A set of quasi-optical units is suggested for the design of radio measuring schemes available in the wave region 0.3...2.5 mm. The units are built on the basis of a circular hollow dielectric beamguide (HDB) of diameters 20 mm. HDB operates in the HE₁₁ mode, characterized by the plane phase front, linear polarization, and axially symmetric amplitude distribution whose maximum lies on the beamguide axis and smoothly falls as the beamguide walls is approached.

    The set includes wavemeter, attenuator, phase shifter, beam splitter, 90⁰-angled bend, termination, moving reflector, telescopic section, waveguide-to-beamguide adapter (exciter), polarization rotator, rotable joint, linear polarizer, et. al.
    The set has no analogues in Ukraine and abroad.

    Wavemeter is intended to measure wavelength. It is of the absorbing type and consists of the two parallel-plate mirrors. One is semi-transparent, the other is reflective and moving. For wavelength measurements, wavemeter is applied by the special scheme. The difference in the two readings on the wavemeter limb which correspond to the two successive negative peaks of a detector signal equals half the wavelength; the error does not exceed +5 x 10^-3.

    Measuring attenuator is designed to insert calibrated attenuation. It consists of three polarizers in the form of wire gratings. Two of them are fixed. The third is located by a rotary bush between these two in inclined position and can be turned about the waveguide axis by a mechanism associated with the attenuator scale calibrated in decibels. Insertion attenuation A is available in the range 0...25 dB with an error (0.1 + 0.03A) dB. Initial attenuation is no more than 0.5 dB and VSWR is less than 1.2.

    Adjustable phase shifter is designed to control phase shift of a SHF signal. The angled mirror moves a distance l along the bisectrix common to the corners of the angled mirror and the beam waveguide bend and causes the output signal phase shift . The reading accuracy of the angled mirror displacement is +0.005 mm. Insertion phase shift is varied from 0 to 360⁰.

    Beam splitter is intended for directional coupling of some quantity of SHF power from the primary beam waveguide to a side channel. The central element is a semi-transparent to SHF waves dielectric mirror in the form of a thin film strained in a cassette. The design provides a quick and easy change of the cassettes. A film with =2...6 and thickness (0.02...0.35), offers 1.5...20 dB of transition attenuation factor and above 30 dB of directivity factor.

    90⁰-angled bend furnishes a beam waveguide turn through 90⁰. It represents two beam waveguides connected at right angle in conjunction with a flat metal mirror which makes angles of 45⁰ with the axes of the beam waveguides.

    Termination absorbs SHF power at the beam waveguide output using a highly dissipative dielectric as absorber. For better load matching, the dielectric absorber surface is made corrugated, VSWR is 1.1.

    Moving reflector performs signal reversal with phase controlled. It represents a flat metal mirror inserted in a beam waveguide section and moving a distance 0...5 mm along the beam waveguide axis.

    Beamguide sections are used to link quasi-optical units. In-band attenuation is proportional to the square of the wavelength. In the wave band 0.5...1.7 mm, attenuation is 1...6 dB/m.

    Telescopic section is intended for a gradual change in length of the beam waveguide, which links two quasi-optical units. It consists of two beam waveguide sections, which are so jointed that they move 0...25 mm along the beam waveguide axis and can be fixed in a position.

    Waveguide-to-beamguide adapter (exciter) is designed for conversion of the HE₁₀ mode of a rectangular metal waveguide to the HE₁₁ mode of a circular hollow dielectric beamguide with no greater than 2 dB of loss.

    Polarization rotator is a unit that controls plane-of polarization rotation of a linearly polarized wave as well as phase of a circularly polarized wave. It represents a consequence of three flat metal mirrors, which are perpendicular to the plane of the beam incidence and perform in tandem. The arrangement of the mirror is such that the direction of the beam remains unchanged as it leaves rotator. The rotation of the three-mirror system about the beam waveguide axis through an angle -causes the plane of polarization to turn through an angle 2 .

    The suggested set is a complete line for basic radio measurements in the upper submillimeter and low millimeter regions.

    Some elements of the set are shown on the photo: 1-direct reading polarization attenuator; 2-direct reading polarization phase shifter; 3-attenuator-adjustable power divider; 4-polarization plane rotator; 5-wavemeter; 6-polarization converter; 7-adjustable phase shifter; 8-adjuster; 9-beam splitter; 10-cassette for polarization power divider; 11-linear polarizer; 12-90⁰-angled bend; 13- moving dihedral reflector; 14-rotable joint; 15-terminating load; 16-moving reflector; 17,18-exciters; 19-telescopic section; 20-beam waveguide section

 For more information, please contact:

 Prof. Vladimir K. Kiseliov (Volodymyr K. Kiselyov),
 Head of  the Department of Quasi-Optics,
 Usikov Institute for Radiophysics & Electronics,
 National Academy of Sciences of Ukraine (IRE NASU)
 12, Ac.Proskura St., Kharkov, 61085, Ukraine
 Phone: 380-57-7203335
 Fax: 380-57-3152105 
 E-mail: kiseliov@ire.kharkov.ua