Showing papers on "Patch antenna published in 1988"

Improved design of the Vivaldi antenna

Abstract: The Vivaldi antenna and its feeding transition is investigated. A tapered transition from microstrip to symmetric double sided slot line, fabricated on a low dielectric constant substrate, exhibits a very wide operating frequency range, with no need for a shorting hole. The parameters of the antenna which influence the constancy of beamwidth with frequency are discussed, and the ability to determine the required beamwidth by controlling the antenna length is shown.

Aperture-coupled patch antennas with wide-bandwidth and dual-polarization capabilities

Abstract: The authors discuss the design of a wideband, dual-proportion, C-band patch radiator with a 20% bandwidth for input voltage-standing-wave ratio >

Magnetic tuning of a microstrip antenna on a ferrite substrate

Abstract: The operating frequency of a microstrip antenna on a ferrite substrate can be tuned by varying the DC magnetic bias field applied to the ferrite. The letter reports experimental work where a 40% tuning range has been obtained, with usable patterns and return loss over this band.

Characteristics of the equilateral triangular patch antenna

Abstract: The results of a comprehensive analysis of this antenna based on the cavity model with a coaxial feed source are given. The theoretical formulas are given, and the characteristics obtained from them are presented, including radiation patterns, percentages of power radiated, total Q-factors, input impedances, and their variations with feed position. A number of disagreements with previously published results are noted. The theoretical and experimental results are compared. The results of the comparison indicate that the equilateral triangular patch can be designed to function as a triple frequency antenna. A method for correcting for the nonperfect magnetic wall is suggested. >

Two-port higher mode circular microstrip antennas

Abstract: For circular microstrip antennas, single-mode design techniques work well for the dominant mode (n=1, where n is the azimuthal dependence of the fields in the antenna), but this is not the case for zero-order (n=0) and higher order (n>1) modes, where a modal expansion is necessary. The design of higher order dominant mode circular microstrip antennas is addressed, with an example and measurements for the n=3 case. Measurements for the n=3 modes show reasonable agreement with theory in the forms of the impedance loci, but the frequency dependence is in error by the order of the bandwidth of the antenna. A design example is given for a roof-mounted circular patch for vehicular communications. The example indicates that an n=3 dominant mode patch can be used as a two-port antenna for diversity applications or with a 90 degrees phase shifter and adder as a single-port antenna for omnidirectional coverage with (essentially) circular polarization. >

Simple model for the input impedance of coax-fed rectangular microstrip patch antenna for CAD

Abstract: We present a simple model for the input impedance of a rectangular microstrip patch antenna. This model is well suited for computer aided design (CAD). It is based on classical methods: (a) the cavity model determining the frequency and the input resistance at resonance, (b) the dynamic permittivity of a rectangular microstrip patch antenna (to take into account the influence of the fringing field at the edges of the rectangular patch antenna) and (c) the resonant parallel RLC circuit with an inductive reactance. This model is valid for electrically thick substrates. The theoretical results are in good agreement with experimental data.

Active radiating element using FET source integrated with microstrip patch antenna

Abstract: An FET source has been integrated with a microstrip patch antenna to form an active radiating module. The patch antenna serves both as a radiating element and a resonator in the feedback loop for the FET oscillator. Power output of 17mW was achieved at 5.7 GHz.

Antenna and its electronic circuit combination

Abstract: An antenna and its electronic circuit combination is presented to comprise a ground conductor plane 30, a radiating conductor plane 40 disposed in parallel spaced relation to the ground plane 30 and shorted at its one end to the ground plane 30. A ground plane 30 is preferably formed on a printed board 10 which is disposed in parallel relation to the radiating plane 40 to define therebetween an open air space. Mounted on the printed board 10 and received within the open air space are electronic components which form a receiving or transmitting electronic circuit 60 associated with the antenna structure and electrically coupled by means of a feed element 20 to a feed point 44 on the radiating plane 40. Consequently, a number of electronic components forming the electronic circuit for the antenna can well be incorporated within the antenna structure by better utilization of the open air space formed between the radiating and ground planes, giving a space saving compact arrangement to the antenna and its electronic combination suitable for installation in a limited space.

Microwave circuit module, such as an antenna, and method of making same

Abstract: A microwave circuit module, more particularly an antenna, comprised of a polyethylene foam substrate having a loss tangent less 0.001 and a dielectric constant less than 1.3, a predetermined pattern of one or more elements, such as an array of n×m radiator elements, formed of electrically conductive material, deposited on a first surface of the substrate, and an electrically conductive ground plane secured to the opposite surface of the substrate. In the antenna embodiment, a feed network formed of electrically conductive material is deposited on said said first surface of the substrate for electrically interconnecting the radiator elements in the array; and I/O means are coupled to the feed network for supplying a signal to be transmitted by the antenna or for receiving a signal received by that antenna.

