Showing papers on "Patch antenna published in 1977"

Resonant frequency of a circular disc, printed-circuit antenna

Abstract: The resonant frequency is obtained in analytical form for a planar, circular disc antenna which is etched on a printed-circuit board so that the low-profile antenna is separated from the ground plane only by a thin layer of dielectric material. The formula is found to have an error of less than 2.5 percent when compared with experimental data.

Radio frequency ring-shaped slot antenna

Abstract: An array antenna is disclosed wherein each one of the antenna elements includes at least two concentric slots formed in a conductive sheet. The conductive sheet is disposed on a dielectric support and a ground plane is found on the opposite surface of such support. The inner one of the slots enables the outer slot to radiate radio frequency energy having a wavelength greater than the circumference of such outer slot. When such antenna includes an additional concentric slot the antenna is adapted to operate over a pair of frequencies separated by greater than twenty percent while enabling the array antenna to have satisfactory grating lobe characteristics.

Equivalent Series Inductivity of a Narrow Transverse Slit in Microstrip

Abstract: The series inductivity introduced by a narrow transverse slit in a microstrip transmission line has been evaluated theoretically, and a simple formula for this inductivity is presented Experimental results for slits of different depth obtained with the resonant ring method compare well with theory Applications of such a slit include the fine tuning of the electrical length of stubs and the compensation of excess capacitances at discontinuities

Flush-mounted piggyback microstrip antenna

Abstract: A dual radiating system where one radiating element is placed atop the ot in a piggyback fashion. The elements can be a pair of microstrip or dielectric-loaded parallel plate radiators, or it can be a combination of the two. Separate coaxial lines feed each of the radiators, and there is a minimum of coupling from one antenna to another. The antenna can be used alone or more effectively in a linear or planar conformal array.

Windowed dual ground plane microstrip antennas

Abstract: Microstrip antenna systems having two ground planes spaced apart by a dietric substrate and radiating elements coplanar with one of the two ground planes, or sandwiched within the dielectric substrate separating the two ground planes adjacent a window in one of the ground planes. The two ground planes are shorted together in most instances, and the dual ground plane system provides a reduction in the leakage losses of transmission lines feeding and/or interconnecting the microstrip antenna radiating elements. The dual ground plane system also provides a reduction in coupling between arrayed radiation elements as well as an increase in bandwidth, in some instances.

Microstrip antennas and arrays. Part 1: Fundamental action and limitations

Abstract: Consideration of the radiation mechanism of an open-circuit microstrip termination indicates that the terminal-plane region is the dominant radiating aperture. On this basis, the radiation patterns of several types of microstrip radiating elements in rectangular and cylindrical geometry are calculated and substantiated by experiment. In general, the patterns exhibit the characteristics of slot radiators, thus endorsing the action of an end-radiating aperture; the radiation admittance of the latter is obtained by novel measurements of the standing waves in a truncated microstrip line but, when the substrate extends beyond the radiating aperture, substrate surface waves are generated. An analysis of the substrate waves indicates that the side-lobe level of an array of microstrip radiating elements could be limited to around -20 dB, and severe unwanted coupling effects between microstrip circuits are also noted. The use of substrate troughs to reduce the surface-wave generation is discussed, and a strip width-modulation technique proposed to control the array aperture distribution and simplify the feeding configuration. The implications of these present findings on the potential performance of microstrip antenna arrays is discussed and design recommendations made; the latter are investigated in a companion paper.

Loaded microstrip antenna with integral transformer

Abstract: A microstrip antenna design according to which the impedance matching transformer is contained in the area usually occupied entirely by the etched metal radiator.

