Showing papers on "Feed line published in 1990"

Dual frequency antenna feed with apertured channel

Abstract: A dual band feed arrangement for a microwave antenna provides microwave communication in a lower band and in a substantially widened upper band to provide simultaneous microwave communication for three signals. One signal in the lower band propagates between the outer and inner conductors of a coaxial waveguide in the TE11 coaxial mode, and two signals in the upper band propagate in the inner conductor in TE11 circular waveguide mode. A combiner, having a conically shaped section with a plurality of irises through its sidewall, is coupled to the coaxial waveguide to provide a transformation from the TE11 modes to the HE11 waveguide modes for each of the three signals. A dielectric rod extends from within the inner conductor and into the horn antenna for propagating the second signal out of and into the antenna.

Tapered slot antenna with balun slot line and stripline feed

Abstract: An exponentially tapered slot (Vivaldi) antenna for producing an end-fire beam. The antenna features a novel balun for coupling with a feed line. The conventional Vivaldi antenna is fed by means of a stripline section (1) underlying the ground plane (5) and lying perpendicular to the axis of the slot line (3). This balun arrangement has an inherent narrow bandwidth. In the proposed antenna arrangement the slot line (14) and the stripline (16) each have a 45° twist centered on a common cross-over point (X o ,Y o ). The stripline (16) is terminated by a short-circuit to the ground plane (12) and the slot line (14) is terminated by an open-circuit in the form of a circular slot (15). The E-plane and H-plane radiation characteristics are similar to those of the conventional Vivaldi antenna, but the arrangement has a broadband capability enabling operation over any 3 to 1 bandwidth in the frequency range 1 to 40 GHz.

Microwave hyperthermia applicator

Abstract: The antenna system of the invention is insulated on the outside and when inserted in a dissipative medium has a fixed complex resistance. When the antenna is supplied with HF energy through a coaxial cable, only that area of the medium immediately around the antenna is heated. The area surrounding the insulated HF feed line is not heated, or such heating is negligible, since, owing to the fixed complex resistance of the antenna in the medium, any return of energy along the feed line is prevented. The antenna system of the invention is suitable for use in the tumor-therapy field as a hyperthermic microwave applicator for limited local heating of cancerous tissue.

Guidelines for design of electromagnetically coupled microstrip patch antennas on two-layer substrates

Abstract: Graphical guidelines for design of electromagnetically coupled square and circular microstrip antennas are given. Substrates composed of two different dielectric layers are considered. The analysis is extended to electrically thick substrates. Given the required resonant frequency and the bandwidth, material parameters are selected. Patch dimension and the optimal position of the feed line are obtained from the provided graphs. The design data were computed by applying the method of moments in the spectral domain to solve the integral equation for the currents on the patch and portion of the microstrip feed line. The integral equation was formulated using the appropriate dyadic Green function for the grounded multilayered slab. >

Space-saving two-sided microwave circuitry for hybrid circuits

Abstract: A space-saving, two-sided microwave transmission line for hybrid circuits is disclosed, wherein a microstrip or coplanar waveguide RF line is formed on the front side and a microstrip or coplanar waveguid RF transmission line is formed on the backside of a hybrid circuit board containing other components. The RF line is formed on the top side of the circuit board to facilitate connections to other circuit boards and/or RF components, but is routed underneath the board to traverse the areas of the board occupied by other components. When the RF line is on the top side of the substrate, the groundplane is established by the metal layer on the bottom of the substrate for a microstrip line and by a top metal layer for a coplanar waveguide line, and when the RF line is on the bottom of the substrate, the groundplane is established with the metal layer on top of the substrate for a microstrip line, and with the bottom metal layer for a coplanar waveguide line. The connection from the topside and backside RF lines is accomplished by low VSWR plated via holes through the substrate.

