Showing papers on "Balun published in 1971"

Printed circuit balun

Abstract: A printed circuit balun includes a first relatively broad conductor on a first surface of a dielectric substrate which conductor first-mentioned from an unbalanced end of the balun to a point near the opposite balanced end of the balun. On the opposite or second surface of the substrate, there is provided a second conductor that has a first relatively narrow conductor portion spaced directly opposite the first-mentioned broad conductor. The second conductor also has on the second surface a second relatively broad conductor portion parallel to the narrow portion of the second conductor. The second relatively broad conductor portion of the second conductor is coupled at a point near the unbalanced end of the balun through the substrate to the first-mentiondd broad conductor on the first surface of the substrate. The narrow conductor portion of the second conductor is joined to the broad conductor portion of the second conductor near the balanced end of the balun.

Microwave spiral antenna structure

Abstract: A microwave antenna is described including a small diameter cylindrical aluminum housing which includes a plurality of concentric cavities tuned with resonant microwave material, the remaining volume of each being essentially filled with polyurethane foam material A printed circuit spiral antenna structure overlies the cavities and is connected at its center through a microstrip balun to a coaxial conductor A conical insert forming part of the connector overlies the microstrip balun and provides mechanical support thereto, and also prevents radiation from the balun from interfering with the operation of the cavities

Balanced Transmission-Line Measurements Using Coaxial Equipment (Correspondence)

Abstract: The availability of commercial precision coaxial hybrids makes measurements on balanced two-conductor transmission lines as easy and as practical as on an unbalanced coaxial system. These hybrids, when used as a balun, transform an unbalanced coaxial system to a balanced shielded system and because of the nature of the balanced shielded system permit the measurement of the characteristics of loads connected thereto by the use of commercial coaxial test equipment. This technique has been successfully used from 600 MHz to 5 GHz, and with presently available components can be used at HF and VHF as well. The theory upon which the measurement technique is based is outlined and some results of an experimental verification included.

Hf broadband omnidirectional antenna

Abstract: An HF antenna providing high-angle skywave radiation at the lower end of the 2 MHz to 30 MHz band and low-angle skywave radiation at the upper frequencies with substantially gapless coverage in range from 0 to 1,000 miles with pattern characteristics optimized for propagation conditions. It utilizes predominantly horizontal polarization in minimizing ground losses in a log-periodic dipole array with elements lying in two orthogonal vertical planes with the apex substantially at ground level. It is an array with the phase center approximately a quarter-wavelength above ground at the lower frequencies and thereby near-vertical radiation for the short path circuits. Then as the frequency increases from 2 MHz to 6 MHz, the phase center increases from a quarter-wavelength above ground to near a halfwavelength above ground, providing lower angle radiation with omnidirectional characteristics. Antenna input impedance is from 50 ohms unbalanced coax line through an impedance transforming balun to 200 ohms balanced having VSWR with respect to the 50 ohm input line of less than 2.5 to 1. A single supporting tower occupying a near-minimum space volume is employed with phase controlled not only between orthogonal element bays but also between elements in each bay with one quarter phase spacing of elements so as to attain a desired elliptical polarization propagation characteristic.

Composite wave amplifier

Abstract: A solid state composite wave amplifier is disclosed, having a corporate fed TEM mode linear RF structure with numerous transmission lines in parallel. Negative resistance devices such as the IMPATT type diode are mounted between each transmission line to provide a plus and minus mode configuration of the RF energy with the in-phase energy being transmitted axially along the lines. Cylindrical inner and outer resistor structures selectively absorb the radiated out-of-phase energy and assure the desired propagation mode orientation. A compact hybrid structure is provided for combining large numbers of negative resistance devices with equal RF voltage, power and impedance characteristics. Input and output transitions, such as balun transformers are utilized for the two-port transmission amplifier. A single-port reflection type amplifier also incorporated the invention.

Broadband phase switches for radio-frequency and microwave interferometry

Abstract: Two wideband phase switches have been built for radio and microwave interferometry. In one, the directions of current flow in a balanced transmission line are reversed periodically. The line is coupled into the interferometer via broadband baluns. The second device switches between the E plane outputs of a magic T.