Showing papers on "Patch antenna published in 1974"

Conformal microstrip antennas and microstrip phased arrays

Abstract: A new class of antennas using microstrips to form the feed networks and radiators is presented in this communication. These antennas have four distinct advantages: 1) cost, 2) performance, 3) ease of installation, and 4) the low profile conformal design. The application of these antennas is limited to small bandwidths. Phased arrays using these techniques are also discussed.

The recovery of polarized apparent temperature distributions of flat scenes from antenna temperature measurements

Abstract: The reception theory for quasi-monochromatic partially polarized emissions is employed to describe the antenna temperature when observing a flat scene from within or above an absorbing/ emitting atmosphere When the polarization aspects of the antenna and scene are carefully observed, the resulting integral expression for the antenna temperature differs significantly from that reported for polarization invariant temperature distributions It is observed that the antenna couples to both emitted surface polarizations, and the phase character of the antenna introduces a term involving the product of the polarized and cross-polarized antenna patterns A matrix approximation of the integral expression is suggested and developed as a means for inverting polarized antenna temperature observations for the underlying partially polarized apparent temperature distributions The resulting matrix formulation is interpreted and special cases are treated By means of sample cases, the cross-coupling effect between the antenna and the emitted field polarization vectors is illustrated When the polarization aspects of the radiometer and the scene are ignored, inversions for the apparent temperature are shown to suffer appreciably even for a highly efficient antenna The sensitivity of the matrix inversion technique to errors in the measurement vector is also examined

Receiving loop antenna system

Abstract: In a receiving loop antenna especially adapted for use as a built-in antenna of a portable wireless set and of the type wherein the antenna output terminals are so tapped that power matching impedance of the wireless set may be attained, a circuit having series resonant circuit characteristics and a transmission line connected in series with the circuit and having such a length that impedance matching may be obtained, which may minimize the noise at or in the proximity of the center frequency of the frequency band of the series resonant circuit, are inserted between the antenna output terminals and the input terminals of the wireless set.

50 Ω Log-periodic monopole array with modulated-impedance microstrip feeder

Abstract: It is demonstrated theoretically and experimentally that a log-periodic monopole array with a meander-line feeder may be expected to exhibit high values of voltage standing-wave ratio. Improved match can be obtained by allowing the impedance of the feeder to go to a higher value near each monopole. A good match to 50 \Omega is achieved in this way.

Tuning structures for microstrip transmission lines

Abstract: Two embodiments are disclosed to tune microstrip transmission lines. One embodiment includes a stub strip conductor disposed on the microstrip transmission line substrate at right angles with respect to and spaced from the strip conductor of the microstrip transmission line and a tuning member at right angles to the substrate disposed over the gap between the stub strip conductor and the strip conductor. When the distance of the tuning member above the substrate is varied the shunt impedance of the microstrip transmission is varied. The other embodiment includes a tuning member threaded in a hole through the carrier of the microstrip transmission line with the metallization removed from the ground plane of the microstrip transmission line immediately above the hole. The inward and outward movement of the tuning member provides a variable series impedance for the microstrip transmission line.

Cylindrical array antenna with radial line power divider

Abstract: A cylindrical array antenna is disclosed wherein rows of antenna elements disposed about the periphery of the antenna each include a feed network coupled to a monopulse arithmetic unit through a radial line power divider and a hemispherical sector selector switching network. Monopulse "sum" and circumferential "difference" patterns are obtained by dividing a selected hemispherical sector into four adjacent antenna aperture segments. The antenna elements associated with alternate antenna aperture segments are coupled to the arithmetic unit in like polarity and the antenna elements associated with adjacent antenna aperture segments are coupled to such arithmetic unit in opposite polarity. With such arrangement cross-polarization or "null filling" effects associated with the cylindrical array antenna are reduced.

Microstrip device having mode suppressing means

Abstract: Microwave device comprising a conductive box containing a substrate which is spaced from one wall of the box and on its surface facing the wall is provided with a microstrip line; at least one coaxial terminal leading through another wall of the box is connected to the microstrip line, and at least one mode suppressing member is arranged symmetrically with respect to the axis of the microstrip line.

Windshielding structure for an antenna

Abstract: A windshielding structure for a large-diameter high-frequency dish-type antenna includes a flexible membrane extending from the edge of the antenna dish to a fixed rigid member mounted on a base plane. The membrane permits controlled movement of the antenna dish in azimuth and elevation, but minimizes the effect of wind approaching the dish from the front direction (head-on wind) by preventing the wind from interacting with the antenna dish edge to cause Von Karman vortices and associated mechanical oscillations of the antenna. The enclosure formed behind the antenna dish by the membrane, the antenna dish, the fixed rigid member and the base plane can be used for protection of equipment and personnel. The fixed rigid member may have a lip protruding from its surface to divert from the dish and membrane, wind approaching the antenna dish from other directions.

Wide band radio-frequency phase sensor

Abstract: A phase sensing device, indicating RF transmitter antenna resonance with a high degree of accuracy, for use with tuneable antennae operating in a frequency range of 2 - 30 MHz. The device operates by sampling a time varying (RF) voltage and current appearing at the antenna feed point. A sample of the voltage between the antenna terminal and ground is vectorially combined in two ways with the voltages proportional to the antenna input current. In the first combination, the voltage is derived from the current and leads the current by 90*, while in the second combination, it lags the current by 90*. The resultant RF voltages are rectified independently, and the two independent DC voltages obtained are combined or added with opposite polarity. The difference of the two DC voltages is then the output signal of the sensor and since proportional to the phase difference of voltage and current in the antenna is indicative of the resonant condition of a tuneable antenna. The sensing error signal of the present device may then be connected to amplifiers and a servo motor coupled to a tuning reactor attached to the antenna. The device includes a transformer, center tapped to ground substantially eliminating stray capacitive effects, while the overall circuit requires no balancing adjustment because of its inherent symmetry.

Microstrip antenna study for Pioneer Saturn/Uranus atmosphere entry probe

Abstract: The design parameters of a microstrip antenna were studied to determine its performance characteristics as affected by an atmospheric entry probe environment. The technical literature was reviewed to identify the known design and performance characteristics. These data were used to evaluate the expected effects of mission environments on the microstrip antenna design proposed for the Saturn/Uranus Atmospheric Entry Probe (SAEP). Radiation patterns and VSWR measurements were made to evaluate the performance in the SAEP thermal environment. Results of the literature search and pattern tests confirm that the microstrip antenna is a good choice as a transmitting antenna on the SAEP. The microstrip antenna is efficient, compact, and well suited to a space environment. The pattern can be controlled with a minimum beamwidth of 60 degrees (air substrate; e.g., honeycomb structure) and a maximum on the order of 100 degrees with higher dielectric constant substrates. The power handling capacity is good and can be improved by covering the antenna with a dielectric cover.