Showing papers on "Coaxial antenna published in 1979"

Hybrid mode waveguide or feedhorn antenna

Abstract: The present invention relates to a hybrid mode waveguide or feedhorn antenna for transforming the TE 11 mode into the HE 11 mode. The waveguide or antenna comprises a first waveguide section of uniform cross-section at the TE 11 mode entrance port which in the antenna arrangement changes to a second section which flares outward toward the antenna mouth, and a spiro-helical projection bonded with a dielectric layer to the inner surface of the waveguide or antenna. The spiro-helical projection comprises a closely spaced helically wound wire structure formed of dielectrically coated wires which in the first section decrease in gauge size in small adjacent portions thereof as the helix progresses away from the TE 11 mode entrance port and in the remainder of the helical projection, the same or decreasing gauge wire in adjacent portions can be used.

Multiple band circularly polarized microstrip antenna

Abstract: Disclosed is a multiple band antenna assembly for communicating electromagnetic radiation. An antenna element stack is constructed of a plurality of elliptical lamina antenna elements mutually separated by layers of dielectric material, and separated from a ground plane by dielectric material. The antenna assembly is coupled through a feed line in contact with the top antenna element. A conductor joins the remaining antenna elements to the ground plane. Each individual antenna element is operable for communication reception and transmission within a frequency band determined by the size of the particular antenna element. The antenna elements are arranged in order of decreasing size with the largest antenna element closest to the ground plane. The sizes of the antenna elements may be selected to provide electromagnetic radiation communication over several distinct frequency bands, or to connect the individual bands into a broad band.

Coaxial dual antenna connection arrangement for communications apparatus

Abstract: Apparatus having an integral coaxial antenna coupled via a coaxial connector to its internal circuitry has a coaxial switch/connector for alternatively coupling an external coaxial signal source to the internal circuitry, thus reducing impedance mismatch to a minimum with no impedance matching network required.

A Novel MIC Slot-Line Antenna

Abstract: A new Microwave Integrated Circuit (MIC) slot-line antenna has been developed. This is intended for application in short range radar and phased array systems. The new antenna can replace the conventional MIC dipole and resonator antennas with its distinct advantages of a sharper beam for the same order of gain. The antenna is light, compact, easily reproducible and could be integrated with rest of the MIC circuitry. The antenna operates in the X-band with a gain of 6 dB and a side lobe level of 10 dB. The radiation characteristics of the antenna are controllable.

Analysis of a circular-disc printed-circuit antenna

Abstract: The input impedance and the electromagnetic fields of a circular-disc printed-circuit antenna are found. The antenna is driven at an arbritrary point. The present analysis takes into account the radiation through the side wall and the fringe field at the edge of the printed-circuit antenna.

Antenna feed system for receiving circular polarization and transmitting linear polarization

Abstract: An object is to provide for receiving a circularly polarized signal from an antenna feed (10) connected to orthogonally spaced antenna elements (11, 12, 13, 14) and for transmitting a linearly polarized signal through the same feed without switches, and without suffering a 3 dB polarization mismatch loss, using an arrangement of hybrid junctions. The arrangement is comprised of two dividing hybrid junctions (15, 16), each connected to a different pair of antenna elements and a summing hybrid junction (17). In one embodiment, a receiver (18) is connected to the summing hybrid junction directly. A diplexer (19a or 19b) is used to connect a transmitter (20a or 20b) to only one pair of antenna elements. In an alternative embodiment, designated left and right circularly polarized (LCP and RCP) transmitters (21, 22) are connected to the summing hybrid junction by separate diplexers (23, 24), and separate LCP and RCP sensitive receivers (25, 26) are connected to the diplexers in order to transmit linearly polarized signals using all four antenna elements while receiving circularly polarized signals as before. An orthomode junction (30) and horn antenna (32) may replace the two dividing hybrid junctions (15, 16) and antenna feed (10).

Aircraft television antenna receiving system

Abstract: An omnidirectional VHF television antenna system for an aircraft which includes one pair of slot antennas on each side of the aircraft vertical fin. Each pair of antennas includes a VHF high band slot antenna and a VHF low band slot antenna. Due to co-channel interference the antenna system includes a left, right or omnidirectional azimuth response characteristic selectable by a cabin attendant through control of the antenna system antenna pattern select switch. The VHF low band slot antennas are tilted from the vertical by about 24° and the VHF high band slot antennas are disposed vertically. Signal processing circuit means coupled between the slot antennas and the antenna system output terminal includes solid state switches to select antenna coverage omnidirectional and azimuth, or to the left or right of the aircraft to minimize ghosts or co-channel interference.

