Showing papers on "Balun published in 1985"

Coplanar microwave balun, multiplexer and mixer assemblies

Abstract: A coplanar microwave balun is disclosed in which a signal propagating along a coplanar waveguide in an unbalanced mode is launched onto another coplanar transmission line in the balanced mode. One of the ground planes of the latter transmission line itself is separated into a pair of regions which constitute the ground planes of the coplanar waveguide. These pair of regions are electrically connected, e.g., by ribbon bonds that bridge across the transmission line strip of the coplanar waveguide. The end of that transmission line strip bridges across the coplanar transmission line and acts to launch the signal thereto. The inventive balun advantageously is employed in a three port device having isolated inputs from which separate signals may be multiplexed onto a common line, and may be used in other multiplexer, mixer and modulator assemblies.

MR-apparatus having a transmission-measuring coil for high frequencies

Abstract: For increasing the sensitivity of an MR apparatus when measuring comparatively high frequencies, the radio frequency excitation measurement coil (10, 30) is divided into two individual symmetrically drivable and readable coil halves (32, 34), respectively. The mutual connection of central connections of the coil halves can be realized by means of a balun (54) but for this purpose any other symmetrical form of coupling, for example using a strip-line transformer (70) or suitably dimensioned coaxial cables (60, 62) may alternatively be used.

Apparatus and method for a portable roll-out antenna

Abstract: A portable roll-out antenna system which forms a compact, transportable assembly when not being used. The roll-out antenna system is provided with flexible antenna elements which are individually wound onto reels for storage and transportation, and rolled out for use as an efficient antenna system. Each pair of antenna elements is connected to a balun for proper connection to unbalanced connecting cables. The baluns are housed in an end-cap assembly upon which are mounted the antenna element reels when the antenna system is not being used. A power splitter allows more than one connecting cable to be electrically coupled to a remote transmitter/receiver by way of a transmission line. The power splitter is housed in a center reel assembly which is provided with a component to lockably receive part of the end-cap assembly upon which is mounted the antenna-element reels, thus holding the antenna-element reels together and forming a compact, transportable assembly.

Reference antennas for emission detection

Abstract: A reference antenna construction preferably employing a biconical antenna in combination with a balanced to unbalanced transformer or balun adapted to provide proper matching and operation over a broad frequency range. The reference antenna is used to calibrate other antennas. A ferrite sleeve is preferably used over the balun to reduce unbalanced currents flowing in the shield and to improve performance. A tool is described that allows fast and accurate construction of the balun by providing precise severing of the center conductor.

A New Slotline-Microstrip Frequency Halver

Abstract: A novel frequency-halving structure employs a matched pair of varactors in a configuration composed of both slotline and microstrip transmission-line sections. A planar 4th-order Marchand balun simultaneously provides both output matching and a balance-to-unbalance transition.

Multi-band antenna design for the HF, VHF and UHF bands

Abstract: The present invention relates to a horizontally radiating, compact multi-band antenna design of low structural height with an approximately omnidirectional characteristic, preferably for the HF (3-30 MHz), the VHF (30-300 MHz) and the UHF (300-3000 MHz) bands. The essential feature of the invention is a resonant body having a matching tube which can be used for a plurality of frequency bands. Resonance is achieved as a function of the frequency, by means of an impedance converter (BALUN) in the HF band, and by in each case one resonant plate in the VHF band and in the UHF band. The standing-wave ratio measured during optimum radiation is in each case better than 1.2.

Balanced mixer having increased signal handling capability

Abstract: A balanced mixer (12) has pairs of bidirectional diodes (23, 24), (25, 26) as switching elements that are substantially decoupled with respect to the modulating signal and are alternately and oppositely forward biased and reverse biased by the modulating signal. Since the forward biasing of the diodes in each pair in response to the modulating signal does not limit the reverse biasing of the diodes in the other pair, the reverse biasing modulating voltage far exceeds the forward biasing modulating voltage so that the diode pairs may modulate an increased level of modulated signal at reduced levels of modulating signal power consumption. To provide wide-band operation, the diode pairs are decoupled by feeding the modulating signal through separate respective bifilar-wound inductors (38, 39) or balun transformers (38', 39') exciting the diode pairs. The balanced mixer (12) is used as the first mixer in a cable television converter or in the front end of a television receiver or other UHF or microwave superheterodyne receiver (10).

An Octave-Wide Planar Microwave Frequency Doubler

Abstract: A simple frequency doubler circuit is presented, which is based on the bridge rectifier scheme with a quad of Schottky diodes and a new planar balun configuration joining a microstrip and a coplanar line. Measurement results of the frequency doubler for the output frequency in the Ku-band prove the practical usefulness of this low-cost and small-sized circuit. It is characterized by a high and nearly frequency independent conversion efficiency and a good suppression of the fundamental frequency.

Mixing circuit of television tuner

Abstract: PURPOSE:To decrease easily a spurious radiation component at an antenna terminal by using a balanced type diode modulator to a mixing circuit converting a received UHF signal into a desired intermediate frequency. CONSTITUTION:When a single balanced type diode modulator is used for the mixing circuit 5c and the balancing condition is realized completely to a balun 16 and two mixing diodes 14, 15, a local oscillating signal inputted from a local oscillating circuit 6c to a coupling line 17 is not appeared theoretically at a terminal 23 being output of the balanced modulator. It is not required to realize the complete balancing condition actually, it is sufficiently by having only to take the attenuation of a local oscillating signal valve of 20dB, and in order to realize the balancing degree like this, it is attained with almost no adjustment by applying pairing to the diodes.