WO2008114281A2 - Dual channel rotary joint for space borne scanning antenna - Google Patents
Dual channel rotary joint for space borne scanning antenna Download PDFInfo
- Publication number
- WO2008114281A2 WO2008114281A2 PCT/IN2008/000161 IN2008000161W WO2008114281A2 WO 2008114281 A2 WO2008114281 A2 WO 2008114281A2 IN 2008000161 W IN2008000161 W IN 2008000161W WO 2008114281 A2 WO2008114281 A2 WO 2008114281A2
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- WIPO (PCT)
- Prior art keywords
- waveguide
- rotary joint
- microwaves
- channel
- rectangular
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/06—Movable joints, e.g. rotating joints
- H01P1/062—Movable joints, e.g. rotating joints the relative movement being a rotation
- H01P1/066—Movable joints, e.g. rotating joints the relative movement being a rotation with an unlimited angle of rotation
- H01P1/067—Movable joints, e.g. rotating joints the relative movement being a rotation with an unlimited angle of rotation the energy being transmitted in only one line located on the axis of rotation
Definitions
- the present invention related to a dual-channel rotary joint for space- borne scanning antennas.
- the invention relates more particularly to a dual-channel rotary joint of relatively simple design, reduced weight and dimensions, low-cost construction, and suitable for scanning operations in the Ku-band i.e. 13.515GHz + 25 MHz frequency, in which the mode transducers of compact and rugged construction have been incorporated to ensure reliable and durable performance of the joint in converting the microwaves of TE 10 mode in rectangular waveguides into microwaves of rotationally symmetric orthogonal modes TM 01 and TE 01 in a circular waveguide at the signal input ends, and reconverting the microwaves of rotationally symmetric orthogonal modes TM 01 and TEOl in a circular waveguide into microwaves of TE 10 mode in rectangular waveguides at the signal output ends.
- the rotationally symmetric orthogonal modes TM 01 and TEOl of microwaves excited in the circular waveguides are higher modes.
- the dominant mode having the lowest cut off frequency is TE 11.
- microwaves of higher mode TM 01 have been excited in circular waveguide by using an axial probe from microwaves of mode TE 10 in rectangular waveguide of one channel of input signal and microwaves of higher mode TEO 1 in circular waveguide have been excited by using two axial slots in the wall of the circular waveguide from the microwaves of TElO mode of rectangular waveguide of the other channel of input signal.
- Microwaves of dominant mode TEIl in the circular waveguide have not been excited from microwaves of mode TElO in rectangular waveguides of the two channels of input signal for the reasons, such as, (a) the higher mode TM 01 has a relatively high power carrying capacity combined with circular symmetry with the other higher mode TE 01, (b) the return loss as well as the insertion loss of signal energy at the rotary joint, and variation in insertion loss of signal energy with rotation of circular waveguide are lowered by exciting the higher modes TM 01 and TE 01, (C) isolation between the signals of the two input channels is improved by exciting TM 01 mode for one channel and TE 01 mode for the other channel; and (d) there is an appreciable cross-talk between the signals of the two input channel, if the dominant mode TE 11 is excited in the circular waveguide from TE 10 mode of both the input channels.
- WO 2005/051 604 A7 a method and assembly device for producing a rotary joint between a drive element and a flange is described.
- a bolt of the drive element is driven into a nut of the flange until the bolt is drawn into a bore in the flange.
- a rotary joint comprising an assembly of non- contacting overlapping sleeves which are electrically coupled to one another at microwave frequencies and rotatable relatively about an axis.
- a pair each of inner and outer tubular conductors are disposed co-axially to form waveguide cavities, one end of which is connected to the said sleeves and the other end is fed with input signals excited in selected modes.
- the conventional dual-or multi-channel rotary joints realized in coaxial configuration have the main limitation in that these are applicable for propagating microwaves of lower frequency bands only, such as L-, C- and X- bands.
- the realisation of such joints for propagating microwaves of Ku-and still higher frequency bands is difficult, because of the reduced gap of lmm or so required between the inner and outer conductors of the co-axial configuration, with consequent reduction of the power handling capacity of such joints.
- the return loss and insertion loss of signal energy propagated in conventional rotary points is relatively high together appreciable variation in the insertion loss of signal energy with rotation of joints.