Aperture coupled circular polarization antenna

Abstract: A generally planar antenna for generating circularly polarized electromagnetic signals, particularly useful at microwave frequencies. Each antenna element comprises a single excitation aperture (7) cut in a planar conductive ground plane (9). Spaced apart from the ground plane (9) by means of a dielectric layer (11) and covering the excitation aperture (7) is a planar conductive radiating patch (5) having slightly different dimensions along each of two orthogonal axes. The radiating patch (5) may have the shape of a near square or an ellipse. Exciting the aperture (7) with linearly polarized electromagnetic energy causes the radiating patch (5) to generate a circularly polarized electromagnetic signal consisting of two orthogonal components that have substantially the same amplitude and are 90° offset in phase from each other. Several antenna elements can be combined to form a large aperture array. Energy may be applied to the excitation aperture (7) by means of a waveguide (3) feed, microstrip line (15), or stripline (15).

An improved formula for the resonant frequencies of the triangular microstrip patch antenna

Abstract: An improved version of a formula due to J.S. Dahele and K.F. Lee (ibid., vol.AP-35, p.100-101, Jan. 1987) is presented for predicting the resonant frequency of a triangular microstrip patch antenna. Using a different effective length and the actual substrate permittivity, the technique previously used for the case of a circular disk is modified to produce greater accuracy than previously reported in the literature. This method consistently predicts resonant frequencies more accurately through the first five resonances. >

A wider band microstrip antenna for circular polarization

Abstract: Circular polarization is achieved by separating two degenerate orthogonal modes in an annular ring patch antenna, by using an ear at the outer periphery. The analysis of such a structure is performed by using the generalized transmission line model. It is found theoretically that this structure can be used to generate circular polarization over a wider frequency range than other structures. An annular ring is designed and its performance is evaluated. Good agreement between the theory and the experiment is obtained. It is also found that the axial ratio bandwidth is higher for the TM/sub 12/ mode than the TM/sub 32/ mode of operation in an annular ring antenna. >

New determination of resonant frequency of circular disc microstrip antenna: application to thick substrate

Abstract: An analytical expression is presented for the resonant frequency of a circular disc microstrip antenna with a thick dielectric substrate. It shows explicitly the dependence of the resonant frequency on the characteristic parameters of a patch antenna. The theoretical results are in good agreement with experimental data.

Planar TV receiving antenna with broad band

Abstract: A TV receiving antenna with broad band and capable of connecting with a coaxial cable comprising a sheet of electrically non-conductive synthetic plastic material; a pair of antenna elements of metallic foil in the shape of substantially a triangle or a combination of a triangle and a rectangle being superimposed on one side of said sheet, a pair of frequency compensating members of snake-shaped strip line of metallic foil connected to said antenna elements respectively being superimposed on the one side of said sheet; a pair of antenna elements of metallic foil in the shape of a trapezoid or a combination of a trapezoid and a rectangle being superimposed on the opposite side of said sheet; a pair of frequency compensating members of snake-shaped strip line of metallic foil connected to said antenna elements respectively being superimposed on the opposite side of said sheet; and impedance transformers of microstrip lines of metallic foil on each side of said sheet also superimposed for matching the antenna elements and the coaxial cable. Each antenna element can have a plurality of parallel slots for the selection of polarization. The antenna can receive TV signals both in UHF and in VHF bands and eliminate ghosts. It is suitable for mass production by etching the patterns on a laminated sheet for printed circuits.

Helical type antenna and manufacturing method thereof

Abstract: A helical type of antenna has at least one radiating cord, helically wound in a rotational shape. The antenna has a circuit for the supply of the radiating cords formed by a strip line type of transmission line which fulfills both the supply distribution function and the function of matching the radiating cords of the antenna.

Coplanar patch antenna

Abstract: A coplanar patch antenna is formed, e.g as a printed circuit, on a dielectric support (1) by a metal patch (2) spaced from a coplanar ground plane (3) by a peripheral slot (4), and in the improvement is series fed by means of a slot line (5). The slot (4) can be made resonant by having a periphery of one wavelength or an odd multiple thereof, and a second slot line (7) can be fed into the slot (4) at a distance of one or an odd multiple of a quarter wavelength from the slot line (5) to provide an independent feed. The arrangement presents a feedpoint impedance of about 50 ohms at the ports (6,8) instead of about 400 ohms in prior arrangements. Balancing loads or 180 degree hybrid feeds to other quadrature ports (11,12) can be used to correct beam asymmetry due to the slot line feeders (5 and 7).

