|Title of Invention||
"MULTICHANNEL ROTATABLE JOINT (VARIANTS)"
|Abstract||The invention relates to the UHF radio engineering and can be used for UHF signals transmission from the fixed to the rotatable part of a multichannel coaxial transmission line. The technical result of the invention is the simplification of the structure, reduction of dimensions and extension of operating frequency band. The multichannel rotatable joint (Fig. 1) comprises concentrically arranged coaxial line (2, 3) sections with quarter-wave short-circuited insulators and matching transitions at the ends which are movably joined by a system of quarter-wave choke gaps (17). The short-circuited insulators (19, 20) are based on a plane parallel radial line, and matching transitions are made on a stripe line (21, 22) in the form of two parallel branches (24), comprising multistage impedance transformers (25, 26, 27). The embodiment of a multichannel rotatable joint, in which the length of the coaxial line (2, 3) sections of the multichannel rotatable joint fixed and rotatable parts is selected equal to the odd number of quarter-wave lengths, is also disclosed.|
|Full Text||MULTICHANNEL ROTATABLE JOINT (VARIANTS)
DESCRIPTION OF THE INVENTION Field of the invention
The invention relates to UHF radio engineering and can be used for transmitting UHF signals from the fixed to the rotatable part of a multichannel coaxial transmission line, for example, in multifunctional volume radar.
Background of the invention
In the known construction of multichannel rotatable joint (patent of Japan: N° 62-5521, 1987; tfa 62-39841, 1987 and N° 62-39842, 1987) short concentric sections (enveloping each other) of coaxial lines with quarter wave short-circuited loops on the ends, performing functions of quarter wave insulators, are used ("Lines for transmission of centimeter waves", translation from English language, edited by G.A. Remez, Publishing house "Soviet Radio", M.I951, p.p. 172-184) Rotation of the movable part of the joint relatively to the fixed part is provided by the system of the quarter wave choke gaps made in conductors of the coaxial lines and by bearings. Matching of low impedance coaxial lines with standard coaxial connectors oriented perpendicularly to the axis of rotation is achieved by using of stepped and cone-shaped transitions. Essential drawbacks of the know construction of multichannel rotatable joints are great length owing to presence of the quarter wave short-circuited insulators made on the base of coaxial line and insufficient operating frequency band owing to great drop of wave impedance and cross-section of coaxial lines as compared with standard meanings.
Summary of the invention
The aim of the said invention is simplification of the construction, reduction of external dimensions and extending of operating frequency band. Technical result is achieved thanks to the fact that quarter wave short circuited insulators are made on the base of the plane parallel radial line, lengths of coaxial line sections of the fixed and rotatable parts of the multichannel rotatable joint were selected equal to the odd number of quarter waves and matching transitions are made on the base of a stripe line in a form of two parallel branches comprising multistage impedance transformers and located in circumference manner.
Brief description of the drawings
Construction of a three channel rotatable joint in longitudinal section is shown in Fig.l, and in Fig.2 - in lateral section coinciding with the plane of the matching transition from coaxial line to coaxial connector.
Description of the preferred embodiment
In construction the three channel rotatable joint present a system of three enveloping each other central coaxial line 1, middle coaxial line 2 and outer coaxial line 3 with the common axis of symmetry 4, around which the rotation is carried out (further axis of rotation).
Input coaxial connector 5 and output coaxial connector 6 of the central coaxial line 1 are located on the axis of rotation, input coaxial connector 7 and output coaxial connector 8 of the middle coaxial line 2 and input coaxial connector 10 of the outer coaxial line 3 are located on the outer cylindrical
surface of bodies 11,12,13 and 14 correspondingly which are used for location of matching transition. Rotation of the upper part 15 relatively to the fixed lower part 16 is provided, as in prototype, at the expense of the system of quarter-wave choke gaps 17 in conductors of the coaxial lines and bearings 18.
