Showing papers on "Patch antenna published in 1986"

A reciprocity method of analysis for printed slot and slot-coupled microstrip antennas

Abstract: A method is presented for the analysis of slot-type discontinuities in microstripline. The approach is based on the reciprocity theorem and uses the exact Green's functions for the grounded dielectric slab in a moment method solution for the unknown antenna currents. The method is applied to two specific geometries: a radiating slot in the ground plane of a microstripline, and an aperture coupled microstrip patch antenna. Results for antenna impedance are compared with measurements, and far-zone patterns are calculated. The method is shown to be quite versatile, and should find application to related problems.

Analysis of an aperture coupled microstrip antenna

Abstract: A microstrip patch antenna that is coupled to a microstripline by an aperture in the intervening ground plane is analyzed. Coupled integral equations are formulated by using the Green's functions for grounded dielectric slabs so that the analysis includes all coupling effects and the radiation and surface wave effects of both substrates. A Galerkin moment method solution of the coupled integral equations agrees quite well with measured data. Design data are contained in parameter studies, many of which are verified by experimental results.

An experimental investigation of electrically thick rectangular microstrip antennas

Abstract: The electromagnetic properties of electrically thick rectangular microstrip antennas were investigated experimentally. Antennas were fabricated with different patch sizes and with electrical thicknesses ranging from 0.03 to 0.23 wavelengths in the dielectric substrate. The resonant frequencies were measured and compared to existing formulas. The bandwidth was calculated as a function of electrical thickness and the antenna radiation patterns were measured.

A new model for broadband waveguide to microstrip transition design

Abstract: A new model is presented which permits the prediction of the resonant frequencies created by antipodal finline waveguide to microstrip transitions. The transition is modeled as a tapered transmission line in series with an infinite set of coupled resonant circuits. The resonant circuits are modeled as simple microwave resonant cavities of which the resonant frequencies are easily determined. The model is developed and the resonant frequencies determined for several different transitions. Experimental results are given to confirm the models.

Broadband microstrip antenna

Abstract: An antenna assembly which comprises a first laminar structure which includes a sheet of dielectric material having on one side a contiguous metal sheet and on the other side a strip transmission line adapted to be coupled with signal feeding means, and a second laminar structure, one side of which is in contact with the transmission line, and having on the other side, at least one region but preferable at least two concentrically arranged regions of a coated or cladded metal which serves as a radiator, characterized in that the transmission line is non-symetrically disposed with respect to the radiator.

The Nature of the Leakage from Higher Modes on Microstrip Line

Abstract: Some confusion in the literature is clarified regarding the properties of microstrip line higher modes in the neighborhood of cutoff. It is shown that those modes become leaky in that range, and that the leakage occurs in two forms, a surface wave and a space wave. Numerical values obtained from an accurate analysis are presented that illustrate the nature of the leakage for microstrip lines with either open or covered tops.

The effect of various parameters of circular microstrip antennas on their radiation efficiency and the mode excitation

Abstract: The numerical solution of circular microstrip antenna is carried out using the method of moment. The effect of the probe position, The dielectric permittivity of the substrate, and the substrate thickness on the radiation pattern and the mode excitation efficiency are studied. It is found that the probe position and the patch size can be used to control the mode excitation efficiency, and heigher order modes can be generated using only one feed location. Also, the finite ground plane can be used to improve the symmetry of the radiation patterns. The technique is general and can be used to investigate other scattering and antenna problems involving axisymmetric geometries.

Characteristics of a radial line slot antenna for 12 GHz band satellite TV reception

Abstract: Characteristics of a novel planar antenna which can radiate a circularly polarized pencil beam in x -band are presented for the application of receiving direct broadcast from a satellite. This antenna belongs to a class of slotted waveguide antennas and promising performances, especially its high efficiency, have already been predicted theoretically. The measured performance of a model antenna with a diameter of 0.6 m, is presented. Antenna gain of about 35 dBi and axial ratio of about 1 dB are realized at 12.2 GHz; the associated antenna efficiency of 57 percent is very high in comparison with that of the conventional microstrip antennas, in this range of gain.

Conformal antenna and method

Abstract: An antenna assembly and a method for mounting an antenna element in full conformity to a substantially curved surface are disclosed. The method includes the steps of providing a first, relatively thin dielectric substrate portion having an antenna element formed on a surface thereof; providing a second, relatively thick dielectric substrate portion; shaping and securing the second substrate portion to the curved surface; and shaping and securing the first substrate portion and the antenna element to the second substrate portion. The method permits a microstrip antenna, or other thin structure supported on a substrate, to be mounted to curved surfaces of even short radius or curvature (e.g., less than four inches) in full conformity therewith without damaging the thin fragile antenna element.