- the isolation between signals of channels is also relatively low.
- the rotary joint of the present invention has been realized by eliminating the inner conductor of the coaxial configuration, that is, by using a circular/cylindrical waveguide in which microwaves of higher mode TM 01 are excited using a co-axial probe, integrally constructed with a metallic post or a multi-section ridge of stepped structure provided in a rectangular waveguide through which microwaves of mode TE 10 of one channel of input signal are fed into the circular waveguide.
- Microwaves of higher mode TE 01 are excited in the cicular waveguide by using axial slots in the wall thereof from microwaves of mode TElO in the rectangular waveguide of the other channel of input signal.
- the object of the present invention is to provide a dual-channel rotary joint of relatively simple design, rugged and low-cost construction, light weight and reduced dimensions, suitable for operation in the Ku-band of microwaves in space-borne scanning antennas.
- the other object is to provide a rotary joint in which the return and insertion loss of signal energy is lowered, the variation in insertion of signal energy with rotation of the joint is reduced, and the isolation between the signals propagated through the joint is increased.
- Another object is to provide a rotary joint of reliable and durable performance under low pressure environment of the upper space.
- the dual-channel rotary joint comprises two circular waveguides, called upper cylindrical waveguide and lower cylindrical waveguide, rotatably engaged at the adjoining overlapping ends thereof in a ball bearing.
- an end cover with a co-axial probe, and rectangular waveguides, and axial slots on the wall thereof are provided.
- the input signals of two channels are fed at the top end of the upper cylindrical waveguide through two rectangular waveguides.
- the output signals are delivered at the bottom end and bottom wall of the lower cylindrical waveguide through two channels of rectangular waveguides.
- the probe introduced in the upper cylindrical waveguide acts as the transducer for exciting microwaves of mode TM 01 from the microwaves of mode TElO supplied through the rectangular waveguide of one channel of input signal and the probe introduced in the lower cylindrical waveguide acts as the transducer for converting the microwave of mode TM 01 into microwaves of mode TE 10 delivered into rectangular waveguide of one channel of output signal.
- Microwaves of mode TE 10 fed into the upper cylindrical waveguide through the rectangular waveguide of the other channel of input signal are converted into microwaves of mode TEOl in circular waveguide by two axial slots provided in the wall of the upper cylindrical waveguide.
- Microwaves of mode TEOl are converted into microwaves of mode TElO by two axial slots provided in the wall of the lower cylindrical waveguide and delivered into rectangular waveguide of the other channel of output signal.
- the probes introduced into the upper and lower cylindrical waveguides are each attached to a multi-section stepped ridge acting as impedance matching transformer and provided as an integral part of a rectangular waveguide, mechanically connected one each to the upper and the lower cylindrical waveguides.
- the present invention provides a dual-channel rotary joint for space-borne scanning antennas, characterised in that the rotary joint comprises an upper cylindrical waveguide attached to rectangular waveguide with a 90° - bend for one channel of input signal and to a rectangular waveguide for the other channel of input signal, and a lower cylindrical waveguide attached to rectangular waveguides for one channel of output signal and to rectangular waveguides for the other channel of output signal, the top part of the said lower cylindrical waveguide being rotatably engaged with the bottom part of the said upper cylindrical waveguide in a ball bearing, an axial probe and two axial slots being provided in the said upper cylindrical waveguide for exciting respectively microwaves of modes TM 01 and TEOl from microwaves of mode TElO fed through rectangular wave guides for both channels of input signal, and an axial probe and two axial slots being provided in the said lower cylindrical waveguide for converting respectively microwaves of modes TMOl and TEOl into microwaves of TElO delivered through rectangular waveguides of both channels of output signal.
- Figure 1 is a three-dimensional CAD view of the invented joint
- Figure 2(a) is a three-dimensional CAD view of the upper stationary part of the invented j oint;
- Figure 2(b) is a three-dimensional CAD view of the lower rotatable part of the invented joint
- Figure 3 (a) shows the two-dimensional sketch
- Figure 3(c) shows three-dimensional sketch of the invented joint
- Figure 4 is an exploded view of the upper stationary part of the invented joint.
- Figure 5 is an exploded view of the lower rotatable part of the invented joint.
