Showing papers on "Patch antenna published in 1980"

Improved bandwidth of microstrip antennas using parasitic elements

Abstract: A method is described of doubling the bandwidth of rectangular microstrip patch antennas by locating capacitively excited λ m /4 short circuit parasitic elements at their radiating edges. The antenna characteristics are explained in terms of an antiphase mode of a pair of coupled resonators, and it is shown that the bandwidth improvement is independent of the coupling capacitance. Experimental results are presented for both linearly and circularly polarised antennas which support the theoretical predictions.

Design Considerations in Microstrip Antenna Fabrication

Abstract: Deviations in effective electrical dimensions caused by slight variations in finished microstrip antenna length, variations in the relative permittivity of the substrate material or nonuniformity in the substrate thickness lead to discrepancies between the designed and actual resonant frequencies. This sort of discrepancy is especially significant because of the narrow bandwidth of such antennas. It is found that for low dielectric substrate microstrip antennas, the critical parameter affecting the change in resonant frequency is the error in antenna length while for high permittivity substrates, the tolerance in dielectric constant is the critical parameter.

Simple rock compensating device for antenna mounted on traveling object

Abstract: PURPOSE:To realize a light weight for the whole of a rock compensating device and facilitate easy control of the natural period of the device, by joining a unified structure of an antenna and a radio machine to a supporter of a traveling object via a rotary junction part and then giving control to the space between the rotational center of the rotary junction part and the centroid of the unified structure. CONSTITUTION:An antenna 3c and a radio machine 13 are fixed relatively in terms of position via an antenna post 4c to form an equivalent pendulum through a unified structure of the antenna and radio machine. A hanging frame 14 has a slender slit 16 at the area of joint to a rotary junction part 15 and in the lengthwise direction of the frame 14. Then a space between the centroid of the unified structure and rotary shafts 7 and 8 each is controlled. After this, a screw 19 is driven. In such way, the rocking of the antenna 3c can be reduced compared with that of a traveling object.

Frequency-agile, polarization diverse microstrip antennas and frequency scanned arrays

Abstract: An inexpensive, flush mounted microstrip antenna which is frequency agile d has polarization diversity. The frequency and polarization of the antenna can be selected by selecting the location of shorting posts in the antenna. The use of switching diodes in place of shorting posts provides the means of electronically switching the frequency and polarization characteristics of the antenna. Frequency-agility provides frequency scannable microstrip antenna arrays which also have polarization diversity. Frequency-agility, polarization diversity and frequency scannable arrays are controllable by digital means such as a computer.

Microstrip Transmission Line with Finite-Width Dielectric

Abstract: The results of a numerical solution for open microstrip transmission line with finite-width dielectric are presented for a quasi-TEM computational model. The related solution is based on moment methods using equivalent source models for the free and bound charges existing on boundary surfaces. Characteristic impedance and velocity of propagation are presented in graphical form for estimating the effects of dieletric truncation on microstrip circuits and for related circuit design.

Circular ring microstrip antenna elements

Abstract: The frequency characteristics of circular ring microstrip antennas were obtained as a function of relative aperture radius. In all cases the resonant frequency was normalized to that of an ideal disk microstrip antenna with the same radius, and assumed magne tic wall boundary conditions. Since, at this time, an exact value for the complex wall admittance is not known, an equivalent admittance was derived for each of several commonly used models. This admittance was then used as the boundary condition for the computation of the resonant frequency as a function of relative aperture radius. Results of these calculations are shown; also shown is the comparison with experiment.

Selectable-mode microstrip antenna and selectable-mode microstrip antenna arrays

Abstract: An inexpensive, flush mounted selectable mode microstrip antenna which is equency-agile and has polarization diversity. The mode, frequency and polarization of the antenna can be selected by selecting the location of shorting posts in the antenna. The use of switching diodes in place of shorting posts provides the means of electronically switching the mode, frequency and polarization characteristics of the antenna. The selectable mode microstrip antenna arrays are also provided. The selection of mode, frequency and polarization can be selected and controlled by digital means such as a computer.

New wideband microstrip antenna using log-periodic technique

Abstract: A novel wideband microstrip antenna using a series-fed linear array of patch resonators in a log-periodic arrangement is described. A 9-element example gives good input v.s.w.r. and radiation control over a 30% bandwidth with better than 70% efficiency. The new array configuration gives wider bandwidth than single-layer or stacked microstrip patches combined with better efficiency than patches on lossy substrates or microstrip spirals.