Dual band slotted microstrip antenna

Abstract: A dual band microstrip antenna including a slotted microstrip radiating pllel to and spaced from a ground plane with dielectric material therebetween, the slotted microstrip radiating and having a first resonance corresponding to the dominant radiation mode that would occur in an unslotted microstrip and a second resonance created by the slot. The polarizations of the two resonances are perpendicular to each other with the slot resonance being polarized along the centerline of the slot.

Input impedance of a probe-fed circular microstrip antenna with thick substrate

Abstract: A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included.

Analysis of arbitrarily shaped microstrip patch antennas using segmentation technique and cavity model

Abstract: Arbitrarily shaped microstrip patch antennas have been analyzed for resonant frequency, input impedance, and radiation patterns. The segmentation technique and the cavity model have been used for this purpose. The usefulness and the accuracy of the method are shown through comparison with experimental results for a rectangular ring antenna. The agreement is seen to be very good. Ihe method appears to be more efficient compared to those reported so far for arbitrary shapes. Moreover, feed reactance is built into the analysis. The method presented here can also be used to analyze microstrip antennas with various types of loadings, e.g., shorting pins, matched loads, etc.

Antenna with integral tuning element

Abstract: A patch antenna, which may be one element of an antenna array, is formed on one broad surface of a semiconductor plate. A ground plane is formed on the second broad surface. This semiconductor is doped in regions near a periphery of the patch to define a semiconductor PN junction have electrode contacts to the patch and to the ground plane. The junction has capacitance which tunes the patch antenna. The characteristics of the junction are controlled by bias to selectively tune the patch antenna. The bias is a direct voltage in one embodiment of the invention. In another embodiment, the junction work function itself provides a bias which is controlled by temperature control of the diode.

A New Method for Measuring Dielectric Constant Using the Resonant Frequency of a Patch Antenna

Abstract: An analytical expression is given for the resonant frequency of a rectangular patch antenna. It shows explicitly the dependence of the resonant frequency on the characteristic parameters of a patch antenna. Based on this result, a new method is developed for the measurement of the dielectric constant of a thin slab substrate. Basically, the test equipment consists of a rectangular microstrip antenna the patch of which is fed either by a microstrip line or coaxial line. From the measured resonance parameters of the rectangular patch antenna, the dielectric constant can be easily obtained. The measured values of the present method are in agreement with the precision standard cavity resonator method. Accuracy of the dielectric constant so obtained is satisfactory.

Effect of substrate on the efficiency of an arbitrarily shaped microstrip patch antenna

Abstract: A general approach is presented for the determination of power radiated via the space wave and surface wave from the aperture of an arbitrarily shaped microstrip antenna. The magnetic current model is used for this, and the analysis is carried out in the Fourier domain to determine the effect of the substrate. It has been shown that, in the Fourier domain, the longitudinal components of electric and magnetic displacement vectors follow the transmission line equation and can be solved by inspection. An expression for total radiated power has been derived. The singularities of the integral for power radiation indicate the presence of surface wave modes, and the associated power has been obtained using a singularity extraction technique. The effect of the substrate on space wave power has also been determined. This theory has been applied to a rectangular patch antenna. The results are in conformity with those reported in the literature. It has been found that for the frequency range ( h/\lambda, ), the effect of dielectric substrate can be neglected.

Multioctave bandwidth log-periodic microstrip antenna array

Abstract: The application of the log-periodic technique to the series-fed electromagnetically coupled overlaidpatch array allows antennas with flat conformal characteristics and wide bandwidths to be obtained. A k-s analysis of this and other microstrip array types indicate that the microstrip patch is not an optimum element for log-periodic arrays and that direct connection will result in arrays having a limited bandwidth. The addition of series capacitance to the patch equivalent circuit, implemented by electromagnetic coupling, allows an optimum to be approached. Log-periodic overlaid patch array design and measured results for an array with a 4:1 bandwidth are presented. These, together with a transmission-line analysis, indicate the array-design trade offs available and that the ultimate bandwidth is limited primarily by changes in the input return loss and radiation pattern due to the use of uniform thickness substrates.

Experimental study on stacked triangular microstrip antennas

Abstract: The broadband behaviour of a pair of stacked triangular microstrip antennas is investigated experimentally. Recent experiments have shown that the bandwidth of a triangular microstrip antenna (TMA) can be broadened to as high as 17.5%.

Aperture-coupled microstrip antenna with a perpendicular feed

Abstract: A new technique is described for feeding printed antennas. A microstrip antenna on one substrate is coupled through an electrically small aperture to a microstrip feed line on a perpendicularly oriented substrate. No direct connection is made to the patch. Such a geometry allows two separate substrates to be used for the antenna and feed functions. Measurements of a prototype design are presented.

Microstrip balun-antenna apparatus

Abstract: An balun-antenna arrangement is provided which is capable of being fabricated on a printed circuit board by automated equipment. The balun-antenna includes a microstrip transmission line which is coupled to one end of a split microstrip transmission line having opposed ends. An antenna which is symmetric about its feedpoint is coupled to the remaining end of the split microstrip transmission line.