- the upper stationary part of the invented joint comprises two signal input ends (5), rectangular waveguide (22) with 90°- bend (1) as channel of one input signal, rectangular waveguide (23) as channel of other input signal, upper cylindrical waveguide (4) with end cover (2) and interface mounting lugs (3); and the lower rotatory part comprises the lower cylindrical waveguide (6) with end cover (7), side tapered rectangular waveguide (8), side cross rectangular waveguide (10) and side tapered rectangular waveguide (12) forming one channel of output signal and bottom- middle top rectangular wavegide (9), bottom straight rectangular waveguide
- pressurized flanges (14) are attached one each at the feed ends of rectangular waveguides (22, 23) and output end of rectangular waveguides (11, 12) for interfacing the signal input sources and output networks .
- the inner surface of a ball bearing is fitted on the outer surface (15) of the upper cylindrical waveguide (4), and the outer surface of the ball bearing is fitted on the inner surface (16) of the lower cylindrical waveguide (6).
- Upper cylindrical waveguide (4) is provided with two axial slots (25,
- the probe (24) is axially introduced into upper cylindrical waveguide (4) to excite therein microwaves of mode TMOl from microwaves of mode TElO fed thereinto through rectangular waveguide (22) having 90°- bend (1).
- the probe (24 ; ) is introduced axially into the lower cylindrical waveguide (6) to convert microwaves of mode TMOl into microwaves of mode TElO delivered through rectangular waveguides (9 and 11).
- Axial slots (27, 28) are provided in the wall of lower cylindrical waveguide (6) to convert microwaves of mode TEOl into microwaves of mode
- TElO delivered through rectangular waveguides (8, 10 and 12). Slots (27, 28) are located on the wall of lower cylindrical waveguide where the phase of the electric field is the same.
- Microwaves of mode TM 01 having magnetic lines of force in planes perpendicular to the axis of cylindrical waveguides are excited by using axial probes and microwaves of mode TEOl having electric lines of force in planes perpendicular to the axis of cylindrical waveguides are excited by using axial slots. ⁇ •
- Multi-section stepped ridges (19 and 19 ; ) are integrally attached to inner surface of rectangular waveguides (22, 9) and also to probes (24,24 ; ) respectively and are provided for matching the impendance at the output and input ends of the probes and also to make the joint compact and mechanically rugged to ensure its reliable and durable performance in space-borne scanning antennas, with reduced return and insertion loss, and variation in insertion loss with rotation of joint, of the signal energy propagated therethrough, as well as to increase the power handling capacity thereof.
- the rectangular waveguides used in the invented joint are of type WR62 and provided with pressurized interfacing flanges (14) shown in Figs. 2(a) and 2(b) to make the structure of the rotary joint mechanically rigid and to reduce leakage of signal energy at the interfaces thereof.
- the lower cylindrical waveguide (6) with the associated rectangular waveguides (8, 9, 10, 11, 12) is rotatable with respect to the upper cylindrical waveguide (4) over an angle of 360° (WoW).
- a non-contacting type RF choke joint (not-shown) is provided adjacent the overlapping surfaces of the upper and lower cylindrical waveguides (4, 6) to reduce leakage of microwave signals through the gap at the rotary joint.
- the upper cylindrical waveguide (4) is provided with a ring (18) and a lock ring ( 17) at the bottom end thereof.
- the ball bearing (20) with ring (21) is provided in the gap between the overlapping surfaces of the upper and lower cylindrical waveguides to engage the lower cylindrical wavegide (6) rotatably with the upper cylindrical waveguide (4) (shown in Fig. 5).
- the ball bearing used in the rotary joint is of angular contact type having inner diameter 40 mm and outer diameter 52 mm.
- the rotary joint is of height 225 mm, maximum diameter 90mm and weight 600 gm, and is capable of handling microwave peak power 110 watt and average power 30 watt.
- the specified values, simulated results and measured results (obtained on laboratory model of the invented rotary joint) on the operational parameter of the invented rotary joint are presented in Table I, from which it is noted :-
- the joint is operable at the frequency range of 13.515 GHz + 25 MHz;
- the invented rotary joint is suitable more specifically for scanning a pencil beam scatterometer antenna for space-borne remote sensing application in the retrieval of ocean wind vector.