Triband vehicle antenna

Abstract: An antenna for simultaneous connection to a citizen's band transceiver, an AM receiver and a FM receiver, particularly suitable for use on a vehicle such as an automobile. The antenna proper is a center-loaded upstanding rod which, in the preferred form, telescopes downwardly to a retracted position where it does not protrude above the ground plane. The antenna proper is connected to a T-connected open stub transmission line and to a FM resonant relatively high impedance signal-carrying transmission line. The former has inductive reactance in the FM band which offsets the capacitive reactance of the relatively short effective length of the antenna proper in the FM frequencies. The signal-carrying transmission line is substantially half wave in length in the FM band so as to reflect impedance at its far end substantially equal to the impedance present at the T-connection. The signal-carrying transmission line is also of length that provides resonant action transforming the relatively low impedance at the T-connection or base of the antenna in the CB band to a higher impedance, such as 50 ohms, at the end of that transmission line. Finally, the signal-carrying transmission line, because of its relatively high characteristic impedance, has very low capacitance and therefore does not tend to load the AM radio. The end of the signal-carrying transmission line is connected to the input terminal of splitter containing resonant circuits which are in turn connected to two transmission lines, one leading to the CB transceiver and the other leading to the AM/FM radio.

Missile base mounted microstrip antennas

Abstract: Proof of the feasibility of aft mounting low-profile antennas on reentry vehicles is presented. This is an application of state of the art antenna hardware. Aft mounting presents the best reentry environment to antenna hardware, and its practicality has been demonstrated. Microstrip antenna principles can be used to produce very rugged antennas. Their low profile reduces many interface, mechanical, and survival problems. The pattern coverage for these vehicles must be toward the fore direction. This type of pattern requires an interaction between the vehicle and the antenna when the antenna is effectively shadowed from that direction. This paper describes the results obtained by actual experimental hardware. Contoured elements were used, as were foreshortened elements. These elements demonstrated ability to be fit around other aft equipment. The versatility of these elements were further demonstrated by tailoring them for two different types of coverage to accommodate different vehicle operational requirements.

Transmission line theory of antenna impedance in a magnetoplasma

Abstract: Transmission line theory for the impedances of wire antennas immersed in a cold magnetoplasma is proposed The theory is applicable to antennas which are not necessarily small in terms of a wavelength measured along the antenna wire The transmission line theory for the impedance of a very thin cylindrical dipole antenna leads to the Balmain quasi-static theory when the antenna length reduces to zero New impedance resonances which would be observed for antennas of finite length in a magnetoplasma in the frequency region below and near the electron cyclotron frequency are predicted by the present theory

Microstrip antennas and arrays. Part 2: New array-design technique

Abstract: Open-circuit terminations on half-wavelength stubs form the radiating elements in a new design technique for linear microstrip microwave arrays. Measured results, on computer-designed resonant and wideband travelling-wave arrays with broadisde beams, demonstrate the technique; the effects of corporate feeds and radomes are also considered. The computer design of medium gain arrays, with H-plane sidelobe levels below about -21 dB, demands characterisation of the microstrip T-junction with an accuracy that is currently unavailabe, and the dimensional precision has to be obtained by experimental means. It is concluded, to date, that the known extraneous sources of radiation do not inhibit the control of H-plane sidelobes to a level of at least -25 dB and the new design technique makes microstrip arrays highly competitive with their conventional waveguide counterparts.

High efficiency microstrip antenna structure

Abstract: A microstrip antenna wherein a cavity or channel is formed in the ground plane conductor to reduce radiation losses and cross-coupling between elements. A shielded embodiment is also disclosed.

Broadband microstrip disc antenna

Abstract: A broadband antenna including a conductive disc parallel to and spaced from a ground plane with dielectric material therebetween, the disc including a first sector of approximately 270° having a first diameter and the remaining sector having a second diameter different from the first so that the equivalent resonant structure of the antenna is essentially detuned to broaden the bandwidth thereof, and a cylindrical array of such antennas for providing a desired radiation pattern, generally omnidirectional.

Three band monopole antenna

Abstract: A three band monopole antenna with such length as to be of greater electrical length than a quarter wavelength of the two highest frequency bands and shorter than a quarter wavelength of the lowest frequency band. The antenna system includes a matching network at its base matching the antenna on three frequency bands related by, substantially, the progression 1, 2, 4, and with the matching network including a shunt inductor and an inductor and capacitor in series with the signal feedpoint.