The omni microstrip antenna: a new small antenna

Abstract: The omni microstrip antenna is a microstrip-shorted quarter-wave resonator that is wrapped around a cylinder. It is an electrically short antenna, and it can be made to radiate an omnidirectional pattern normal to the axis of the cylinder. Equations governing the design of the antenna are given along with a method of excitation. An example of a design at 41.4 MHz is given, and experimental results are reported.

Modified circular microstrip antenna elements

Abstract: The addition of radial conducting strips to microstrip disc antenna elements alters the circuit and radiation behaviour. Frequency shift, pattern modification and dual-frequency operation can be obtained by proper selection of the strip parameters.

Antenna for scanning a limited spatial sector

Abstract: A feed system for scanning focal plane antenna systems with which a variable focal spot illumination may be achieved within the focal region of a primary antenna over a limited scanning sector is disclosed. An array of collector elements positioned to receive radiation from a scannable feed antenna is coupled to an array of radiator elements positioned in the focal region of the primary antenna, the positioning of the radiator and collector elements are such that the focal spot illumination is caused to vary with the scan angle of the antenna.

Lens-type compact antenna range

Abstract: A compact antenna range is described which uses a plastic foam lens to obtain a collimated beam within which the radiation pattern of a test antenna can be measured. A novel feature is the introduction of a controlled amount of loss into the lens so that a nearly uniform electric field is measured over a high proportion of the lens aperture.

Reduced Size Spiral Antenna

Abstract: The cavity backed spiral antenna with a square configuration is described. It is shown that with continual development and an invention of a unique design of cavity the aperture of this type of antenna is reduced to approximately 0.1? square at its lowest operating frequency. The antenna radiates circularly polarised energy with a uni-directional beam over a decade frequency band. It is shown that the match of the antenna is better than 2:1 over the entire frequency band and that its gain is relatively high when its aperture dimensions are taken into consideration.

Stub matched antenna and method of feeding same

Abstract: An antenna having a unique method of feed is comprised of a vertical radiator and a driven element. The driven element is defined by an integral, substantially straight part. RF energy is fed into or extracted from the antenna by a coil perimetrically wound around the straight part of the driven element. Preferably, this coil is comprised of the exposed, insulated inner conductor of a coaxial cable. The coil covers a relatively large segment along the periphery of the driven element giving rise to unique electrical properties. With this method of feed, the antenna exhibits good bandwidth and requires no metal-to-metal contact between feedline and antenna.

Plane wave spectrum scattering analysis of near-field obstacle effects on directive antenna patterns

Abstract: A plane wave spectrum scattering analysis of the effects of a near-zone obstacle on the pattern performance of a directive antenna is discussed. The free-space azimuth monopulse antenna is characterized by its sum and difference mode plane wave spectra, and a computed plane wave scattering dyad is used to characterize the scattering by a metallic right circular cylinder when it is excited by the incident antenna spectra. An efficient computer algorithm has been developed to compute the far-zone scattered and total fields for the antenna/cylinder system. Extensive experimental data have been obtained, and the patterns calculated using the present analysis are in agreement with the measured data.

Omnidirectional microstrip antenna

Abstract: An electrically short, omnidirectional antenna formed with a strip conduc helically wound about the outside of a cylindrical ground plane. A layer (ideally, a very thick layer) of a nonconducting material preferably with a low dielectrical constant (i.e., er ≃1.0) separates the microstrip from the ground plane.

Stripline antenna for microwaves

Abstract: A stripline antenna for micro waves fed from one end of plural antenna arrays for easy arrangement of feeding elements, and coupled with a shielded stripline branching circuit for preventing antenna beam pattern from being disturbed by the reflected energy and for radiating the supplied energy as an effective electromagnetic wave beam.

E-Band Leaky Wave Antenna Using Dielectric Image Line with Etched Radiating Elements

Abstract: The design of a dielectric image line leaky wave antenna using etched copper disks on top of the guide as the radiating elements is described together with measurements of the properties of the antenna.