- Table -I The Specified Values. Simulated Results and Measured Results (obtained on the laboratory model) on the Operational Parameters of the Invented Dual Channel Rotary Joint
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- Waveguide Connection Structure (AREA)
Abstract
The rotary joint comprises an upper cylindrical waveguide attached to rectangular waveguide having 90°- bend for one channel of input signal and to rectangular waveguide for the other channel of input signal, and a lower cylindrical waveguide attached to rectangular waveguides for one channel of output signal and to rectangular waveguides for the other channel of output signal, the top part of the said lower cylindrical waveguide being rotatably engaged with the bottom part of the said upper cylindrical waveguide in a ball bearing, and axial probe and two axial slots being provided in the said upper cylindrical waveguide for exciting respectively microwaves of modes TM01 and TE01 from microwaves of mode TE10 fed through rectangular waveguides, and an axial probe and two axial slots being provided in the said lower cylindrical wave guide for converting respectively microwaves of modes TM01 and TE01 into microwaves of mode TE10 delivered through rectangular waveguides.
Description
The present invention related to a dual-channel rotary joint for space- borne scanning antennas.
The invention relates more particularly to a dual-channel rotary joint of relatively simple design, reduced weight and dimensions, low-cost construction, and suitable for scanning operations in the Ku-band i.e. 13.515GHz + 25 MHz frequency, in which the mode transducers of compact and rugged construction have been incorporated to ensure reliable and durable performance of the joint in converting the microwaves of TE 10 mode in rectangular waveguides into microwaves of rotationally symmetric orthogonal modes TM 01 and TE 01 in a circular waveguide at the signal input ends, and reconverting the microwaves of rotationally symmetric orthogonal modes TM 01 and TEOl in a circular waveguide into microwaves of TE 10 mode in rectangular waveguides at the signal output ends.
The rotationally symmetric orthogonal modes TM 01 and TEOl of microwaves excited in the circular waveguides are higher modes. In circular waveguides, the dominant mode having the lowest cut off frequency is TE 11.
In the invented rotary joint microwaves of higher mode TM 01 have been excited in circular waveguide by using an axial probe from microwaves of mode TE 10 in rectangular waveguide of one channel of input signal and microwaves of higher mode TEO 1 in circular waveguide have been excited by using two axial slots in the wall of the circular waveguide from the microwaves of TElO mode of rectangular waveguide of the other channel of input signal.
Microwaves of dominant mode TEIl in the circular waveguide have not been excited from microwaves of mode TElO in rectangular waveguides of the two channels of input signal for the reasons, such as, (a) the higher mode TM 01 has a relatively high power carrying capacity combined with circular symmetry with the other higher mode TE 01, (b) the return loss as well as the insertion loss of signal energy at the rotary joint, and variation in insertion
loss of signal energy with rotation of circular waveguide are lowered by exciting the higher modes TM 01 and TE 01, (C) isolation between the signals of the two input channels is improved by exciting TM 01 mode for one channel and TE 01 mode for the other channel; and (d) there is an appreciable cross-talk between the signals of the two input channel, if the dominant mode TE 11 is excited in the circular waveguide from TE 10 mode of both the input channels.
In WO 2005/051 604 A7, a method and assembly device for producing a rotary joint between a drive element and a flange is described. A bolt of the drive element is driven into a nut of the flange until the bolt is drawn into a bore in the flange.
In US- 4,800,389 a rotary joint formed by a commutator having conductive brushes and rings for connecting the antenna system with processing circuitry of a RADAR apparatus is described for avoiding the loss of signal energy encountered in the conventional rotary joints for providing microwave coupling between the antenna and circulator of a RADAR apparatus.
In KR 2005 0113769 a rotary joint for feeding microwave signals into an antenna system has been disclosed.
In US 4 163 961, a rotary joint comprising an assembly of non- contacting overlapping sleeves which are electrically coupled to one another at microwave frequencies and rotatable relatively about an axis is disclosed. A pair each of inner and outer tubular conductors are disposed co-axially to form waveguide cavities, one end of which is connected to the said sleeves and the other end is fed with input signals excited in selected modes.
