Title of Invention

RADIO FREQUENCY COUPLER FOR TRANSFERRING RF POWER

Abstract A radio frequency (RF) coupler comprises a first electrically conductive track (21) having a pair of terminations and a second electrically conductive track (31) having a pair of terminations. In one embodiment (Figure 1) the first and second tracks (21,31) are actuate, the first track (21) being modulated on a circuit board (23) fixed to a rotary shaft (11) and tl1.e second track (31) being mounted on a circuit board (33) supported on a coaxial bearing relative to which the shaft rotates. The two tracks (21, 31) are in radically- overlapP3.ng relationship. In another embod3.ment (Figure 2) the two tracks (21', 3:L') are mounted on coaxial sleeves. The RF coupler is used to transfer RF power from a first circuit on the shaft to a second circuit relative to which the shaft can rotate.
Full Text



This invention relates to a radio frequency (RF) coupler and the invention relates particularly, though not exclusively, to an RF coupler for transferring RF power between a first circuit on a rotary shaft and a second circuit relative to which the shaft can rotate.
The invention also relates to a tunable notch filter.
International patent application no. PCT/GB91/00328 discloses an apparatus for measuring dynamic torque in a rotatable shaft. The apparatus comprises a surface acoustic wave (SAW) transducer mounted on the shaft, and requires coupling means for the efficient transfer of RF power between the transducer and processing circuitry which does not rotate with the shaft.
According to one aspect of the invention there is provided a radio frequency (RF) coupler for transferring RF power between a first circuit on a rotary shaft having a rotation axis (x-x) and a second circuit relative to which the shaft can rotate, the RF coupler comprising, a first RF transmission line arranged to rotate with said rotary shaft about said rotation axis (x-x) and for connection to said first circuit, and a second RF transmission line relative to which said first transmission line can rotate and for connection to said second circuit, wherein said first and second transmission lines comprise first and second electrically conductive tracks arranged coaxially around said rotation axis (x-x) in substantial mutually overlapping relationship to provide RF coupling between the first and second RF transmission lines characterized in that each said electrically conductive track has a gap defining a pair of ports in the track, one said port being connectable to a respective said circuit and another said port being connected to a termination for reflecting RF power.

According to another aspect of the invention there is provided a radio frequency (RF) coupler comprising a first RF transmission line mounted on a rotary shaft having a rotation axis and a second RF transmission line relative to which the first RF transmission line can rotate, wherein said first and second RF transmission lines comprise first and second electrically conductive tracks arranged coaxially around said rotation axis in substantial overlapping relationship, characterized in that each said track has a gap defining a pair of ports in the track, one of said ports being connected to a termination for reflecting RF power, and each said track has a periodic undulation around the rotation axis, the undulation being formed by an integer number n of segments each subtending an angle A = 360°/n at the rotation axis, and said gap is formed in one of the segments thereof
According to a yet further aspect of the invention there is provided notch filter tunable to a desired frequency within a predetermined RF frequency band, comprising a first RF transmission line and a second RF transmission line, wherein said first and second RF transmission lines respectively comprise first and second electrically conductive tracks arranged coaxially about a rotation axis (x-x) in substantial mutually overlapping relationship to provide RF coupling between the first and second RF transmission lines characterized in that each said electrically conductive track has a gap defining a pair of ports in the track, one of said ports being connectable to an input or an output of the notch filter and another of said ports being connected to a termination for reflecting RF power, and said first and second electrically conductive tracks being capable of relative rotation about said rotation axis (x-x) to tune the notch filter to the desired frequency.

The first and second electrically conductive tracks may comprise continuous electrically conductive layers or films formed by any suitable deposition technique such as screen printing or electrodeposition. Alternatively the tracks may be turned or wire wound.
Embodiments according to the invention are now described, by way of example only, with reference to the accompanying drawings in which :
Figure 1 shows a longitudinal sectional view through one embodiment of an RF coupler according to the invention;
Figure 2 shows a longitudinal sectional view through another embodiment of an Rf coupler according to the invention;
Figure 3 shows a simplified representation of the RF couplers shown in Figures 1 and 2;
Figure 4 is a schematic representation of the transmission lines 20, 30 shown in figure 3;
Figure 5 is a consolidated representation of the transmission lines shown in figure 4;