Multislot bicone antenna

Abstract: A compact multi-cone antenna is disclosed wherein quarter wavelength conesre utilized at each slot of a slotted ring antenna. The cones are selected to be quarter wavelength in order to provide an impedance transformation for better impedance matching with free space. The individual cones are chosen to have different characteristic impedances in order to provide the antenna with a sharp disc-like radiation pattern.

Multiple omnidirectional antenna

Abstract: A multiple omnidirectional antenna, utilizing individual antennae for different frequencies, and/or different polarizations, disposed along a common axis, and employing a multiple coaxial feed from one side only, in which the omnidirectional antenna which is remote from the feed side, is in the form of an axial wave-guide section, with the portion defining the walls thereof being connected to the outer conductor of the innermost coaxial feed line, and at least, in effect, defining at least one slot therein which runs transversely to the desired polarization direction of such antenna, with the inner conductor of the innermost coaxial feed line forming the exciting element therefor and projecting into the interior of said wave-guide, and/or at least one other omnidirectional antenna in the form of a coaxial line section, the walls of which are connected to the outer conductor of another coaxial feed line, and are provided with at least one slot therein which runs transversely to the desired polarization direction of said antenna, with the inner conductor of such other coaxial line passing through the interior of said coaxial line section. Combinations of horizontal, vertical and circular polarizations may be employed.

A Circularly Polarized Traveling-Wave Chain Antenna

Abstract: A novel traveling-wave antenna array with bent conductors as elements can give circularly polarized radiation. An expression for the far-field has been derived, from which the lengths and bending angle of the conductors can be calculated for circular polarization. A useful application would be printed circuit microwave antenna for different purposes. Antennas have been made and work well over reasonable large bandwidths. They can also function on their broadside frequency.

Multifrequency series-fed edge slot antenna

Abstract: A single input multifrequency antenna is disclosed which comprises a plurty of radiating elements connected in series. The device may comprise multiple conformal edge slot radiators.

Slot antenna lead connecting apparatus

Abstract: Apparatus for connecting the female connector end of a coaxial antenna lead to the members of a slot antenna includes a first connecting member having a flat base connected to one antenna member with a pair of arms at the base end farthest from the slot adapted to engage the female end of the coaxial lead and connect the outer conductor to the one antenna member. A forked extension projects from the base end nearest the slot, and the base flares outwardly in width from the arms to the forked extension to dissipate the radial electromagnetic field of the coaxial lead so it does not interfere with the slot. A second conducting member includes a conductor adapted at one end to engage the inner conductor at the female connector end of the coaxial lead and at the other end to engage the other antenna member. An insulator engages the forked extension to interlock the first and second connecting members.

Circularly polarized antenna formed of a slotted cylindrical dipole

Abstract: An antenna, particularly suitable for two-way communication between a communication satellite and an aircraft in flight, having a circular polarization response, comprising a T-matched dipole element producing a pattern polarized parallel to the axis of the aircraft fuselage, and having a slot therein which is separately excited to produce an E field orthogonally polarized with respect to the pattern of the dipole. By exciting the dipole and the slot in phase quadrature, the combined patterns provide circular polarization as is necessary for satellite communications. The shape of the antenna enclosure has a very low drag and favorable aerodynamic characteristics.

Array antenna controller

Abstract: A coherent optical processor antenna controller for controlling the patternmitted by an array antenna. Since the amplitude and phase of the antenna excitation signals are related to the far field by the Fourier transform function, a coherent optical processor, which uses lenses to take the Fourier transforms of images may be used to control the antenna excitation. The shape and direction of the pattern may be controlled by the transmittance distribution of a transparency in the processor and a null may be formed by the utilization of an additional slide.

Dipole-excited short backfire antenna with corrugated RIM

Abstract: This letter reports results of an experimental study at X-band of a dipole-excited short backfire antenna having corrugations on the main reflector rim. The results obtained show that the presence of the corrugations can lead to improved antenna gain and sidelobe levels.

Design data for coaxial Yagi array of circular loops

Abstract: Numerical data for the design of uniform coaxial Yagi arrays of circular loops are presented. For the given data the electrical dimensions of the exciter and the reflector combination are selected to be optimum for the directive gain in the forward direction.