Long rectangular patch antenna with a single feed

Abstract: Radiation characteristics of a long rectangular patch antenna excited by a single feed are investigated. The equivalent circuit of the patch including the feed line section is developed. It is found theoretically that a single feed long rectangular patch supports a leaky traveling wave along the length of the patch. The complex propagation constant of the traveling wave is estimated by solving the wave equation with impedance boundary conditions. Radiation patterns of the antenna are obtained using the principle of equivalence. Various radiation characteristics of center-fed and end-fed long patch antennas are presented. >

RF tuning element

Abstract: A device for tuning a circuit includes a substrate, a transmission line on the substrate that includes first and second conductors coupled to a circuit to be tuned, and a movable short-circuit for varying the impedance the transmission line presents to the circuit to be tuned. The movable short-circuit includes a dielectric layer disposed atop the transmission line and a distributed shorting element in the form of a conductive member that is configured to be slid along at least a portion of the transmission line atop the dielectric layer. The conductive member is configured to span the first and second conductors of the transmission line and to define at least a first opening that spans the two conductors so that the conductive member includes first and second sections separated by the first opening. The first and second sections of the conductive member combine with the first and second conductors of the transmission line to form first and second low impedance sections of transmission line, and the opening combines with the first and second conductors of the transmission line and the dielectric layer to form a first high impedance section of transmission line intermediate the first and second low impedance sections. Each of the first low impedance section and the first high impedance section have a length along the transmission line of approximately one-quarter wavelength, thus providing a periodic variation of transmission line impedance. That enhances reflection of rf power.

Planar microwave antenna for producing circular polarization from a patch radiator

Abstract: A planar antenna is described which employs a thin patch of conductive material supported above and substantially parallel to a closely spaced thin conductive ground surface. Two or more narrow slots are positioned in the ground surface beneath the conductive patch. A microstrip transmission line, placed below the ground surface, excites the slots in series. The length of the microstrip line between the slots, the position of the microstrip line across the slots, and the dimensions of the slots are chosen to excite two orthogonal modes in the conductive patch in phase quadrature. This excitation results in a planar antenna which receives and transmits electromagnetic waves of circular polarization. The antenna may also employ a coplanar waveguide transmission line instead of the aformentioned microstrip transmission line. The coupling apertures then form slot discontinuities in series with the coplanar transmission line, which are positioned under the conductive patch. The antenna may also employ several conductive patches stacked over each other in a parallel fashion to enhance antenna performance.

Broadband microwave slot antennas, and antenna arrays including same

Abstract: A broadband microwave antenna exhibiting high radiation efficiency over a broad frequency band in which the VSWR is less than 2.5:1 over at least 15% of the frequency band, includes a ground plane at one side of a dielectric substrate and formed with at least one slot, and a feed strip at the other side of the substrate. The feed strip is of uniform width for substantially its complete length, but includes a change in width at the feed end of the slot to produce a first impedance matching network effective to bring the slot impedance to the level of the feed line over the broad frequency band, and another change in width at the load end of the slot to produce a second impedance matching network which reduces the slot reactance to match the reactive impedance of the load to the reactive part of the slot impedance over the broad frequency band.

Portable transmitter apparatus for inducing alternating current in a buried metallic line

Abstract: A system of apparatus for locating underground metallic lines includes a transmitter apparatus at a first work station above ground for inducing a current in the line and a receiver at a second work station for making field measurements. The transmitter apparatus includes a battery-powered transmitter circuit supported from a portable housing, a ferrite core antenna incorporated within the transmitter circuit, and a separate tank circuit which includes a loop antenna and a capacitor and is tuned to a predetermined operating frequency and is electrically isolated from the ferrite core antenna. The ferrite core antenna transfers energy through a magnetic flux field to the loop antenna, and a magnetic field generated from the loop antenna inductively creates an alternating current in the line which then generates an alternating electromagnetic field about the line at the second work station.

Circularly polarized antenna with resonant aperture in ground plane and probe feed

Abstract: A cavity-backed dual-slot antenna element for circular polarization having a single probe extending from the end of the feed line for the element and arranged to couple energy into the resonant slots. The probe lies in the plane of the feed line and has the form of an open circle having a circumference of approximately one wavelength at the operative frequency. The probe is constrained to lie within the boundary of the resonant slots as projected onto the plane of the feed line. The arrangement produces a circular polarization having a greater axial-ratio bandwidth than that of conventional antennas using two orthogonal probes or using a single probe feeding a resonant patch. An antenna comprising a flat array of the elements is suitable for use in DBS (Direct Broadcast by Satellite) TV reception. However, the probe itself is not limited to use in slot antennas and it has applications in other antennas or couplers for circular polarization.