High frequency resistant insulation of central conductors from outer conductors of coaxial lines 2 and 3 is provided by short-circuited radial gaps 19,20, radius of which is approximately equal to the quarter of the wave length. The choice of the height h, defining input resistance of the plane parallel radial line, influences the level of matching and broadbandness of the device because the plane parallel radial line in the frequency band (Theory of lines for transmission of UHF, translation from English language, edited by A.I. Shpuintov, Publishing house "Soviet Radio", M.I951, p.p. 16-40) conducts itself as a short-circuited section of a quarter wave coaxial line, i.e. as a parallel resonance contour.
The lengths L2 and L3 of the coaxial lines 2 and 3, i.e. distances between the points of contours' connections should be choosed equal to the odd number of quarter wave length because it gives mutual compensation of reflection and increases broadbandness of the device.
Wave impedance p of a coaxial line, as it is known (A.A. Foldshtane and others. "Reference book on elements of waveguide technique", Publishing house "Soviet Radio", M.I967, p.p. 92-94) is defined by correlation: p=138 Ig D/d ohm, where D and d are diameters of outer and inner conductors of the coaxial line. Wave impedance of standard coaxial connectors is equal to 50 ohm. Dimensions of conductors D and d for central coaxial line 1 it is
advisably to choose of a kind that wave impedance of the line corresponds to standard, i.e. 50 ohm.
During selection of dimensions for conductors D and d of coaxial lines 2 and 3 it is necessary to follow constructional considerations, as a result their wave impedance is much lower than standard, of the order of 10 ohm. Therefore for their matching with standard coaxial connectors it is advisable to use matching transitions, made on the base of the stripe lines 21 and 22 containing body of circular form 23 and central conductor in a form of two parallel branches 24 containing three-stage impedance transformers 25,26,27. Such a form of a matching transition decreases twofold cross-section of a conductor, provides symmetry of connection with central conductor of coaxial line and in optimal manner blend with the construction of the device. There are dielectric insertions 28 for fixation the position of stripe lines' conductors. The declared construction of multichannel rotatable joint is characterized by technological effectiveness in production of components and in assembling. Technology of production of some components and assemblies is seen in given drawings and assembling is carried out with the help of screws 29 and 30.
A possibility of practical realization of the proposed construction of the multichannel rotatable joint was verified experimentally. In operating frequency band from 1,0 to 1,6 GHz (A/p=±23%) it was received: VSWR (Voltage Standing Wave Ratio) of all three channels - not more that 1,5; losses - (0,2-0,5)dB; decouplings between neighbouring channels - not less that 20 dB; between edge channels - not less that 40 dB; modulation factor of parameters during rotation - not more 1%. Dimensions of the device: - 0 180x180 mm; weight - 7,5 kg.
1. Multichannel rotatable joint comprising concentrically arranged
sections of coaxial lines (2, 3) with quarter-wave short-circuited
insulators and matching transitions on the ends movably joined by a
system of quarter- wave choke gaps (17) characterized in that the
quarter-wave short-circuit insulators (19, 20) are made on the base of
a plane parallel radial line and matching transitions are made in a
form of two parallel branches of a stripe line (21, 22) comprising
multistage impedance transformers (25, 26, 27).
2. The Multichannel rotatable joint as claimed in claim 1, having three
3. The Multichannel rotatable joint as claimed in claim 1, wherein the
lengths of coaxial line (2, 3) sections are selected equal to the odd
number of quarter-wave lengths.
4. The Multichannel rotatable joint as claimed in claim 3, having three
|Indian Patent Application Number||4684/DELNP/2006|
|PG Journal Number||28/2009|
|Date of Filing||14-Aug-2006|
|Name of Patentee||FEDERAL STATE UNITARY ENTERPRISE "STATE MOSCOW PLANT "SALYUT"|
|Applicant Address||6 PLEKHANOV STR., MOSCOW 111123, RUSSIA|
|PCT International Classification Number||H01P 1/00|
|PCT International Application Number||PCT/RU2005/000190|
|PCT International Filing date||2005-04-14|