A planar quasi-optical mixer using a folded-slot antenna

Abstract: A quasioptical mixer using only planar structures such as coplanar-waveguide and slotline is presented. The mixer, which can be scaled for millimeter-wave applications and placed on a substrate lens, uses orthogonal modes in a folded-slot antenna to achieve intrinsic RF/LO isolation without BF filtering or subharmonic pumping. The folded-slot balanced mixer was fabricated on RT/Duriod and obtained a minimum isotropic conversion loss of 1.2 dB at 11.6 GHz. Numerical integration of full two-dimensional antenna patterns yielded an antenna directivity of 7 dB, corresponding to a single side-band (SSB) mixer conversion loss of 8.2 dB. The mixer demonstrated -18 dB RF/IF isolation and -30 dB LO/IF isolation. >