Twin Dipole Research Articles

Development of a Short Model of the Superconducting Separation Dipoles D2 for the High Luminosity Upgrade of LHC

The luminosity upgrade of the Large Hadron Collider requires that the new separation/recombination dipoles D2 deliver a field integral of 35 Tm. A design has been developed of a twin dipole generating a magnetic field as high as 4.5 T in apertures of 105-mm and 7.78-m magnetic length. The magnetic field direction is identical in both apertures causing not negligible magnetic cross talk, which could be highly detrimental for the field quality. In order to minimize the cross talk effects a design based on asymmetric coils has been developed in the past years. Recently, the design has achieved a level of maturity allowing the starting of a second phase of development involving the construction of a short model preliminary to prototyping activities. The short model (1.6-m long) has been designed in all aspects and it is presently under construction in industry. The contribution is focused on the design of the short model with emphasis on the mechanical aspects, which includes a novel approach to the integration of coils in the mechanical structure through the use of Al-alloy sleeves.

A Novel Dipole Antenna Design With an Over 100% Operational Bandwidth

A novel design of a dipole antenna with ultrawideband characteristics is presented, which uses an additional shorter dipole as a matching element whose imaginary part (or susceptance) of input admittance compensates for that of the principal dipole in the frequency band of operation. Since both dipole elements efficiently radiate energy, the proposed twin-dipole antenna exhibits a higher efficiency compared to a conventional design. The measurement results have revealed that the twin-dipole is able to achieve a bandwidth of 131% ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> 11 <; -10 dB) from 1.6 GHz up to 7.7 GHz, with good radiation performance and more than 75% radiation efficiency.

A New Millimeter-Wave Printed Dipole Phased Array Antenna Using Microstrip-Fed Coplanar Stripline Tee Junctions

A new millimeter-wave printed twin dipole phased array antenna is developed at Ka band using a new microstrip-fed CPS tee junction, which does not require any bonding wires, air bridges, or via holes. The phased array used a piezoelectric transducer (PET) controlled tunable multitransmission line phase shifter to accomplish a progressive phase shift. A progressive phase shift of 88.8/spl deg/ is achieved with the 5 mm of perturber length when the PET has full deflection. Measured return loss of the twin dipole antenna is better than 10 dB from 29.5 to 30.35 GHz. Measured return loss of better than 15 dB is achieved from 30 to 31.5 GHz for a 1/spl times/8 phased array. The phased array antenna has a measured antenna gain of 14.4 dBi with 42/spl deg/ beam scanning and has more than 11 dB side lobe suppression across the scan.

Photoconductive twin dipole antennas for THz transceiver

A THz transceiver using twin photoconductive dipole antennas fabricated on the same substrate chip has been demonstrated. With reduced photoconductive noise compared to that of a single photoconductive transceiver, signal-to-noise operation as good as that of a conventional separate emitter-receiver system was achieved. An interference effect due to the adjacent antennas was also observed.

10 GHz GaAs monolithic twin‐dipole antenna FET mixer

AbstractThe first fully monolithic X‐band twin‐dipole antenna mixer consisting of a uniplanar twin‐dipole antenna and a GaAs MESFET single‐gate mixer on the same GaAs substrate fabricated by monolithic microwave integrated‐circuit technology (MMIC) is reported. The total chip size is 5×5 mm2. This circuit received an RF signal of 10 GHz, and down‐converted it to an IF signal of 1 GHz with a conversion loss of 22 dB. The experimental results demonstrate that this topology has potential applications for future low‐cost millimeter‐wave receivers for smart munitions seekers and automotive‐collision‐avoidance radars. © 2001 John Wiley &amp; Sons, Inc. Microwave Opt Technol Lett 30: 436–438, 2001.

Model-based characterization of CPS-fed printed dipole for innovative design of uniplanar integrated antenna

A printed dipole radiator fed by coplanar stripline (CPS) is modeled by using a full-wave method of moments (MoM), and its input impedance is accurately extracted (de-embedded) by applying a so-called "short-open calibration" (SOC) scheme. An offset CPS-fed dipole radiator is studied, and its pertinent results show a significant reduction of its input impedance with enlarging the offset. Two new uniplanar integrated antennas in the form of single and twin dipole radiators are designed jointly with an innovative hybrid FGCPW and CPS feeder, and predicted characteristics are well confirmed by our measurements.

60 GHz sources using optically driven heterojunction bipolar transistors

Millimeter wave sources at 60 GHz have been demonstrated using optically driven heterojunction bipolar transistors configured as photodetectors. Two techniques were used to optically generate the millimeter waves; the mixing of two cw lasers and the mode locking of a semiconductor laser. The millimeter wave power generated from these two configurations was radiated into free space using integrated planar twin-dipole antennas and heterodyne detected with signal-to-noise ratios ≳40 dB. As part of these experiments, the dc optical gains and quantum efficiencies of the heterojunction bipolar transistor photodetectors were determined.

Millimeter-wave imaging using FET detectors integrated with printed circuit antennas

The application of field effect transistor (FET) detectors integrated with planar twin dipole microstrip antennas to millimeter-wave imaging has been demonstrated. Circuits were configured as practical heterodyne mixers, as elements in a 2×3 element planar focal plane array for imaging, and as receivers in frequency modulated (FM) radars for three-dimensional imaging, at 63 GHz. These experiments show that quasioptical circuits, using conventional present-day FETs and simple printed circuit construction, can be applied usefully in the millimeter-wave region.

Printed circuit antennas with integrated FET detectors for millimeter-wave quasi optics

Planar twin dipole microstrip antennas with integrated FET detectors which provide antenna patterns suitable for millimeter-wave quasioptical applications are discussed. The circuits are suitable for use as individual elements of an imaging array. A 63-GHz heterodyne mixer using such a circuit produced a system noise temperature of 7900 K.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>