Plural layer co-planar waveguide coupling system for feeding a patch radiator array

Abstract: An antenna system for an array antenna includes an array of radiators formed as patch antenna elements on a dielectric substrate, there being a shielding metallic sheet on a side of the substrate opposite the radiators. A further dielectric substrate and a bottom metallic sheet are disposed on a side of the shielding sheet opposite the radiators. An antenna feed system is disposed in the further sheet. Coupling devices such as orthogonal slots, in one embodiment, or a microwave crossover in a second embodiment, couple electromagnetic power from the feed system to the radiators through the shielding sheet. In the case of the coupling slots, the feed system provides phase quadrature signals for development of circularly polarized radiation. The crossover provides only a linearly polarized wave, and is formed of two coplanar waveguides, one in the shielding sheet and one in the bottom sheet. Each of the coplanar waveguides includes a pair of coupling pads, the pads of one waveguide being in registration with the pads of the other waveguide.

Magnetised microstrip antenna with pattern control

Abstract: Measured results are given for a novel microstrip antenna with in-built pattern control capabilities. The antenna element consists of a metal patch etched onto alumina substrate with a thick ferrite overlay, which is then magnetised by a permanent magnet, H-plane patterns showing a 30° scan are given and a simple analysis of this new device explains the principal mechanisms involved.

Excitation of propagating magnetization waves by microstrip antennas

Abstract: We discuss the self-consistent theory of excitation of dipole-exchange magnetization waves by microstrip antennas in a metal-dielectric-ferrite-dielectric-metal stratified structure, magnetized under an arbitrary angle to the surface. Spin-wave Green's functions are derived, describing the response of the spin-system to a spatially inhomogeneous varying magnetic field. The radiative resistance of microstrip antenna is calculated. In this case the distribution of surface current density in the antenna is found on the basis of the analytic solution of a singular integral equation. The nature of the effect of metallic screens and redistributed surface current densities in the antenna on the frequency dependence of the resistive radiation is investigated. Approximate relations are obtained, convenient for practical calculations of radiative resistance of microstrip antennas both in a free and in a screened ferromagnetic film. The theoretical calculations are verified by data of experiments carried out on monocrystalline films of iron-yttrium garnet.

Microstrip patch antenna with omni-directional radiation pattern

Abstract: A microstrap patch antenna with a substantially omni-directional radiation pattern includes an upper hemisphere microstrip patch radiator working against a ground plane and a lower hemisphere microstrip patch radiator working against a ground plane, the ground planes being oriented in close proximity and spaced apart from each other. One of the radiators is excited in left hand circular polarization and the other in right hand circular polarization such that their fields add constructively across their ground planes to achieve an omni-directional radiation pattern.

Antenna apparatus for a vehicle

Abstract: An antenna element conductor is formed on a transparent insulating film. An adhesive is applied to the rear surface of the film. A connector is provided to a feeder terminal. A print antenna comprising the film and the antenna conductor can be attached to a glass surface, and a position of the antenna on the window glass can be desirably selected so as to obtain good antenna characteristics.

Spatial power combining using active microstrip patch antennas

Abstract: Active antenna elements have been fabricated using Gunn diodes and microstrip patch antennas. The power outputs from two of these elements have been successfully combined in space. Frequency coherency was achieved by injection locking using either the spatial locking technique or the mutual coupling locking technique.

Millimeter wave microstrip to coaxial line side-launch transition

Abstract: A side-launch transition for efficiently joining a coaxial transmission line or coaxial connector to a microstrip transmission line for operation at millimeter wave frequencies. The microstrip transmission line comprises a conductive microstrip pattern on one side of a dielectric substrate and a ground plane on the other. The conductive microstrip pattern includes a rectangular terminal pad area of a predetermined length designed to be approximately equal to the wavelength of the signal being transmitted. This pad area is integrally joined to the microstrip line. A circular iris or aperture, is formed through the ground plane and is in a centered alignment with the terminal pad on the opposite side of the substrate. A small hole extends through the center of the iris and penetrates the substrate as well as the conductive pad area. The outer shield conductor of the coaxial transmission line or the coaxial connector and the dielectric material insulating it from its center conductor are stripped back to expose a predetermined length of center conductor which is then fitted through the small hole from the ground plane side of the substrate and soldered to the conductive pad. The outer shield is likewise soldered or otherwise conductively bonded to the ground plane in the vicinity of the iris aperture.