The horizontal-wire antenna over a dissipative half-space: Generalized formula and measurements

Abstract: It is shown and verified by experiment that a horizontal resonant or traveling wave antenna placed in air close to a dense halfspace with the properties of lake or sea water or earth behaves like a terminated lossy transmission line. The terminal impedance is related to the radiation of the antenna into the air and the complex wavenumber and characteristic impedance are those of an infinitely long line. The complex wavenumber takes account of both dissipation in and radiation into the dense half-space.

Technique for calculating the radiation and scattering characteristics of antennas mounted on a finite ground plane

Abstract: The problem of an antenna mounted on a conducting body is formulated by using a modification of the isolated thin-wire kernel with the numerical Green's function for the body. This formulation is then employed for the investigation of the problem of a monopole antenna over a finite ground plane. The numerical Green's function for the plate is obtained by applying the finite-difference technique, which has previously been successfully applied to the thin-wire junction problem. A user-oriented Fortran program is developed, and extensive numerical results are reported.

Broadband hybrid monopole antenna

Abstract: A new type of radiating structure with rugged high frequency design comprng essentially a single hybrid monopole which utilizes capacitive coupling from a open-ended transmission line to accomplish its broadband characteristics. The monopole is a metal conductor concentric with the transmission line and is separated from a ground plane by an adjustable gap that may be effectively used for fine tuning the antenna. By utilizing helical springs as the conductors this hybrid monopole antenna has self-erecting or pop-up design capability.

Antenna coupling network with element pattern shift

Abstract: In any array antenna system having a coupling network interconnecting a plurality of element groups, the coupling network is provided with phase adjustments to shift the angular location of the effective element radiation pattern. An effective technique for this phase adjustment in a microstrip coupling network makes use of a field altering structure positioned adjacent the microstrip.

Rodholder mounted antenna

Abstract: A portable transceiver antenna is provided with a base suitable for retention by a fishing rodholder or for hand held use and is pretuned to facilitate its use without a ground plane. The antenna includes an electrically conductive rod which may be covered by a dielectric and segmented, and would then include couplings fabricated from ferrules closely fitted over nipples to produce reliable electrical contact through the coupling. The antenna may be used with citizens band, very high frequency - frequency modulated, and similar applications.

Antenna/like impedance matcher

Abstract: A matching coupler in an antenna system to power transfer in matching characteristic impedance of an antenna and a transmission line using a ganged variable capacitance with a resonate coil and another variable capacitance in series with a transmission line and an antenna.

Circular microstrip antennas

Abstract: The circular microstrip antenna is analyzed by developing the field equations within the antenna in terms of Bessel functions. When the order of the Bessel functions is 1, the antenna radiates normal to the surface on which the antenna is mounted. Equations are developed for calculation of radiation patterns, impedance, bandwidth and efficiency when the antenna is operating in this mode. Curves are provided to assist in the design of a circular microstrip antenna.

Truncated dielectric-coated conducting sphere excited in the TM-symmetric mode as an antenna

Abstract: Expressions for the radiated field and gain of the truncated dielectric-coated conducting sphere have been derived. The calculated radiation patterns and gains of several structures of varying dimensions have been verified experimentally in the X-band.

Waveguide antenna switches using p-i-n diodes

Abstract: A waveguide antenna switch at L-band, using mass-produced p-i-n diodes located in the aperture, is described. Low forward loss and good isolation over a bandwidth of about 30% are achieved.

On the Measurement of Microstrip Discontinuity Scattering Matrices by a Resonance Technique

Abstract: A new simple solution to the problem of experimentally characterizing the behaviour of symmetrical microstrip discontinuities is presented. To perform the measurement, a resonant cavity consisting of a couple of identical microstrip sections connected by the discontinuity to be tested is built, together with a reference circuit made of a length of uniform transmission line. The resonant frequencies of the test and reference device are then measured as accurately as possible, and the scattering parameters of the discontinuity are related to these frequencies by means of very simple, explicit formulae.