Figure 6 shows the coupler response for a 3dB coupler having
a line length 6 =— ;
2
Figure 7 shows the coupler response for a 3dB coupler having a reduced line length;
Figure 8 shows the coupler response for a 4dB coupler having a reduced line length,
Figure 9 shows an alternative form of track for use in a rotary coupler in accordance with the invention,
Figures 10(a) to 10 (c) illustrate different modulation line shapes obtained using tracks of the form shown in Figure 9,
Figures 11a and lib show nulls in the coupler response for two different values of rotation angle, and
Figure 12 shows a tunable notch filter.
Figures 1 and 2 show two alternative embodiments of an RF coupler according to the invention.
In each embodiment, the RF coupler is required to transfer RF power between a first RF circuit (not shown in the drawings) mounted on a rotary shaft 11 and a second RF circuit (also not shown) relative to which the shaft 11 can rotate.
The RF coupler comprises two coupled transmission lines 20,30. Line 20 is mounted on the rotary shaft 11 for rotation therewith, whereas line 30 is mounted on a fixed coaxial

bearing 12.
In the embodiment of Figure 1, each transmission line 20,30 comprises an arcuate, electrically-conductive track 21,31 and a ground plane 22,32 which are provided on opposite sides of a annular circuit board 23,33. One of the circuit boards, 23 is fixed to the rotary shaft 11 and the other circuit board 33 is fixed to the bearing 12. The circuit boards 23,33 are assembled so that the tracks 21,31 and the ground planes 22,32 lie in mutually parallel planes, orthogonal to the rotation axis x-x of shaft 11, with the tracks 21,31 facing inwardly. The tracks are separated by a dielectric spacer 34. Alternatively the tracks may be separated by an air space.
Each track 21,31 is in the form of an annulus and has a narrow gap defining a discontinuity in the annulus. The gaps are not shown in Figure 1, but are best illustrated in the schematic representation of tracks 21,31, shown in Figure 3, where the gaps are referenced G^ and Gj respectively.
The opposite ends of track 21 form a pair of terminations in the track and define ports Pi and P3 in the first transmission line 20. Likewise, the opposite ends of track 31 form a pair of terminations in the track and define ports P2,P4 in the second transmission line 30.
In this embodiment, ports P1 and P4 are connected to the first and second RF circuits via lines L1 and L4 respectively, whereas ports P2 and P3 are both connected to a short circuit via the ground planes 23,33 and lines L2,L3. Alternatively, ports P2 and P3 could be open circuit.

The tracks 21,31 have the same radial dimensions, and they are arranged coaxially on the rotation axis x-x of shaft 11. Accordingly, the tracks remain in substantial, radially-overlapping relationship over a complete revolution of the shaft.
The coupling between the transmission lines 2 0,30 depends, inter alia, upon such factors as the radial width w, axial spacing s and the degree of overlap between the respective tracks 21,31.
The embodiment shown in Figure 2 has a different geometry. In this case, the rotary shaft 11 and the fixed, coaxial bearing 12 have closely-fitting, cylindrical, dielectric sleeves 35,36. One electrically conductive track 21' is provided on the outer surface of sleeve 35 and another electrically conductive track 31' is provided on the inner surface of sleeve 36, and the tracks 21',31' are separated by a cylindrical dielectric spacer 37 or, alternatively, by an air space.
Tracks 21',31' are in the form of coaxial cylinders. However, as in the embodiment of Figure 1, each track has a narrow gap creating a discontinuity in the cylinder wall and forming a pair of terminations in the track. Again, the opposite ends of track 21' define ports P^ and P3 in transmission line 20 and the opposite ends of track 31' define ports P2 and P4 in transmission line 30.
The tracks 21',31' have the same axial width w and are aligned

in the axial direction. Accordingly, they will remain in substantial, axially-overlapping relationship throughout a complete revolution of the rotary shaft 11.
In this embodiment, ground planes are provided by the outer surface of shaft 11 and the inner surface of bearing 12, and these components are themselves connected to a short circuit.
From an operational standpoint, the embodiments described with reference to Figures 1 and 2 are the same. However, the embodiment described with reference to Figure 1 is preferred if there is radial play between the rotary shaft 11 and the coaxial bearing 12, whereas the embodiment described with reference to Figure 2 is preferred if there is axial play between these components.
An analysis based on the theory of coupled transmission lines suggests that the coupler response may vary as shaft 11 rotates, and it is of course desirable that such variation be made as small as is possible.
Figure 3 shows a simplified representation of the RF couplers described with reference to Figures 1 and 2. As already explained, each transmission line 20,30 has a narrow gap Gi,G2 forming a pair of terminations. In Figure 3, the gaps 0^,02 are shown to subtend an angle ij; at the rotation axis x-x. The magnitude of T|; will, of course, vary as shaft 11 rotates.
The analysis which follows takes account of RF power reflected at the interfaces presented by the terminations.



