Showing papers on "Patch antenna published in 1973"

Microstrip antenna structures and arrays

Abstract: A microstrip antenna structure formed from a unitary conducting surface separated from a ground plane by a dielectric film where the r.f. radiator and feedlines form a generally planar arrangement of unitary integrally formed electrical conductors. The r.f. radiators are fed from an outside edge to selectively produce linearly and/or circularly polarized radiation at a selected resonant frequency(s). Necessary fixed phase shifting circuits are integrally formed by printed circuit techniques in the generally planar arrangement of electrical conductors for the circularly polarized radiators. A plurality of such antenna elements are also formed into a phased antenna array to achieve substantially ideal array gain thus producing an extremely high gain antenna with inexpensive printed circuit board construction techniques. Furthermore, appropriately controlled phase shifting networks may be integrally formed within the generally planar array of electrical conductors in combination with switchable diode elements to achieve any desired relative phase shifts between the array elements and thus to steer the array beam in a desired direction.

A theoretical and experimental study of the insulated loop antenna in a dissipative medium

Abstract: The performance of a bare antenna as a radiator in a dissipative medium can be significantly altered by placing a dielectric coating around the antenna. For certain antenna types and specific properties of the dissipative medium, the dielectric insulation has been shown to improve the performance of the antenna. In this paper the thin-wire circular-loop antenna centered in an insulating spherical cavity and immersed in an infinite homogeneous isotropic dissipative medium is analyzed. A Fourier series solution for the antenna current distribution is derived. The coefficients of the series are a combination of the coefficients for the loop in an infinite dielectric medium, which were determined previously by Wu [1962], and a second term, which is an infinite sum. The properties of the sum are examined, and expressions for the antenna input admittance, impedance, and electromagnetic field in the dissipative medium are obtained. Numerical results are presented for specific antenna sizes and dissipative media. For the special case of a loop with a uniform current distribution in an electrically small sphere the expression for the input impedance is shown to reduce to a solution previously given by Wait and Spies [1964]. The construction of an experimental model for the antenna is discussed, and antenna input impedances and current distributions measured with the model immersed in various salt-water solutions are compared with theoretical calculations.

A Potential Theory Method for Covered Microstrip (Short Papers)

Abstract: Matrix methods are used to analyze the properties of covered microstrip. The Green's function is calculated by a potential theory method assuming the TEM mode of propagation. Computed impedance values of covered microstrip agree closely with other experimental and theoretical data. The technique is a general one and can be used to treat multiple-layer and covered microstrip.

Log periodic pole mounted marker beacon antenna

Abstract: An ILS marker beacon antenna of the type wherein a pair of parallel conductors form a balanced transmission line and support a plurality of lateral radiators of graded lengths. An unbalanced RF transmission line extends through one of the conductors to the apex feed point of the antenna with one conductor of the unbalanced line connected to one of the pair of conductors and the other conductor of the unbalanced line connected to the other of the pair of conductors for flow of RF current from the feed point along the balanced transmission line to the radiating elements. An electrically small dipole monitor antenna mounted on the parallel conductors terminates the balanced transmission line by short circuit in a region near the back of the log periodic antenna to prevent back radiation and monitor antenna operation.

Reentry vehicle stripline slot antenna

Abstract: A reentry vehicle antenna which is comprised of a stripline slot antenna with the antenna element including a stripline circuit board with a radiating aperture fed by a conventional strip transmission line. A feedback circuit is provided to control the input impedance of the antenna while operating into an RF transparent window as the window depth varies due to erosion upon reentry.

Roof mounted vehicle antenna

Abstract: An antenna particularly suited for Citizens Band frequency use, and is particularly designed for mounting upon the roof of vehicles. The antenna is of a U-shaped configuration having a base portion and parallel leg portions. The leg portions are adjustable in length, and the antenna is supported in spaced relation to the vehicle roof to reduce standing wave reflected frequencies. A gamma assembly is attached to the base region of the antenna constituting a tuning capacitor, and the spacing of the leg portions causes a reflection and multiplication of radio frequencies, during transmission, causing a vertical directional orientation of the transmitted signals resulting in superior transmitting characteristics.

Slot antenna with flare

Abstract: A slot antenna with a flare having flare member having integrally formed therewith a first half section of antenna member and a second half section of antenna member having formed therein slots, in which the second half section of antenna member is mechanically assembled with the first half section of antenna member to provide a slot antenna member.

Radiation from a spherical antenna covered by an inhomogeneous over-dense plasma layer

Abstract: The state-space method is used to obtain an exact solution for radiation from a spherical antenna coated by a lossy and inhomogeneous layer of plasma. It is assumed that the plasma is isotropic and the density decreases sinusoidally with radial distance. Between the antenna and the coating a plasma sheath is also introduced. The results show that for appropriate dimensions of the antenna and the plasma layer, a considerable increase can be obtained in the radiation of the antenna, by lowering the antenna frequency below the maximum frequency of the plasma.

Calculation of the early time radiated electric field from a linear antenna with a finite source gap

Abstract: This communication investigates the early time radiated electric field from an infinite cylindrical antenna having a finite source region. The results presented here may be used to predict the radiated field from a finite antenna for times such that the wavefront from the source gap has not reached the end of the antenna.

Antenna assembly for a capacitance-responsive safety device

Abstract: An antenna assembly for a capacitance-responsive personnel safety device consists of an antenna formed by bending a ribbon of flat metal into a loop capable of defining a continuous capacitance field, the bending taking place across the width of the ribbon; a shield of the flat metal substantially coextensive with the antenna loop positioned in spaced relation with respect to the loop, the surface plane of the shield being perpendicular to the surface plane of the antenna ribbon; and a dielectric material such as an organic polymer embedding the antenna and shield and maintaining the spaced relation thereof.

Current distribution on an infinite tubular antenna immersed in a cold collisional magnetoplasma

Abstract: Based upon a boundary-value formulation, a new approximate expression is derived for the total axial current on an infinite antenna immersed in an unbounded, cold, collisional magnetoplasma with a dc magnetic field oriented parallel to the antenna. Numerical results are presented for the current distributions over plasma parameters corresponding to each of the eight regions of the Clemmow-Mullaly-Allis diagram and for different values of the collision frequency.

Practical feed network design for antenna arrays

Abstract: Computational procedures have recently been developed which accurately determine the excitation (including mutual coupling effects) at each element of a closely spaced array enabling it to perform in some desired manner. A procedure for designing a transmission-line feed network capable of realizing these required excitations is described. The result is a narrow-band feed system composed simply of a transmission line together with a small number of stubs. A comparison between theoretical and experimental results is given.

On the Transformation of a Definite Integral Occurring in Antenna and Transmission Line Theory

Abstract: In solving problems of multiconductor antenna transmission lines excited by an incident plane wave electromagnetic field, it is necessary to separate the antenna mode from the transmission line modes. This is accomplished by suitably transforming the definite integrals that occur in the theory. The purpose of this correspondence is to explain in a meticulous manner how this is achieved.

Transient Response of an Asymmetric Cylindrical Antenna

Abstract: The time-domain transient response of a thin dipole antenna is discussed in terms of element lengths and the surge impedances of the transmission line and element terminals. Theory and measurements show that, unlike symmetric configurations, asymmetry in the element lengths, together with appropriate mismatch of the transmission line, produces radiation proportional to the first time derivative of the signal voltage, and replica reception proportional to the incoming field.