A Broad-Band Element for Microstrip Bias or Tuning Circuits (Short Papers)

Abstract: A microstrip radial transmission line circuit element namely a 180/spl deg/ circular stub or "half-moon" structure, having a reflection coefficient of unity magnitude and phase which varies slowly with frequency is presented. Theoretical reflection coefficient data are shown to agree well with experimental microstrip (epsilon/sub r/=2.35, h =250 mu m) data in X band. Applications of the half-moon microstrip element in the design of broad-band bias or tuning networks are discussed.

Radiation characteristics of a circular microstrip antenna

Abstract: Radiation patterns of a circular microstrip antenna have been calculated with Green’s functions for a two‐layer medium and compared with previous results which are valid for thin slabs and small dielectric constants A mode expansion technique is then used to find fields and resonant frequencies The theoretical results for the input impedances are found and are in good agreement with experimental data

Around-a-mast quadrifilar microstrip antenna

Abstract: A down link UHF antenna is designed which includes four equispaced arms ml plated at an angle on a fiberglass cylinder A coaxial connector is connected to each of the four arms with the metal plated inner surface as the common ground

Calculation of Quasi-Static Characteristics of Microstrip on Anisotropic Substrate Using Mapping Method

Abstract: In this paper a mapping transforms a original microstrip line on anisotropic substrate into another on isotropic dielectric. This method is applied to compute the quasi-static impedance of single microstrip on an anisotropic sapphire substrate.

Hemispherical coverage microstrip antenna

Abstract: A single antenna having hemispherical coverage with circular polarization very low axial ratio is disclosed. Its pancake structure comprises two stacked microstrip antennas, one atop the other, each fed phase shifted in relation to the other. Used as transmitter or receiver antenna, it replaces conventional hemispherical types with an extremely compact and relatively inexpensive device.

Integrated spiral antenna-detector device

Abstract: An integrated antenna-detector device sensitive over a broadband of frequencies with an extended high frequency limit comprising a pair of antenna elements each having first and second ends, the first ends of the elements being positioned proximate to each other while the second ends are displaced from the first ends, a detector unit positioned and connected between the first ends of the antenna elements, and signal output means connected with the antenna elements at a location displaced from their first ends The signal output means delivers detected output signals from the antenna elements, and also delivers a biasing signal to the detecting unit The device may take a number of forms including that of a dipole antenna having a linear or conical configuration, and in which a plurality of such dipole elements are arranged to form a log-periodic antenna, and where the pair of antenna elements are arranged to provide a pair of interwound spiral conductive windings to form a spiral antenna

The equivalence of the electric and magnetic surface current approaches in microstrip antenna studies

Abstract: It is shown that the fields produced by the electric surface currents on the conducting patch of a microstrip antenna are equivalent to those produced by a magnetic surface current sheet bounding the patch in the substrate only when dyadic Green's functions for the two-layer stratified medium are used.

A cavity-backed resonant slot array--Theory and measurement

Abstract: An antenna is described which consists of a broadside array of half-wavelength slots backed by a single cavity containing a filter that allows resonance with a mode suitable for the excitation of the array. A formula for the input resistance at resonance is derived using a mathematical model which is valid only if the cavity is highly underdamped and if the individual slot spacings exceed half a free-space wavelength. By proper choice of dimensions it is shown that the antenna can be matched to an external power source. Measurements were made on two arrays at 10 GHz, and results are consistent with calculations. The observed radiation patterns agree with expected field distributions provided there are no metallic projections on the plane of the array.

H-Plane Coupling between Rectangular Microstrip Antennas,

Abstract: A new model that theoretically characterises mutual coupling effects between two rectangular microstrip antennas is presented. Numerical S-parameter results exhibiting mutual coupling effects are reported.

Antenna for direct reception from satellites

Abstract: 1. A receiving antenna for direct satellite reception, having a pivoted antenna construction with an antenna reflector (1), in particular of parabolic shape, provided with a reference marking (2) extending in the direction of the electric axis (A1) of the antenna and defined by pre-adjustment in accordance with the radiation pattern of the antenna, characterised by the following features : a) the reference marking (2) consists of two mutually connected components (3, 4), of which one component (3) is mounted on the antenna construction so as to be pivotable about a first axis (5) and the second component (4) is mounted on the first component (3) so as to be pivotable about an axis (12) which is at right angles to the first axis ; b) the two components consist of planar adjacent plates (3, 4) having respective strips (8, 11) bent upwardly at right angles on mutually adjacent and parallel longitudinal sides ; c) the strip (11) of the second plate (4) forms the reference marking (2) and simultaneously serves to accommodate an adjusting screw (10) which allows the second plate (4) to be vertically pivoted ; and d) a device for adjusting the antenna in elevation and azimuth is provided, equipped with a contact edge (36) or contact surface which can be coupled to the reference marking (2).