The values of these coefficients depend on the rotation angle and affect the coupling between the two transmission lines 20,30.
Figure 5 is a consolidated representation of the transmission lines 2 0,30 derived from Figure 4, and shows coefficients corresponding to the resultant RF power transferred between different pairs of ports.
From this representation it can be determined that the coefficient S41, representing RF power transferred between ports Pi and P4, is given by the expression

Expressed generally, and

e '■'^ is the propagation phase factor for the transmission lines, and
p is the reflection coefficient corresponding to the characteristic impedance of the coupled transmission lines, given by the expression

(5)
where is the system characteristic impedance (assumed to be although other values of characteristic impedance could be used).
It can be shown that the RF couplers described with reference to Figures 1 and 2 both have a characteristic impedance Z^g given by the expression

where e is the dielectric constant,
w,b and s having the meanings assigned to them in the
drawings, and

By combining equations (2)-(7) above, the transfer coefficient (S41) , and so the coupler response, can be determined for a complete revolution of the rotary shaft 11, i.e. for values of ijf in the range from 0° to 360°.
By way of illustration, these determinations have been made
using parameters based on a standard 3dB hybrid coupler having
fixed transmission lines, which requires that 0=— and
2

By equating equations (3) and (4) , and applying equation (5) , it can be seen that the requirement that leads to a reflection coefficient p of 0.414, corresponding to a characteristic impedance (assuming
Figure 6 shows the resultant coupler response. This shows that when the terminations are aligned, the
coupler is effectively lossless. However, as i|r increases the coupling between the transmission lines becomes progressively worse and the response falls, dropping to a minimum value of -4dB when = 180°.
Surprisingly, it is found that the coupler response can be
significantly improved if the line length 6 is reduced from
the standard value, —. In fact, for a 3dB coupler the
2 optimum line length is found to be only 62% of the standard
value. Figure 7 shows the improved coupler response, which is
never less than -0.l6dB. Due to the periodic nature of the
frequency response of couplers in general, longer line
lengths, periodic in could alternatively be used. Therefore, in general the optimum line length will differ significantly from where n is an integer.
It will, of course, be appreciated that in an alternative implementation of the present invention, the RF coupler may have transmission lines that are more or less tightly coupled than is the case in a 3dB coupler.
Less tightly coupled transmission lines may be more

appropriate where manufacturing tolerances do not permit a very narrow spacing s between the transmission line tracks. In the case of a 4dB coupler, the optimum line length is found to be 93% of the standard value, —. As shown in Figure 8, this coupler still has a useful response which is never less than 0.37dB.
In general, couplers having loosely coupled transmission lines
have smaller characteristic impedances X^. However, for
values of Z^g ^ 97.7Q optimisation of the line length 0 to a
value different from the standard value, — is not possible,
2 because the latter value always gives the optimum result.
Nevertheless, for a coupler having a characteristic impedance of Zoe = 97.7Q the variation of coupler response with rotation angle \|; is still only 0.47 dB.
In the embodiment of Figure 1, each track 21,31 is in the form
of an annulus. In a different embodiment, shown in Figure 9,
each track is constellated being made up of an integer number
n of identical segments, where each segment subtends an angle A 360° n
The two tracks are identical so that if the rotation angle i|;=0° or is an integer number of A (i.e. i|j=^A) they will be in perfect overlapping relationship, giving the optimum coupling. As the rotation angle ijf changes from this value, the extent of overlap is reduced and the coupling between the tracks decreases, the coupling being a minimum when the rotation angle \(f is a half integer multiple of A (/.e.t|;=(*:+'/2)A) .

