Dual-polarized Operation Research Articles

Dual‐polarized dielectric resonator antennas

AbstractTwo feeding designs for achieving dual orthogonal linear polarization operations of dielectric resonator (DR) antennas fed by microstrip lines are demonstrated. The microstrip feedlines can be placed directly under the DR or conformal to the surface of the DR. Good dual‐polarization excitation can be obtained for the two feeding designs. Experimental results for the return loss, isolation between two feeding ports, and radiation patterns are presented and discussed. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 31: 222–223, 2001.

Degradation of availability performance in dual-polarized satellite communications systems

Dual-polarized operation of satellite communications channels allows for an efficient use of the radio spectrum. A method for evaluating the availability of Ku- and Ka-band dual-polarized digital systems is described. It is based on long-term measurements of slant-path attenuation and depolarization caused by the troposphere and of their joint occurrence. The additional degradation of dual-polarized system availability performance with respect to single polarization operation is assessed, and its dependence on major link and system parameters is highlighted. It appears that satellite links characterized by high-frequency, low elevation angle, circular polarization, and high-level modulation schemes are particularly affected by the depolarization-induced interference. In that case, doubling their capacity by dual-polarization frequency reuse reduces dramatically their availability, assuming a fixed link margin, or alternatively requires prohibitive link margins to meet a given availability objective.

Dual-frequency and dual-polarisation wideband microstripantenna

A wideband microstrip antenna with dual-frequency and dual-polarisation operation is proposed and designed to enable the transmission and reception of differently polarised wideband signals simultaneously with a single antenna system. The measured bandwidths for 15 dB return loss at dual frequencies are 9.02 and 12.4%, respectively.

Modeling of polarization-mode competition in fiber DFB lasers

A comprehensive model for steady-state analysis of polarization-mode competition in fiber distributed feedback (DFB) lasers is presented. Effects of polarization-dependent grating nonuniformities, polarization-dependent grating strength, coupling between the linear polarization states due to twist or Faraday rotation, back reflections, cross saturation from serially multiplexed lasers, as well as spatially and polarization-dependent gain hole burning are covered by the model. Regimes of single and dual polarization operation are identified for different types of polarization imperfections in the cavity. The output powers of the individual modes and the magnitudes of the hole-burning mechanisms are also calculated anti discussed.

Simultaneous dual polarisation operation of a diode pumped femtosecond fibre laser

The behaviour of a diode pumped figure-of-eight ytterbium/erbium-doped fibre laser which generates subpicosecond pulses is described. This laser is observed to mode-lock simultaneously in two orthogonal polarisation states with distinct temporal and spectral characteristics.

Dual slot-coupled microstrip antenna for dual frequency operation

A new dual slot-coupled circular microstrip antenna for dual frequency or dual polarisation operation is proposed. By optimising the placement of the two slots, high isolation between two ports is achieved. Experimentally, an isolation of more than 35dB is obtained at L-band.

Dual polarization quasi-optical beam divider and its application to a millimeter wave diplexer

A dual-polarization wire grid beam divider has been developed. This beam divider features simultaneous uniaxial dual-polarization operation, broad instantaneous coupling bandwidth, beam wave front preservation, and ease of fabrication. This paper describes a beam divider for 95 GHz, gives construction details, and presents a dual-polarization local oscillator injection diplexer as a typical example of a beam divider application.

Mode-locked dual-polarization operation of a CO<inf>2</inf>laser

An electrooptic mode-locking technique for inducing simultaneous oscillation of spacially congruent, orthogonally polarized CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser modes is described. During mode-locked dual-polarization operation the frequency separation of the output components is determined by the magnitude of an intracavity birefringence. It can therefore be adjusted to any value consistent with the gain-profile width. The sensitivity of the technique is such that for intermode frequencies between 1 and 20 MHz, a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3 \times 10^{-4}</tex> radian intracavity phase modulation suffices to produce continuous, stable dual-polarization operation. Experimental results are given that indicate the dependence of the mode-locking phenomenon on modulator drive, intermode frequency, and laser cavity tuning. These results are compared with the prediction of simple theory.