The conventional dual-or multi-channel rotary joints realized in coaxial configuration have the main limitation in that these are applicable for propagating microwaves of lower frequency bands only, such as L-, C- and X- bands. The realisation of such joints for propagating microwaves of Ku-and still higher frequency bands is difficult, because of the reduced gap of lmm or so required between the inner and outer conductors of the co-axial configuration, with consequent reduction of the power handling capacity of such joints.
The realization of conventional rotary joints is generally difficult and expensive because of the complexity of their design.
The return loss and insertion loss of signal energy propagated in conventional rotary points is relatively high together appreciable variation in the insertion loss of signal energy with rotation of joints. The isolation between signals of channels is also relatively low.
With a view to overcoming the limitations of the conventional rotary joints in coaxial configuration, the rotary joint of the present invention has been realized by eliminating the inner conductor of the coaxial configuration, that is, by using a circular/cylindrical waveguide in which microwaves of higher mode TM 01 are excited using a co-axial probe, integrally constructed with a metallic post or a multi-section ridge of stepped structure provided in a rectangular waveguide through which microwaves of mode TE 10 of one channel of input signal are fed into the circular waveguide.
Microwaves of higher mode TE 01 are excited in the cicular waveguide by using axial slots in the wall thereof from microwaves of mode TElO in the rectangular waveguide of the other channel of input signal.
The object of the present invention is to provide a dual-channel rotary joint of relatively simple design, rugged and low-cost construction, light weight
and reduced dimensions, suitable for operation in the Ku-band of microwaves in space-borne scanning antennas.
The other object is to provide a rotary joint in which the return and insertion loss of signal energy is lowered, the variation in insertion of signal energy with rotation of the joint is reduced, and the isolation between the signals propagated through the joint is increased.
Another object is to provide a rotary joint of reliable and durable performance under low pressure environment of the upper space.
The dual-channel rotary joint according to the present invention comprises two circular waveguides, called upper cylindrical waveguide and lower cylindrical waveguide, rotatably engaged at the adjoining overlapping ends thereof in a ball bearing. At the other end of each cylindrical waveguide, an end cover with a co-axial probe, and rectangular waveguides, and axial slots on the wall thereof are provided.
- The input signals of two channels are fed at the top end of the upper cylindrical waveguide through two rectangular waveguides.
The output signals are delivered at the bottom end and bottom wall of the lower cylindrical waveguide through two channels of rectangular waveguides.
The probe introduced in the upper cylindrical waveguide acts as the transducer for exciting microwaves of mode TM 01 from the microwaves of mode TElO supplied through the rectangular waveguide of one channel of input signal and the probe introduced in the lower cylindrical waveguide acts as the transducer for converting the microwave of mode TM 01 into microwaves of mode TE 10 delivered into rectangular waveguide of one channel of output signal.
Microwaves of mode TE 10 fed into the upper cylindrical waveguide through the rectangular waveguide of the other channel of input signal are converted into microwaves of mode TEOl in circular waveguide by two axial slots provided in the wall of the upper cylindrical waveguide. Microwaves of mode TEOl are converted into microwaves of mode TElO by two axial slots provided in the wall of the lower cylindrical waveguide and delivered into rectangular waveguide of the other channel of output signal.
The probes introduced into the upper and lower cylindrical waveguides are each attached to a multi-section stepped ridge acting as impedance matching transformer and provided as an integral part of a rectangular waveguide, mechanically connected one each to the upper and the lower cylindrical waveguides.
The provision of the probes of mechanically integrated structure and the axial slots in the wall of the upper and lower cylindrical waveguides makes the invented rotary joint compact and rugged to ensure reliable and durable performance thereof in the space-borne scanning antennas.
Thus the present invention provides a dual-channel rotary joint for space-borne scanning antennas, characterised in that the rotary joint comprises an upper cylindrical waveguide attached to rectangular waveguide with a 90° - bend for one channel of input signal and to a rectangular waveguide for the other channel of input signal, and a lower cylindrical waveguide attached to rectangular waveguides for one channel of output signal and to rectangular waveguides for the other channel of output signal, the top part of the said lower cylindrical waveguide being rotatably engaged with the bottom part of the said upper cylindrical waveguide in a ball bearing, an axial probe and two axial slots being provided in the said upper cylindrical waveguide for exciting respectively microwaves of modes TM 01 and TEOl from microwaves of mode TElO fed through rectangular wave guides for both channels of input signal,
and an axial probe and two axial slots being provided in the said lower cylindrical waveguide for converting respectively microwaves of modes TMOl and TEOl into microwaves of TElO delivered through rectangular waveguides of both channels of output signal.
