Parallel Rectangular Waveguides Research Articles

Design of a Four-Branch Optical Power Splitter Based on Gallium-Nitride Using Rectangular Waveguide Coupling for Telecommunication Links

This paper reports design of a simple four-branch optical power splitter using five parallel rectangular waveguides coupling in a gallium-nitride (GaN) semiconductor/sapphire for telecommunication links. The optimisation was conducted using the 3D FD-BPM method for long wavelength optical communication. The result shows that, at propagation length of 925 μm, the optical power input was successfully split into four uniform output beams, each with 24% of total input power. It is also shown that the relative output power distribution is almost stable through the C-band range. At the operating wavelength of 1.55 μm, the proposed power splitter has an excess loss lower than 0.2 dB. This study demonstrates the opportunity to develop optical interconnections from UV-Visible to near IR wavelengths.

An Optical Power Divider Based on Mode Coupling Using GaN/Al2O3 for Underwater Communication †

This paper details the design of a 1 × 8 optical power divider, using a gallium nitride (GaN) semiconductor on sapphire, which can be applied to underwater optical wireless communication. The design consists of nine parallel rectangular waveguides which are based on mode coupling phenomena. Analysis of the design was performed using the beam propagation method (BPM). The optimization was conducted using the 3D finite difference (FD)-BPM method with an optical signal input at the wavelength required for maritime application of λ = 0.45 µm. The signal was injected into the central waveguide. The results showed that at a propagation length of 1480 µm the optical power is divided into eight output beams with an excess loss of 0.46 dB and imbalance of 0.51 dB. The proposed design can be further developed and applied in future underwater communication technology.

A large-volume microwave plasma source based on parallel rectangular waveguides at low pressures

A large-volume microwave plasma with good stability, uniformity and high density is directly generated and sustained. A microwave cavity is assembled by upper and lower metal plates and two adjacently parallel rectangular waveguides with axial slots regularly positioned on their inner wide side. Microwave energy is coupled into the plasma chamber shaped by quartz glass to enclose the space of working gas at low pressures. The geometrical properties of the source and the existing modes of the electric field are determined and optimized by a numerical simulation without a plasma. The calculated field patterns are in agreement with the observed experimental results. Argon, helium, nitrogen and air are used to produce a plasma for pressures ranging from 1000 to 2000 Pa and microwave powers above 800 W. The electron density is measured with a Mach–Zehnder interferometer to be on the order of 1014 cm−3 and the electron temperature is obtained using atomic emission spectrometry to be in the range 2222–2264 K at a pressure of 2000 Pa at different microwave powers. It can be seen from the interferograms at different microwave powers that the distribution of the plasma electron density is stable and uniform.

Improving the characteristics of rectangular waveguide branchings by cylindrical obstacles

The scattering matrix of a transition between one or two parallel rectangular waveguides and a larger rectangular waveguide which contains two metallic or dielectric cylinders is investigated by means of the orthogonal expansion method. Mathematical programming is applied in order to improve the characteristics of the branchings. Reflection at a rectangular step discontinuity can be reduced by 30 dB using metallic or dielectric obstacles. Using Teflon cylinders, coupling of a transition can be reduced by 40 dB without debasing reflection. Physical interpretations are given with the help of field patterns.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Sensitivity of uhf wattmeters to stray harmonic signal components

quency in the range of the first, second, and third harmonic components of the signal. It is of the greatest interest to measure the relationship to frequency of the readings of a wattmeter with a complex structure of the sensing elements of its input transducer, when the computation of its sensitivity is very difficult. Therefore, we selected as objects of our investigation a waveguide multielement bolometric wattmeter [i], a wattmeter based on a multielement directional coupler with a thermistor head, and a double-element ponderomotive wattmeter [2]. The bolometric transducer consists of a rectangular waveguide section with butt-end flanges. The waveguide carries inside it perpendicularly to its wide wall 16 tungsten-wire bolometers whose length coincides with the waveguide height. The two bolometer rows are located along the waveguide axis. The uhf signal power is measured by means of the substitution method with an automatic bolometric bridge. The directional coupler of the thermistor wattmeter consists of two parallel rectangular waveguides with a common wide wall, with 16 identical holes located in two rows along the waveguide axis serving as coupling elements. The transition loss of a hole amounts, in the waveguide frequency range, to ~40 dB with a directivity exceeding 40 dB. A waveguide thermistor head is connected to the lateral arm of the directional coupler. The uhf power is also measured by means of the substitution method. The waveguide ponderomotive wattmeter consists of a rectangular waveguide with two sensing elements in the shape of rings at an angle of 45 ~ to the waveguide axis and a system for indicating the rotation angle of both ring suspensions. The ring centers are located at a distance of equal to one-fourth the working wavelength along the waveguide axis. The wattmeter scale used for indicating the suspension deflections is calibrated in watts by means of the method described in [2]. The frequency as well as the dynamic ranges of the wattmeters were chosen to be similar for comparison purposes. Thus, the working frequency ranges of the bolometric wattmeter amounts to 3.94-4.85 and 4.85-6.64 GHz, of the wattmeter with the directional coupler to 3.94-5.64 GHz, and of the ponderomotive wattmeter to 4.75-5.25 GHz. The dynamic range of the bolometric wattmeter amounts to 0.3-10 W, of the wattmeter with the directional coupler to 0.1-50 W, and of the ponderomotive wattmeter to 1-20 W. The input transducers of all the wattmeters have waveguide cross sections amounting to 48  24 mm. The frequency characteristic of each wattmeter was repeatedly measured in the working range in the course of their calibration and periodic testing, and it was found that the measured data is in good agreement with the computation results. In addition to the basic wave type H1o others arise in the waveguide with a rising frequency, therefore, their fre