With this arrangement, the coupler response will be modulated at a frequency of n cycles for each revolution of the rotary shaft 11, and so provides a measure of the rotation angle i|;.
The line shape of the modulation depends upon the shape of the segments in the tracks. Figure 10a shows the modulation line shape derived using triangular segments of the form shown in Figure 9, Figure 10b shows the comparatively smooth modulation line shape obtained using relatively shallow triangular segments, and Figure 10c shows the line shape obtained using segments having a castellated, i.e. square or rectangular profile, and in this case the phase as well as the amplitude is modulated.
In another embodiment, two sets of tracks 21,31 are provided, one track in each set being mounted on the rotary shaft 11 and the other track in each set being mounted on the fixed bearing 12. The input to, and the output from the coupler are connected to tracks which are either both mounted on the rotary shaft 11 or both mounted on the fixed bearing, and the remaining tracks are electrically interconnected. With this arrangement RF power is transferred from the input to the output via the electrically interconnected tracks.'
In one implementation of this embodiment, the tracks 21,31 in one of the sets are constellated, as already described, whereas the tracks in the other set are annular, as described with reference to Figure 1. As described with reference to Figures 9 and 10, the coupler has a modulated output giving a measure of the rotation angle of rotary shaft. However, in this implementation, the input and the output are both either

^i.1 uiic iuudJLy aiiciLt. x± or on cne tixea JDearing 12, and this may be advantageous in some applications.
In another implementation of the embodiment, both sets of
tracks are constellated. The sets of tracks are identical,
except that the tracks in one set are slightly offset about
the rotation axis x-x of shaft 11 with respect to the tracks
in the other set. With this arrangement, the coupler output
consists of two modulated signals each of a form shown in
Figures 10(a) to 10(c). Provided the angular offset between
the two sets of tracks is not equal to —, the relative phases
2
of the modulated signals give an indication of the sense of
shaft rotation, the optimum angular offset being —.
4
It has been found that the coupler response exhibits a sharp notch over a range of values of line length 6 and rotation angle ij;, and the null is particularly prominent when the coupling is relatively tight. As the rotation angle t|; is varied from a minimum value ^\f^^^ to a maximum value i|f„axi so the null is observed to shift continuously from a maximum value 6n,ax to a minimum value 0n,in. Figures 11a and lib illustrate how the position of the notch shifts from a high value 0, to a lower value 82 as the rotation angle T|; changes from 90° to 180°, for a coupler having a characteristic impedance of I80Q. In general, it has been observed that while
Since the value of 6 is proportional to frequency, it is possible, in an alternative application, to use the coupler as a notch filter which can be tuned over a frequency band

defined by upper and lower limits, , simply by
varying the rotation angle ij;.
A notch filter based on the embodiments of Figures 1 and 2 has the drawback that the input to and the output from the filter must rotate with respect to each other, and for some applications this may be impractical.
Figure 12 shows another embodiment of the tuned notch filter in which input and output terminals 1,0 of the filter are not required to rotate with respect to each other.
In this embodiment, the filter comprises four circuit boards C1-C4_ each having an annular, electrically-conductive track 41,42,43,44 of the form described hereinbefore - as before each track has a pair of terminations.
Circuit boards C1,C4 are fixed together in spaced-apart relationship by a bushing 45 and an associated fastener 46. Circuit boards C3,C3 , which are positioned between circuit boards C1,C4, are also fixed together and are rotatable with respect to boards C-^,C^^ about an axis Y-Y. Circuit boards Ci,C2 are separated by a dielectric spacer 47 and circuit boards C3,C4 are separated by a dielectric spacer 48.
The circuit boards are arranged coaxially , in parallel so that the respective pairs of tracks 41,42; 43,44 are in radially-overlapping relationship. Tracks 42,43 on boards C2,C3 are electrically interconnected . The input and output terminals 1,0 are both provided on the same circuit board C^, with the input terminal I being connected to track 41 and the

output terminal 0 being connected to track 44 via a link 49.
If the tracks 41,42,43,44 are all the same length, and the terminations in the tracks are aligned, the filter response will exhibit a single, relatively sharp notch (as shown in Figures 9a and 9b) which can be tuned to a desired frequency by rotating the interconnected circuit boards C2.C3 relative to the circuit boards C1,C4. If, on the other hand, the respective pairs of tracks 41,42; 43,44 have different lengths and/or the terminations in tracks 42,43 and/or 41,44 are offset with respect to each other, the filter response will exhibit two distinct notches, or a single, but relatively wide notch if the differences in track length and/or the extent of the offset are slight.
A similar arrangement based on multiple coaxial, cylindrical tracks of the form shown in Figure 2, is also envisaged.
In the foregoing embodiments, the terminations are formed by gaps in the electrically conductive tracks. Alternatively, continuous, unbroken tracks may be used. In this case, a single connection made to each track forms a common termination in the track such that the pairs of ports P1,P3; P2,P4 are also common.
It will be appreciated from the foregoing that the described RF coupler is highly versatile. In one application, the RF coupler can be used to transfer RF power between fixed and rotating circuits, and to provide optimum coupling at all angles of rotation. In other applications, the coupler can be used to provide a measure of angular rotation and in yet

further applications the coupler provides a tunable notch filter having fixed or relatively rotatable input and output terminals.