The invented dual-channel rotary joint is described in detail without restricting the scope of the invention in any manner with reference to a particular embodiment of the joint illustrated in the accompanying drawings in which-
Figure 1 is a three-dimensional CAD view of the invented joint;
Figure 2(a) is a three-dimensional CAD view of the upper stationary part of the invented j oint;
Figure 2(b) is a three-dimensional CAD view of the lower rotatable part of the invented joint;
Figure 3 (a) shows the two-dimensional sketch,
Figure 3(b) shows sectional sketch,
Figure 3(c) shows three-dimensional sketch of the invented joint;
Figure 4 is an exploded view of the upper stationary part of the invented joint; and
Figure 5 is an exploded view of the lower rotatable part of the invented joint.
Referring to Fig. 1, the upper stationary part of the invented joint comprises two signal input ends (5), rectangular waveguide (22) with 90°- bend (1) as channel of one input signal, rectangular waveguide (23) as channel of other input signal, upper cylindrical waveguide (4) with end cover (2) and
interface mounting lugs (3); and the lower rotatory part comprises the lower cylindrical waveguide (6) with end cover (7), side tapered rectangular waveguide (8), side cross rectangular waveguide (10) and side tapered rectangular waveguide (12) forming one channel of output signal and bottom- middle top rectangular wavegide (9), bottom straight rectangular waveguide
(11) forming the other channel of output signal, and output end (13).
Referring to Figs. 2(a) and 2(b), pressurized flanges (14) are attached one each at the feed ends of rectangular waveguides (22, 23) and output end of rectangular waveguides (11, 12) for interfacing the signal input sources and output networks .
The inner surface of a ball bearing is fitted on the outer surface (15) of the upper cylindrical waveguide (4), and the outer surface of the ball bearing is fitted on the inner surface (16) of the lower cylindrical waveguide (6).
Referring to Figs. 3(a), 3(b) and 3(c), the lower cylindrical waveguide (6) along with rectangular side waveguide (8), middle-top waveguide (9), side cross, waveguide (10), straight waveguide (11) and side tapered waveguide
(12) which are integrally connected thereto is rotatably coupled through ball bearing (20) with the upper stationary cylindrical waveguide (4) along with rectangular waveguides (22, 23) having 90°-bend (1) and signal feed ends (5), which are integrally connected thereto.
Upper cylindrical waveguide (4) is provided with two axial slots (25,
26) on the wall thereof at locations where the phase of the electric field in the waveguide is the same, which are used for exciting microwaves of mode TEOl from microwaves of mode TElO fed thereinto through rectangular waveguide (23).
The probe (24) is axially introduced into upper cylindrical waveguide (4) to excite therein microwaves of mode TMOl from microwaves of mode TElO fed thereinto through rectangular waveguide (22) having 90°- bend (1).
The probe (24;) is introduced axially into the lower cylindrical waveguide (6) to convert microwaves of mode TMOl into microwaves of mode TElO delivered through rectangular waveguides (9 and 11).
Axial slots (27, 28) are provided in the wall of lower cylindrical waveguide (6) to convert microwaves of mode TEOl into microwaves of mode
TElO delivered through rectangular waveguides (8, 10 and 12). Slots (27, 28) are located on the wall of lower cylindrical waveguide where the phase of the electric field is the same.
Microwaves of mode TM 01 having magnetic lines of force in planes perpendicular to the axis of cylindrical waveguides are excited by using axial probes and microwaves of mode TEOl having electric lines of force in planes perpendicular to the axis of cylindrical waveguides are excited by using axial slots. \ •
Multi-section stepped ridges (19 and 19;) are integrally attached to inner surface of rectangular waveguides (22, 9) and also to probes (24,24;) respectively and are provided for matching the impendance at the output and input ends of the probes and also to make the joint compact and mechanically rugged to ensure its reliable and durable performance in space-borne scanning antennas, with reduced return and insertion loss, and variation in insertion loss with rotation of joint, of the signal energy propagated therethrough, as well as to increase the power handling capacity thereof.