Pane antenna having an amplifier

Abstract: An active window pane antenna for use in motor vehicles includes an antenna conductor arranged on the window pane and being connected via a conductor of negligible length to an input terminal of an active four terminal network also arranged on the pane. The output terminals of the network are connected via a first section of a transmission line to an antenna connector whose ground contact is connected for high frequencies to a ground point on the body of the motor vehicle. The impedance of the first section of the transmission line is not negligible for the received frequency bands and the input impedance of the four terminal network is balanced with respect to the first section. A second section of the transmission line extends from the antenna connector to a receiver.

Antenna device shared by three kinds of waves

Abstract: An antenna device shared by three different waves has a single two-stage collinear antenna constituted by half-wave dipole antennas which are adapted for a vehicle telephone signal and are stacked one upon the other. The device allows an AM-FM radio receiver to receive AM and FM broadcast signals via a first coaxial cable and a vehicle telephone transceiver to receive a telephone signal via a second coaxial cable. A first impedance converting circuit is implemented as a field effect transistor and connected to the base end of the antenna for matching the antenna and the first coaxial cable in the event of reception of the AM broadcast signal. A second impedance converting circuit matches the antenna and the first coaxial cable at the time of reception of the FM broadcast signal. The impedance converting circuits convert the input/output impedances of the AM and FM signals. The antenna has an antenna rod extending from the base end thereof, a feed tube electrically connected to the antenna rod, and an adjusting feed tube electrically connected to the feed tube and slidably mounted at one end thereof to one the terminating end of the feed tube, and formed with a feed point at the other end. The adjusting feed tube is adjustable in position in its sliding direction to adjust the input/output impedance of the telephone signal as measured at the feed point.

Feed optimization for the slotted line antenna for high-density plasma production

Abstract: Investigations on the optimization of feed structures for exciting the slotted line antenna for high-density plasma production are presented. Each feed structure used (except the direct feed) excites a preferred component of the wave electric/magnetic field. It is seen that the efficacy of plasma production using the different feeds depends directly on the relative importance of the field components (which the feeds excite) for the flow wave mode of the antenna. The optimal feed is shown to be a dipole antenna, oriented so as to excite the radial component of the electric field within the slotted line structure. The plasma characterization results as a function of the input microwave power and the magnetic field in the antenna region are also presented and discussed. The ability of the antenna to maintain high-density plasmas well away from electron-cyclotron resonance is demonstrated. >

Frequency domain integrating resonant superconducting transmission line detector

Abstract: A Frequency Domain Infrared Superconducting Transmission Line (FIRST) detector is comprised of a folded superconducting transmission line 18 coupled at an input port 18a to a narrow band microwave source and coupled at an output port 18b to a microwave power monitor 22. An optically induced change in the kinetic inductance of the transmission line shifts the transmission line phase velocity and resonant frequency. The shift in resonant frequency attenuates the propagating wave amplitude proportionally to the product of the transmission line Q and the frequency shift. When fabricated with a densely folded superconducting line and operated at a nominal resonant frequency of several GHz the use of either linear or logarithmic Schottky barrier detectors enables a realization of a dynamic range of eight orders of magnitude.

Electronically tuned VHF/UHF matching network

Abstract: A matching network matches an output impedance of a source with an input impedance of a load. The matching network includes a plurality of transmission line stubs. Each transmission line stub includes a first transmission line conductor, a second transmission line conductor running parallel to but not in electrical contact with the first transmission line conductor, and ferrite dielectric material between the first transmission line conductor and the second transmission line conductor. A magnetic field is used to vary the relative permeability of the ferrite dielectric material.

On the EMC dipole feed-line parasitic radiation

Abstract: A rigorous analysis of the electromagnetically coupled microstrip dipole based on potential integral equations, Green's functions, and the moment method is presented. The computations of the antenna's radiated field using the steepest descent technique is then detailed, and the theoretical results are compared with experimental measurements in the X-band. By considering the feed as an antenna part, the excitation line parasitic radiation is shown clearly. Two possibilities to reduce this parasitic phenomenon are proposed. Also, it is shown that in any microstrip structure (one or two layers) excited by a microstripline, the feed parasitic radiation is nonnegligible. >

Three-dimensional patch antenna array

Abstract: A patch antenna array disposed on a curved surface (2), the array comprising a series of planar linear arrays (3a, 3b) of interconnected patches (1) coupled to food lines (4a, 4b) disposed around the curvature of the surface and interconnecting the linear arrays in a direction transverse to the line of the arrays, the effective separation of the patches along each feed line and hence the input signal phase difference between adjacent patches being adjusted to correct for the curving of the array and thus generate a linear wave front giving a well-formed output beam.