Electronically tunable antenna

Abstract: A resonant helical antenna capable of being tuned electronically over a broad range of frequencies. The helical turns of the radiating portion of the antenna are formed of tubular material which may be in the form of a single length of tubing or may comprise a number of parallel coaxial cables with their outer conductors in electrical contact. The antenna is tuned by a series of oppositely poled pairs of diodes that are connected at spaced points to the radiating coils of the antenna. When the diodes are biased to be conducive, a section of the radiating helix is short-circuited. Bias voltages to control the diodes are provided by leads inside the radiating turns of the helix. Each lead for a pair of diodes emerges at a point electrically balanced between the two spaced points that are connected to the associated diodes. No r-f potential exists between the outer and inner conductor of the radiating runs at the point where the bias lead emerges, so no r-f current flows in the bias lead wires. The antenna may include spaced cpacitance elements and may be in the form of a monopole helical antenna or it may be in the form of a dipole antenna with two oppositely-disposed arms.

Helix-type antenna and its manufacturing process

Abstract: The antenna comprises at least one radiating wire (11, 12, 13, 14) wound into a helix following a body of revolution (1). The antenna comprises a supply circuit (2) for the radiating wire(s) which consists of a transmission line of the strip line type (20), which ensures both the function of distribution of supply and of matching of the radiating wires of the antenna. Application to the construction of circularly polarised radiating antennas for satellite telecommunications, radiolocation.

Multiport network model and transmission characteristics of two-port rectangular microstrip patch antennas

Abstract: A multiport network model for two-port rectangular microstrip patch antennas is introduced. This model is capable of accounting for the feedline-patch junction reactances as well as for the mutual coupling among the edges of the patch, and is used to evaluate two-port transmission characteristics of rectangular patches. The proposed model has been applied to the analysis of rectangular patches used as elements of series-fed microstrip arrays. Results presented show that it is possible to match a two-port patch at the input port and, at the same time, to achieve a specified transmission coefficient to the other port to taper the amplitude distribution of the array appropriately. These experimental results verify the validity of the proposed model and the method of analysis used. >

A linearly-polarized radial line slot antenna

Abstract: The authors present the design of a linearly polarized RLSA (radial line slot antenna). A key feature consists of the slot arrangement that realizes the linear polarization of the rotationally symmetric travelling wave excitation. The design is verified by experiments. Fresnel patterns indicate the reasonable XPD of more than 17 dB. To suppress the reflection from slots, beam tilting techniques should be used in the practical design of the linearly polarized RLSA. >

Superimposed dichroic microstrip antenna arrays

Abstract: The dichroic microstrip antenna concept is reported which enables an antenna aperture to function at two widely separated frequencies fH and fL. The innovation centres on the utilisation of printed frequency selective mesh conductors as microstrip patch antennas at fL, which in turn become transparent to near-field radiation at fH, from another microstrip array in close proximity. An approximate analysis shows that the mesh perimeter scattering has a dominant effect on the degree of invisibility achievable, and for simple configurations the NEC computer program models the behaviour which also includes a leaky wave action. Radiation pattern measurements on several microwave and millimetre dual band arrays using low permittivity (er = 1.05) substrates illustrating the concept are presented and a further development concerning an array that also functions as an electromagnetic window. The measurements show the effect of mesh strip width, patch impedance levels, band separation and feeder radiation, but the small dissipative loss in the mesh is difficult to precisely ascertain. Despite the complexity of effects produced by the mesh its transparency is good and radiation pattern perturbations, reduced by the array factor, are typically 1 to 2 dB. However, the use of higher permittivity substrates may lead to some bandwidth restrictions and some increased mesh dissipation loss. Finally, numerous possible applications for the innovative dual band structures presented, are noted.

Modelling of microstrip antenna with dielectric protective layer for lossy medium

Abstract: Microstrip antennas are used for biomedical applications; however, their modelling is not easy. We present an approach to simulating a microstrip antenna with a dielectric protective layer radiating into a lossy medium. Using a classical spectral domain approach (SDA) model, calculations of the resonant frequency have been performed, and compared with experimental measurements for simple structures of microstrip antenna with different geometric parameters.

Microwave antenna structure with intergral radome and rear cover

Abstract: A suspended line feed type planar antenna is arranged with a number of antenna elements formed on a film-shaped substrate, and the film-shaped substrate is sandwiched between a plastic radome and a plastic rear cover, a conductive surface is plated on the rear surface of the plastic radome at its portion except the portions opposing the antenna elements and/or a conductive surface is plated on the whole front surface of the rear cover. The conductive surfaces and the antenna elements constitute resonance type printed path radiators, whereby the planar antenna of the invention can be simplified in construction and reduced in cost, thickness and weight, and the planar antenna of the invention can be increased in productivity and reliability.