Cheby?shev quarter-wave stepped balun transformer

The design of a balun transformer from coaxial to open-wire line is presented, in which conventional quarter-wave-matching theory is used to produce a compact device with optimal Cheby?shev performance over its passband. Included in the design are the evaluation and corrections for the junction capacitances caused by stepping the outer coaxial conductor.     

Broadbanding the quarter-wave transformer using two parallel stubs

The quarter-wave transformer is broadbanded by including two parallel, open and short, eighth-wavelength stubs. A bandpass transfer function results and Butterworth or Cheby?shev designs can be achieved. Tables for practical use are presented.     

四分之一波片的制备

本文叙述一种四分之一波片的制备方法。     

Microstrip ring resonator using quarter-wave couplers

A microstrip ring resonator that uses quarter-wave coupled lines for input and output coupling is presented. The ring exhibits a double resonance due to an asymmetry in the topology of the structure. When the asymmetry is removed a single resonant peak is observed. The insertion loss of the ring is 6 dB and its quality factor is 64     

Backscattering for circular polarisation

Equations are given that express scattering for transmitting and receiving circularly polarised waves in terms of the characteristics for linear polarisation. Special cases are discussed, for which it is possible to estimate the radar cross-section for one polarisation based on data for other polarisations. Knowledge of polarisation characteristics is sometimes helpful for acquiring insight into the scattering mechanisms of complex surfaces.     

Meteor burst polarisation trials

Measurements over an 850 km path show that radio waves reflected by ionised meteor trails are typically received with the same polarisation as they were transmitted. Furthermore, a vertically polarised wave seems to suffer a 3?4 dB larger loss than a horizontally polarised one.     

All-fibre wideband polarisation beam-combiner

An all-fibre polarisation beam-combiner with more than 200 nm spectral width for -15 dB extinction ratio is demonstrated. The design is based on a narrowband polarisation beam-combiner coupler in association with a WDM coupler in a Mach-Zehnder interferometer structure.     

Monomode fibre polarisation scrambler

A technique for the pseudodepolarisation of a long-coherence-length source is described, which is based on a simple polarisation modulation scheme. Using a length of high-birefringence fibre wound on to a piezoelectric transducer, a simple all-fibre polarisation scrambler can be constructed.     

Synthesis of octave-band quarter-wave coupled semi-trackingstripline junction circulators

The complex gyrator circuit of stripline circulators using tracking junctions which satisfy the physical and magnetic variables of the Wu and Rosenbaum boundary conditions, is a nearly frequency independent octave-band resistive network. Such a junction may exhibit two minimas in its reflection coefficient when matched by a two section impedance transformer. However, a third minima may be realised by utilizing a complex rather than a real gyrator circuit. This paper summarises this class of semi-tracking solution in a simple way as a preamble to the design of a degree-3 quarter wave coupled circulator. The overall frequency behaviour of this class of junction has been separately evaluated by combining the electromagnetic and network problems (in conjunction with a two step impedance matching network)     

Practical design of side-coupled quarter-wave shifteddistributed-Bragg resonant filters

This paper presents equations that the together the spectral response, physical dimensions, and optical properties of side-coupled quarter-wave shifted distributed-Bragg resonant filters. Four constraints on the available design space are presented to show that side-coupled resonant filters, as designed herein, must, remain narrow-band to achieve acceptable performance. The global design space and the available design subspace for the InGaAsP/InP and Ge-doped SiO ₂ material systems are presented, as well as a discussion of modifications that can be made to improve the scope of possible filter designs     

All-single-mode-fibre interferometric polarisation beam splitter

A novel all-fibre polarisation beam splitter based on an all-fibre Mach-Zehnder interferometer (MZI) is reported. The device symmetrically separates orthogonally polarised components of an incoming optical signal with isolations between these components of greater than 17 dB at each output     

Three orthogonal polarisation DRA-monopole ensemble

A dual feed HE/sub 11/spl delta// mode dielectric resonator antenna (DRA) loaded monopole antenna ensemble is described. The two antennas were unaffected by co-location, having coupling less than -25 dB at 2.33 GHz, making the ensemble capable of radiating all three orthogonal linear polarisations. The dielectric resonator antenna had an input impedance bandwidth of 1.9%, while the monopole gave 56%. This small volume ensemble antenna is suitable for mobile communications terminals.     

Lithium niobate waveguide polarisation convertor

A wavelength-insensitive, integrated-optic lithium niobate device capable of arbitrary polarisation transformations is described. Detailed investigation of the experimental performance shows excellent agreement with the theoretically predicted behaviour     

Rugged all-fibre endless polarisation controller

A polarisation controller comprising four lengths of PM fibre wound onto piezoelectric cylinders has been produced. It is mechanically rugged, has an insertion loss of 1.5 dB, and is capable of endless control between two arbitrary time-varying states of polarisation. Polarisation control has been successfully demonstrated for the first time in a coherent optical transmission system over installed fibre     

一种测量1/4波片相位延迟量的新方法

提出了一种通过软件计算输出椭圆偏振光矢的长短轴来测量1/4波片相位延迟量的新方法,其测量光路简单易行,仅由光源、起偏器、待测1/4波片、检偏器和光功率计组成,测量结果通过Mathcad进行分析运算,得到波片的相位延迟量。文中详细论证了新方法的原理过程,给出了应用实例与误差分析,结果表明:新方法的绝对测量误差小于0.26。该方法的主要优点是光学器件少,操作简单,易于实现,引入误差小,测量精度高。