High frequency coaxial line coupling device

Abstract: A high frequency coaxial line coupling device which is insertable along the length of a coaxial line such as that which connects a rotary antenna carried on a moving body such as vehicle or vessel to receive a signal from a communication or broadcast satellite, with a receiver component such as tuner fixed to the moving body, for the purpose of allowing free relative rotation of the two segments of the coaxial line separated by the coupling device and preventing twist or entanglement of the coaxial line caused by rotation of the antenna with turning movement of the moving body. The device structure provides for a low transmission loss characteristic over a wide frequency range.

Radio frequency antenna for a nuclear magnetic resonance tomography apparatus

Abstract: A radio frequency antenna for a nuclear magnetic resonance tomography apparatus has interior conductors which form a transmission line resonator with at least one shortening capacitor. The transmission line resonator can resonate at a plurality of resonator frequencies, and a trap circuit is provided for decoupling the interior conductors from the other conductors. The antenna can be operated at a number of different resonate frequencies, for example, at frequency f1 =170 MHz for protons (hydrogen) and F2 =69 MHz for phosphorous.

Hydraulic system with filter - separates out fine particles by channelling part of flow through by=pass line

Abstract: The hydraulic pump (2) is connected to a reservoir (1) by an inlet line (4) at one end and to a high pressure line (6) by a feed line (5) at the other. The high pressure line (6) splits into two sections (8,9). One section (8) takes most of the output to the user. The other (9) is a bypass with a regulatorm (11) which channels flow into a line (13) which splits into two sections (15,14). One section (15) leads to a fine-superfine filter (18), via non-return valve (19) to line (17) and reservoir (1). The other section (14) passes via relief valve (16), which opens at a pre-determined pressure, to the line (17) carrying the filtered medium. ADVANTAGE - The filtration system is relatively cheap and easy to fit and remove. It allows hydraulic fluid to be used for much longer periods than in current systems.

Analysis of slot-coupled double layer microstrip lines

Abstract: An analysis of slot-coupled double layer microstrip lines is presented. A modal field expansion method and the Poynting theorem are applied to derive the input impedance as seen by the feed line at the slot. By comparing the theoretical results with measured values, the accuracy of the method is verified.

Radar antenna array

Abstract: For a radar antenna array having a supply line which is connected via a T/R cell to a transmitter and a receiver and, during transmission, distributes the transmission signal to double radiating-element rows and, via 3dB couplers, to the radiating elements of the two individual rows of each Doppler row which are polarised orthogonally with respect to one another, an additional receiving line is provided, which is likewise connected to the 3dB couplers. The antenna can be operated via controllable phase shifters both with two independent polar diagrams of orthogonal polarisation and with a single polar diagram of selectable polarisation. The received signals which are obtained via the supply line and the receiving line can advantageously have superimposed on them an adjustable amplitude weighting and phase shift so that, for example, the received polarisation can be set independently of the transmitted polarisation. By adding an additional distribution device to the supply line and/or to the receiving line to form a conductor network, the antenna can be extended for monopulse operation.

Progressive phase-Rotman-Turner lens feed transmission line network

Abstract: A progressive phase feed transmission line network for use with a Rotman-Turner lens is composed of a plurality of feed ports for receiving or transmitting energy from or to the lens, a pair of control ports, a plurality of different sets of transmission line segments with the segments in the same sets being of substantially equal lengths, and a plurality of power directors for splitting or combining energy depending upon whether the network is operating in a "receive" or "transmit" mode Different phase delays are interposed in the network to provide a passive arrangement which can operate in the "receive" mode to determine directionality of energy received by an antenna array and fed through a Rotman-Turner lens to the transmission line network or can operate in the "transmit" mode in combination with adjusting of a phase shifter to directionally steer the energy launched into space by the antenna array after being fed from the network through the lens to the antenna array