WE CLAIM :
A radio frequency (RF) coupler for transferring RF power between a first circuit on a rotary shaft (11) having a rotation axis (x-x) and a second circuit relative to which the shaft (11) can rotate, the RF coupler comprising, a first RF transmission line (20) arranged to rotate with said rotary shaft (11) about said rotation axis (x-x) and for connection to said first circuit, and a second RF transmission line (30) relative to which said first transmission line (20) can rotate and for cormection to said second circuit, wherein said first and second transmission lines (20, 30) comprise first and second electrically conductive tracks (21, 31; 21', 31') arranged coaxially around said rotation axis (x-x) in substantial mutually overlapping relationship to provide RF coupling between the first and second RF transmission lines (20, 30) characterized in that each said electrically conductive track (21, 31; 21', 31') has a gap (G1, G2) defining a pair of ports (P1, P3; P2, P4 ) in the track, one said port being connectable to a respective said circuit and another said port being connected to a termination for reflecting RF power.
The coupler as claimed in claim 1, wherein said first said and second tracks (21, 31) are supported in substantially parallel planes orthogonal to the rotation axis (x-x) of the rotary shaft (11) and are in radially-overlapping relationship.
The coupler as claimed in claim 2, wherein said first and second tracks (21, 31) are substantially annular.

The coupler as claimed in claim 2, or 3, wherein each said track (21,31) has a substantially periodic undulation around said rotation axis (x-x), the undulation being formed by an integer number n of segments each subtending an angle A = 360°/n at the rotation axis (x-x) and wherein said gap (G1, G2) is formed in one of said segments.
The coupler as claimed in any one of claims 2 to 4, wherein said first track (21) is mounted on a first circuit board (23) fixed to the rotary shaft (11) and said second track (31) is mounted on a second circuit board (33) relative to which said first circuit board (23) can rotate.
The coupler as claimed in claim 5, wherein said first RP transmission line (20) comprises a first ground plane (22) provided on one side of said first circuit board (23) and said first track (21) provided on the opposite side of said first circuit board (23), and said second RF transmission line (30) comprises a second ground plane (32) provided on one side of said second circuit board (33) and said second track (31) provided on the opposite side of said second circuit board (33).
The coupler as claimed in any one of claims 2 to 6, wherein said first and second tracks (21, 31) are separated by a dielectric spacer (34).
The coupler as claimed in claim 1, wherein said first and second tracks (21', 31') are arranged in axially-overlapping relafionship.
The coupler as claimed in claim 8, wherein said first and second tracks (2 r, 31') are substantially cylindrical.

The coupler as claimed in claim 8 or 9, comprising a first dielectric cylindrical sleeve (35) fixed to said rotary shaft (11) and a second dielectric cylindrical sleeve (36) arranged coaxially around the first sleeve (35) and relative to which the first sleeve (35) can rotate, said first and second tracks (21', 31') being respectively provided on the outer and inner surfaces of the first and second sleeves (35, 36).
The coupler as claimed in any one of claims 8 to 10, wherein said first and second tracks (21', 31') are separated by a cylindrical dielectric spacer (37).
The coupler as claimed in any one of claims I to 11, wherein said first and second tracks (21, 31; 21', 31') have a line length 0 which differs from {n+H)K, where n is 0, 1, 2, 3....
The coupler as claimed in claim 12, wherein said first and second RF transmission lines (20, 30) are otherwise configured as a 3dB coupler.
The coupler as claimed in claim 12 or 13, wherein said line length is 0.627C.
2
A notch filter tunable to a desired fi-equency within a predetermined RF frequency band, comprising a first RF transmission line (20) and a second RF transmission line (30), wherein said first and second RF transmission lines (20, 30) respectively comprise first and second electrically