The rectangular waveguides used in the invented joint are of type WR62 and provided with pressurized interfacing flanges (14) shown in Figs. 2(a) and
2(b) to make the structure of the rotary joint mechanically rigid and to reduce leakage of signal energy at the interfaces thereof.
The lower cylindrical waveguide (6) with the associated rectangular waveguides (8, 9, 10, 11, 12) is rotatable with respect to the upper cylindrical waveguide (4) over an angle of 360° (WoW).
The gap between the outer surface of the upper cylindrical waveguide
(4) and inner surface of the lower cylindrical waveguide (6) have been critically selected to prevent multipaction breakdown of the rotary joint in handling the specified signal energy propagated therethrough in the low- pressure environment of the upper space.
A non-contacting type RF choke joint (not-shown) is provided adjacent the overlapping surfaces of the upper and lower cylindrical waveguides (4, 6) to reduce leakage of microwave signals through the gap at the rotary joint.
Referring to Fig. 4, the upper cylindrical waveguide (4) is provided with a ring (18) and a lock ring ( 17) at the bottom end thereof.
Referring to Fig 5, the ball bearing (20) with ring (21) is provided in the gap between the overlapping surfaces of the upper and lower cylindrical waveguides to engage the lower cylindrical wavegide (6) rotatably with the upper cylindrical waveguide (4) (shown in Fig. 5).
The ball bearing used in the rotary joint is of angular contact type having inner diameter 40 mm and outer diameter 52 mm.
The rotary joint is of height 225 mm, maximum diameter 90mm and weight 600 gm, and is capable of handling microwave peak power 110 watt and average power 30 watt.
The specified values, simulated results and measured results (obtained on laboratory model of the invented rotary joint) on the operational parameter of the invented rotary joint are presented in Table I, from which it is noted :-
(a) the joint is operable at the frequency range of 13.515 GHz + 25 MHz;
(b) the return loss of signal energy is less than -19 db;
(c) the insertion loss of signal energy is 0.36 db maximum ;
(d) the variation of insertion loss of signal energy with rotation of the joint over 360° (WoW) is 0.10 db; (e) isolation between signals of the two channels is 41 db.
The advantageous features of the invented dual=-channel rotary joint are
1. Reduced weight and compact size
2. Rugged construction
3. Reliable and durable performance 4. Reduced insertion and return losses of signal energy
5. Reduced variation of insertion loss of energy with rotation over 360° (WoW)
6. Increased isolation between the signals of two channels propagated through the joint.
The invented rotary joint is suitable more specifically for scanning a pencil beam scatterometer antenna for space-borne remote sensing application in the retrieval of ocean wind vector.
Table -I: The Specified Values. Simulated Results and Measured Results (obtained on the laboratory model) on the Operational Parameters of the Invented Dual Channel Rotary Joint
Claims
1. A dual-channel rotary joint for space-borne scanning antennas, characterised in that the rotary joint comprises an upper cylindrical waveguide (4) attached to a rectangular waveguide (22) with a 90° bend (1) for one channel of input signal and to a rectangular waveguide (23) for the other channel of input signal, and a lower cylindrical waveguide (6) attached to rectangular waveguides (9, 11) for one channel of output signal and to rectangular waveguides (8, 10, 12) for the other channel of output signal, the top part of the said lower cylindrical waveguide being rotatably engaged with the bottom part of the said upper cylindrical waveguide in a ball bearing (20), an axial probe (24) and two axial slots (25, 26) being provided in the said upper cylindrical waveguide for exciting respectively microwaves of modes TM 01 and TE 01 from microwaves of mode TElO fed through rectangular waveguides (22,23) for both channels of input signal and an axial probe (247) and two axial slots (27, 28) being provided in the said lower cylindrical waveguide for converting respectively microwaves of modes TMOl and TEOl into microwaves of mode TElO delivered through rectangular waveguides (9, 11) and (8, 10, 12) for both channels of output signal.
2. The rotary joint as claimed in claim 1, wherein the rectangular waveguide (22) and the rectangular waveguide (9) are provided respectively with multi-section stepped ridge (19) and multi-section stepped ridge (197) attached integrally to the inner surfaces thereof, as impedance matching transformers.