Dual band antennas with microstrip array mounted atop a slot array

Abstract: A primary slotted array antenna operates at 10 GHz. In front of the primary antenna there is disposed a secondary antenna which operates at 1 GHz and is substantially transparent at 10 GHz. The secondary antenna is formed by an array of patch radiators and a transmission line feed network. The radiators and feed network are all formed by a conductive grid sandwiched between dielectric layers and designed to achieve the transparency at 10 GHz. At 1 GHz the grid appears as a continuous conductor forming one conductor of a microstrip transmission line. The other conductor (ground plane) is formed by the conductive front surface of the primary antenna. The grid/dielectric sandwich is suitably spaced from the ground plane by low dielectric pads. Other embodiments use slotline or coplanar stripline techniques. The ground plane may be an integral part of the secondary antenna, also constructed to be transparent at primary frequency.

Aperture-coupling of a rectangular microstrip resonator

Abstract: A theory and experimental results for the aperture coupling of rectangular microstrip resonators are presented. The resonator is coupled by a resonant slot in the ground plane to a microstrip feed line.

Stacking resonators to increase the bandwidth of low-profile antennas

Abstract: A method of increasing the bandwidth of low-profile cavity-hacked slot and microstrip patch antennas without appreciably adding to the antenna dimensions is presented. This idea incorporates the stacking of structures which have close resonant frequencies. Energy is coupled between cavities via carefully placed slots in the common wall. An approximate two-and-a-half fold increase in input impedance bandwidth has been observed for a certain cavity-backed slot antenna.

Rectangular microstrip antenna for circular polarization

Abstract: Richmond's reaction integral equation method is used to design a rectangular microstrip patch to produce a circular polarization. A rectangular patch with the aspect ratio a = W_{x}/W_{y} , in the range 1.015- 1.02 and corner fed by a microstrip line, produces circular polarization. For substrate with thickness d = 0.16 cm, a = 1.017 the nearly square patch gives maximum bandwidth.

Connectorless antenna coupler

Abstract: A metal shield is dimensioned to enclose a portion of a portable radio having an internal antenna and a first transmission line. A transmission line mounted in the shield is positioned to be adjacent to the first transmission line when the shield engages the radio and permits energy to be coupled between the resonator and the first transmission line. The first transmission line and the shield are dimensioned so that the electrical length of the first transmission line increases to 2L when the shield engages the radio, where L is the electrical length of the first transmission line when the shield does not engage the radio. This electrical length transformation by an integral multiple of one half wavelength helps to maintain the input impedance to the internal antenna.

Two-frequency slotted planar antenna

Abstract: A two-frequency planar antenna incorporates a resonant antenna and a slot antenna which are arranged in a superposed manner on the same dielectric substrate so as to be operable independently without interfering with each other. The two-frequency planar antenna includes a front conductor plate arranged on one surface of a dielectric substrate to serve as a radiation conductor plate of a resonant antenna and a slotted conductor of a slot antenna, a back conductor plate arranged on the other surface of the dielectric substrate to serve as a grounding conductor of the resonant antenna and a reflector of the slot antenna, and a slot antenna feed line embedded in the dielectric substrate. The slot antenna feed line is arranged along an axis where an electric field in an excitation mode of the resonant antenna is reduced to zero and at least one slot is formed in the front conductor plate along the feed line.

Flat wide-band antenna

Abstract: An antenna for receiving or transmitting electromagnetic waves with circular polarization or, in certain configurations, linear polarization. The antenna element is low-cost, wide-band and medium-gain broadside antenna element which may be used alone or in arrays. One embodiment disclosed comprises a wire or micro-strip conductor outlining a cruciform shaped loop parallel to a conductive plane from which it is separated by a dielectric layer. The lengths and widths of the branches of the cruciform loop are chosen to be λg/2 and λg/N respectively, where λg is the guide wavelength of the radiative transmission line formed by the conductor and plane. The antenna element is applicable to mobile earth-bound terminals for selective communications, for example.

Shorted microstrip antenna with multiple ground planes

Abstract: A low and broadband shorted microstrip antenna is disclosed which is mainly applicable to a mobile body in a mobile communication system. A first grounding conductive sheet which faces a radiating conductive sheet is provided at both ends thereof with a second and a third grounding conductive sheets which are perpendicular to the first grounding conductive sheet, whereby a beam tilt characteristic of the antenna is improved. The passive element and a conductive stub are disposed atop the grounding conductive sheet. The passive element and the conductive stub face the radiating conductive element and serve to improve the impedance matching parameter of the microstrip antenna.

Slow-Wave Characteristics of Ferromagnetic Semiconductor Microstrip Line

Abstract: A new slow-wave microstrip line made of a ferromagnetic semiconductor (FMS) substrate is proposed and its characteristics discussed. It is shown that this structure has more desirable and flexible guided wave properties than the conventional metal-insulator-semiconductor (MIS) microstrip line.