conductive tracks (21, 31; 21', 31') arranged coaxially about a rotation axis (x-x) in substantial mutually overlapping relationship to provide RF coupling between the first and second RF transmission lines (20, 30) characterized in that each said electrically conductive track (21, 31; 21', 31') has a gap (G1, G2) defining a pair of ports (P1, P2; P3, P4) in the track, one of said ports being connectable to an input or an output of the notch filter and another of said ports being connected to a termination for reflecting RF power, and said first and second electrically conductive tracks (21, 31; 21', 31') being capable of relative rotation about said rotation axis (x-x) to tune the notch filter to the desired frequency.
The notch filter as claimed in claim 15, wherein said first and second tracks (21, 31) are supported in substantially parallel planes orthogonal to said rotation axis and are in radially-overlapping relationship.
The notch filter as claimed in claim 16, wherein said first and second tracks are substantially annular.
The notch filter as claimed in claim 16 or 17, wherein the first track (21) is mounted on a first circuit board (23) and said second track (31) is mounted on a second circuit board (33) which can rotate with respect to the first circuit board (23).
The notch filter as claimed in claim 18, wherein said first RF transmission line (20) comprises a first ground plane (22) provided on one side ofsaid first circuit board (23) and said first track (21) provided

on the opposite side of said first circuit board (23), and said second RP transmission line (30) comprises a second ground plane (32) provided on one side of said second circuit board (33) and said second track (31) provided on the opposite side of said second circuit board (33),
The notch filter as claimed in any one of claims 16 to 19, wherein said first and second tracks (21, 31) are separated by a dielectric spacer (34).
The notch filter as claimed in claim 15, wherein said first and second tracks (21, 31) are arranged in axially-overlapping relationship.
The notch filter as claimed in claim 21, wherein said first and second tracks (21, 31) are substantially cylindrical.
The notch filter as claimed in claim 22, wherein said first and second tracks (21', 31') are respectively provided on the outer and inner surfaces of first and second coaxial dielectric sleeves (35, 36),
The notch filter as claimed in claim 22 or 23, wherein the first and second tracks (21', 31') are separated by a cylindrical dielectric spacer (37).
The notch filter as claimed in claim 15, wherein said first RF transmission line comprises two said electrically-conductive tracks (41, 44), said second RF transmission line comprises two said electrically-conductive tracks (42, 43), said tracks (41, 42, 43, 44) being arranged coaxially around said rotation axis so that the tracks (41,44) of the first

RF transmission line are in substantial radially-overlapping relationship with the tracks (42, 43) of the second RF transmission line to provide coupling between the first and second RF transmission lines, and wherein the tracks (42, 43) of one of said first and second RF transmission lines are electrically and mechanically interconnected and are rotatable about said rotation axis with respect to the tracks (41, 44) of another of said first and second RF transmission lines whereby to tune the filter to the desired fi-equency, and the input to and the output from the filter are connected to respective tracks (41,44) of said another of the RF transmission lines.
The notch filter as claimed in claim 25, wherein said tracks (41, 42, 43, 44) are provided on different circuit boards (Ci, C2, C3, C4) and the input and output terminals for the filter are both provided on the same circuit board (Ci).
The notch filter as claimed in claim 26, wherein the gaps in the tracks [42, 43) of the second RF transmission lines are aligned with respect to each other.
rhe notch filter as claimed in claim 26, wherein the gaps in the tracks [41^ 44) of said first RF transmission line or in the tracks (42, 43) of said second RF transmission line are offset with respect to each other.
rhe notch filter as claimed in claim 26 or 27, wherein the tracks (41, 42, 0,44) all have the same length.

Documents:

853-mas-96 abstract.jpg

853-mas-96 abstract.pdf

853-mas-96 claims.pdf

853-mas-96 correspondence others.pdf

853-mas-96 correspondence po.pdf

853-mas-96 description (complete).pdf

853-mas-96 form-2.pdf

853-mas-96 form-26.pdf

853-mas-96 form-4.pdf

853-mas-96 others.pdf

853-mas-96 petition.pdf


Patent Number 193868
Indian Patent Application Number 853/MAS/1996
PG Journal Number 20/2006
Publication Date 19-May-2006
Grant Date 12-Dec-2005
Date of Filing 21-May-1996
Name of Patentee RACAL-MESL LIMITED
Applicant Address LOCHEND INDUSTRIAL ESTATE, NEWBRIDGE, EDINBURGH EH28 8LP
Inventors:
# Inventor's Name Inventor's Address
1 JOHN WILLINS ARTHUR 85 HILLVIEW ROAD, CORSTORPHINE, EDINBURGH EH12 8QE, SCOTLAND,
PCT International Classification Number H01P1/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 9510829.6 1995-05-22 U.K.