3. The rotary joint as claimed in claim 2, wherein the axial probe (24) is attached integrally to the ridge (19) and the axial probe (24;) is attached integrally to the ridge (19;).
4. The rotary joint as claimed in claim 3, wherein axial slots (25, 26) are provided in the wall of upper cylindrical waveguide (4) at locations where the phase of the electric field of microwaves therein is the same, and axial slots (27, 28) are provided in the wall of lower cylindrical waveguide (6) at locations where the phase of the electric field of microwaves therein is the same.
5. The rotary joint as claimed in claim 1, wherein the ball bearing (20) is of angular contact type having inner diameter 40mm and outer diameter 52mm.
6. The rotary joint as claimed in claim 5, wherein the lower cylindrical waveguide is rotatable over 360° (WoW) with respect to the upper cylindrical waveguide.
7. The rotary joint as claimed in claim 6, wherein the rectangular waveguides used are of type WR62 and provided with pressured interfacing flanges at the signal feed and signal delivery ends thereof.
8. The rotary joint as claimed in claim 7, which is adapted to operate in signal frequencies 13.515 GHz + 25 MHz at an insertion loss of signal energy 0.36 db maximum, return loss of signal energy less than 0.19 db, isolation between the two signal channels 41 db, variation in the insertion loss of signal energy with rotation over 360° (WoW) 0.10 db, peak signal power 110 watt and average signal power 30 watt.
9. The rotary joint as claimed in claim 8, which is of height 225mm, maximum diameter 90 mm and weight 600 gm.
10. A dual-channel rotary joint for space-borne scanning antennas, substantially as herein described and illustrated in Figures 1, 2(a), 2(b), 3(a), 3(b), 3(c), 4 and 5 of the accompanying drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IN567/CHE/2007 | 2007-03-19 | ||
| IN567CH2007 | 2007-03-19 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2008114281A2 true WO2008114281A2 (en) | 2008-09-25 |
| WO2008114281A3 WO2008114281A3 (en) | 2009-12-30 |
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ID=39766588
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/IN2008/000161 WO2008114281A2 (en) | 2007-03-19 | 2008-03-17 | Dual channel rotary joint for space borne scanning antenna |
Country Status (1)
| Country | Link |
|---|---|
| WO (1) | WO2008114281A2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104409801A (en) * | 2014-12-11 | 2015-03-11 | 四川龙瑞微电子有限公司 | Waveguide rotary joint |
| CN106410333A (en) * | 2016-10-19 | 2017-02-15 | 京航泰（北京）科技有限公司 | Single-channel waveguide rotating joint |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2853681A (en) * | 1953-01-30 | 1958-09-23 | Gen Electric | Dual frequency rotatable joint |
| GB2218854A (en) * | 1988-05-21 | 1989-11-22 | Gen Electric Co Plc | Waveguide apparatus |
| GB2274549A (en) * | 1992-12-04 | 1994-07-27 | Sg Microwaves Inc | Waveguide rotary joint |
| EP1542310A1 (en) * | 2002-09-20 | 2005-06-15 | Murata Manufacturing Co., Ltd. | Antenna device and transmitting/receiving device |
-
2008
- 2008-03-17 WO PCT/IN2008/000161 patent/WO2008114281A2/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2853681A (en) * | 1953-01-30 | 1958-09-23 | Gen Electric | Dual frequency rotatable joint |
| GB2218854A (en) * | 1988-05-21 | 1989-11-22 | Gen Electric Co Plc | Waveguide apparatus |
| GB2274549A (en) * | 1992-12-04 | 1994-07-27 | Sg Microwaves Inc | Waveguide rotary joint |
| EP1542310A1 (en) * | 2002-09-20 | 2005-06-15 | Murata Manufacturing Co., Ltd. | Antenna device and transmitting/receiving device |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104409801A (en) * | 2014-12-11 | 2015-03-11 | 四川龙瑞微电子有限公司 | Waveguide rotary joint |
| CN106410333A (en) * | 2016-10-19 | 2017-02-15 | 京航泰（北京）科技有限公司 | Single-channel waveguide rotating joint |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2008114281A3 (en) | 2009-12-30 |
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