Rectangular beam shaping antenna employing microstrip radiators

Abstract: To provide improved performance in a microwave antenna, particularly for use in a Doppler navigation system, rectangular arrays obtained from truncated slanted arrays are used to obtain beam shapes which exhibit a high degree of independence from over-water shifts.

Multi-mode Luneberg lens antenna

Abstract: An antenna system having a multiple of antenna feeds to drive a microwave ns, composed primarily of a Luneberg lens and a metallic ground plane upon which are mounted three antenna feeds and a shorted stub (or four bent-stub coaxial feeds). The antenna system uses a common aperture to provide antenna performance for the three separate feeds, conserving space that would normally be required for three separate high gain antennas.

E-plane coupling between two rectangular microstrip antennas

Abstract: A model which theoretically characterises end coupling (E-plane coupling) between two rectangular microstrip antennas is discussed. Computer generated S-parameter results for this particular type of mutual coupling are presented.

Microstrip rectangular resonators on ferrimagnetic substrates

Abstract: The resonant frequency, bandwidth, efficiency and resonant length of a rectangular microstrip resonator on a ferrimagnetic substrate are derived theoretically and are computed for a typical ferrite substrate. The computed values are compared with those of a similar microstrip antenna on a dielectric substrate.

On Design of Coupled Microstrip Lines (Letters)

Abstract: The synthesis approach by Akhtarzad, Rowbotham, and Jones [1] for coupled microstrip lines shows close agreement with the Bryant and Weiss results [2] except for small W/H where the deviation is about 14 percent in computing Z/sub infin/. It is shown that the approach in [1] will produce close agreement with [2] for all W/H when Wheeler's formula [4] for single microstrip line is incorporated in the synthesis procedure.

Microstrip-type antenna

Abstract: PURPOSE:To ensure a wide range of band, by providing an antenna element having a variation modulus nearly adverse to the variation modulus between the phase difference among polarized waves of a certain antenna and the frequency to said antenna. CONSTITUTION:An antenna element 33 is attached to the side of a feeding pattern 32 of a feeder 31. The phase difference between polarized waves (d) and (e) that is caused at a circular polarized wave type antenna 31 ha a negative variation modulus to the frequency. On the other hand, the phase difference between the waves (d) and (e) caused to the element 33 has a positive variation modulus to the frequency. These waves are synthesized to obtain a circular polarized wave antenna having the frequency characteristics of a phase difference.

Wire grid microstrip antenna

Abstract: An antenna, adapted to be used as a monopulse antenna in a guided missile, is shown to comprise four separate microstrip circuits in different quadrants of a circular microstrip arrangement, each one of such microstrip circuits being made up of an array of contiguous rectangular meshes with the widths of the shorter sides of such meshes being varied to provide an amplitude taper

A 40 GHz Microstrip Array Antenna

Abstract: A 40 GHz 4x24 element microstrip array consisting of rectangular microstrip resonators is described. The antenna is developed using scaling techniques. A microstrip feed network is calculated including discontinuity effects. Return loss, bandwidth and radiation characteristics are given.

Circular polarized wave cone beam antenna

Abstract: PURPOSE:To obtain an antenna with cone beam excellent in circular polarized wave characteristics and small occupied volume, by locating a vertical polarized wave antenna and a horizontal polarized wave antenna with a specified distance vertically and giving a signal of phase difference in 90 deg.. CONSTITUTION:A circular type microstrip antenna consisting of a spacer 10 made of a base 9 dielectric substance or the like, a radiating plate 11, and a power feeding line 15 and operating with vertical polarized waves, has a main beam toward the angle of elevator determined in advance to a horizontal plane and forms circular cone beam symmetrical to the vertical axis. Further, a circular loop antenna consisting of a support 12, radiation elements 13, a power feeding line 14 and operating with horizontal polarized waves forms a circular cone beam almost the same that of a circular microstrip antenna. Further, the antennas are located to a specified distance vertically, and a signal with almost 90 deg. of phase difference electrically is given to both the antennas.