Transmission line network for multiple capacitive loads

Abstract: An improved transmission line network includes a transmission line connecting a signal source to a plurality of capacitive loads. Preferably, the transmission line is not terminated with its characteristic impedance. The transmission line may include capacitance added for the purpose of smoothing the rising or falling edge of signals distorted by reflections from the far end of the network. In addition, the transmission line network preferably includes resistance added in series with the transmission line for the purpose of dissipating reflections from the far end and thereby reducing distortion upstream from the series resistors. The capacitive loads may be connected to the transmission line through series resistors, the magnitudes of which are selected to obtain uniform rise or fall times at all loads.

Impedance matched coaxial transmission system

Abstract: A coaxial transmission line system includes a coaxial transmission line having a center conductor and an outer conductor, and an rf generator. A stub antenna is coupled to the generator, and extends radially into the transmission line between the outer and center conductors for capacitively coupling rf energy from the generator to the center conductor. Input impedance of the coaxial transmission line is matched to the impedance of the antenna and generator by means of a pair of tuning screws that extend radially into the transmission line between the outer and center conductors adjacent to the antenna. The tuning screws are adjustably positionable radially of the center conductor and are spaced from each other lengthwise of the transmission line.

Optical receiver for subcarrier frequency division multiplexing signals

Abstract: The optical receiver includes a photodiode, a preamplifier and a length of transmission line. The photodiode may be connected to the preamplifier, either via the transmission line, or directly between the preamplifier and the transmission line, that is, the transmission line is connected as an open circuit. The transmission line 14 may comprise a coaxial cable, stripline, or any other suitable form of transmission line. The input impedance of the preamplifier should be designed to match the characteristic impedance of the transmission line. The noise of the preamplifier associated with the transmission line has a periodic spectrum dependent upon the length of the line with peaks at odd multiples of f' and minima at even multiples of f'. The value of f' is related to the length of the transmission line in accordance with: f'=v/4L where v is the propagation velocity, typically 2/3 the speed of light, and L is the length of the transmission line.

Theoretical and experimental analysis of a circularly polarized notched antenna fed electromagnetically by one microstrip line

Abstract: A notched antenna electromagnetically coupled with only one microstrip line has been designed to obtain circular polarization. This configuration presents two advantages. First, only one feed line is used, as opposed to usual designs where two microstrip lines are required. This leads to less cumbersome realizations and to simpler antenna arrays. Second, it retains the monolithic concept of integrated circuits: the feed line and the radiation elements are realized with the same technology and are thus simpler to manufacture. The notched antenna has been rigorously and completely analyzed using an integral equation technique. The experimental results are in good agreement with theoretical predictions in X band. The quality of the circular polarization is shown to be very sensitive to the dimension of the notches, and the frequency range for which the ellipticity rate is acceptable is rather small. >

Triplet plane antenna

Abstract: PURPOSE: To improve efficiency by specifying position relationship among a radiant element and a slot, shape, and size. CONSTITUTION: The radiant element 4 and the slot 3 are arranged at an equal interval in two directions intersecting orthogonally to each other, respectively, and also, an arranging interval (d) is set at a value of 0.85-0.93 times the free spatial wavelength λ 0 of the center frequency of a frequency band area in use. Also, by forming the shape of the slot 3 in a square whose one side is set at the length of 0.48-0.65 times the wavelength λ 0 , the unrequired radiation of a feed line can be suppressed by arranging the phases of waves radiated from neighboring slots, and also, the efficiency of an antenna can be further neightened by employing a parasitic element. COPYRIGHT: (C)1992,JPO&Japio

Hyperthermic microwave applicator

Abstract: The antenna system of the invention is insulated on the outside and when inserted in a dissipative medium has a fixed complex resistance. When the antenna is supplied with HF energy through a coaxial cable, only that area of the medium immediately round the antenna is heated. The area surrounding the insulated HF feed line is not heated, or such heating is negligible, since, owing to the fixed complex resistance of the antenna in the medium, any return of energy along the feed line is prevented. The antenna system of the invention is suitable for use in the tumour-therapy field as a hyperthermic microwave applicator for limited local heating of the cancerous tissue.