Field of the invention
[0001] The invention relates to a coaxial RF connector system which can be connected or
disconnected under high power load.
Description of the related art
[0002] A coaxial RF connector system is disclosed in
EP 3 300 535 A1. This connector system can couple comparatively high RF power up to a few Kilowatts.
For connecting and/or disconnecting, the power must be switched off. If these connectors
are connected or disconnected under load, arcing may occur which may lead to a severe
damage of the connectors. Further, there are no precautions to avoid an early connection
between the center conductors during connecting or a late disconnection of the center
conductors while disconnecting, specifically due to arcing. A center connector contact
without shield or ground contact may incur a safety risk, as an ungrounded section
of the conductor system may be at a high voltage. This may be harmful for persons
operating the connectors.
Summary of the invention
[0003] The problem to be solved by the invention is to provide an RF connector system which
is capable of transferring high power RF signals in the range of several Kilowatts
and in a broad frequency range between 1 Megahertz and multiple GHZ, but not limited
to that range. This coaxial connector system should be connectable and/or disconnectable
when an RF signal is applied on one side, which may be either the male or the female
connector. This connection/disconnection must be electrically safe and must not damage
any of the connectors.
[0004] Solutions of the problem are described in the independent claims. The dependent claims
relate to further improvements of the invention.
[0005] In an embodiment, a coaxial connector system may include a main body and a load connector.
The main body may have a cylindrical bore, the main body may further hold a cylindrical
main center conductor. This forms a coaxial system, where the main body is the outer
conductor. This coaxial system may have a specific characteristic impedance, e.g.,
50 Ohm. The main center conductor has at one end a main contact area, which is configured
to provide a contact with a center conductor of the load connector. This main contact
area may be within the cylindrical bore of the main body and recessed for a recess
distance from a first end end of the cylindrical bore of the main body, which may
be opposing to the main center conductor. The recess distance may be such, that a
contact can only be established when the inner conductor protrudes into the cylindrical
bore of the main body for a minimum protrusion length which may be 200%, 100%, 50%
or 10% of the diameter of the cylindrical main center conductor. This may form an
arcing space between the main contact area and the first end of the cylindrical bore
of the main body. As such, the arcing area is located deeply in the cylindrical bore
of the main body. Further, the contact sleeve may have an inner length which is larger
than the recess distance. Such a recess results in a larger air gap. Further, the
main body and/or the contact sleeve may act as circular waveguides which may have
a high attenuation for electromagnetic waves coming from the center conductor. This
increases attenuation in a disconnected state. Further, this offers an improved protection
against touching the center conductor.
[0006] In an embodiment, an insulating tube may be held within the cylindrical bore of the
main body. The insulating tube may further hold the cylindrical main center conductor.
The insulating tube may include any suitable insulating or dielectric material, e.g.,
PTFE or any other suitable material. It may be beneficial to use high temperature-resistant
materials, like polyimide or others, as these may better withstand high temperatures
which may occur during arcing. The insulating tube may fit exactly between the main
center conductor and the main body, such that there is no or only a marginal air gap.
Specifically, an air gap between the cylindrical bore of the main body and the insulating
tube may be less than 50% or 10% or 5% or 2% or 1% of the diameter of the cylindrical
main center conductor. Alternatively, the air gap may be less than 1mm or 0.2mm or
0.1mm. This may avoid partial discharges under high voltages. The main contact area
is recessed for a recess distance from a first end of the tube and within the tube.
[0007] In an embodiment, the outer conductor may include an outer conductor connector which
may further include at least one contact spring. The a) outer conductor connector
or b) a contact area between the outer conductor connector and either the main body
or a contact sleeve may be axially distant from the main contact area. This may result
in a larger air gap compared to standard connectors, without such an axial spacing.
[0008] The load connector may also include a coaxial conductor system with an outer conductor
and an inner conductor, which may also be spaced by a spacing tube. The inner conductor
has a center contact pin or is attached to a center contact pin which is configured
to enter into contact with the main center conductor. For this purpose, the center
contact pin is configured to protrude into the insulating tube, until it reaches the
recessed end of the main center conductor and establishes a contact therewith at the
main contact area. The main contact area of the main center conductor and/or the center
contact pin may include a suitable contact material which further may withstand high
temperatures and/or arcing. This may be a silver alloy including nickel and/or cadmium,
or any other heat-resistant material, like tungsten.
[0009] The center contact pin may be loaded by a spring to ensure a proper contact force
between the contact pin and the main center conductor. Further, there may be a limit
stop to prevent a too far extension of the contact pin. For connecting the load connector,
this is simply plugged into the main body such that the center contact pin protrudes
into the insulating tube and enters into contact with the main center conductor. The
center contact pin may have a spring in an axial direction, such that it contacts
the center conductor in an axial direction. This allows to form the center contact
pin cylindrically, which may reduce or even eliminate any air gap to the insulating
tube, such that partial discharges are minimized, and the lifetime is significantly
increased.
[0010] The outer conductor of the load connector may have contact springs or spring elements
to provide a good contact to the main body or a contact sleeve, which may be part
of an outer flange which further may be attached to the main body.
[0011] In an embodiment, the main body may include a contact sleeve, which is configured
to establish an electrical contact to the outer conductor of the load connector (by
means of the outer conductor connector) and which may improve security. When connecting
the load connector to the main body, the outer conductors may be connected first and
when disconnecting, the outer conductors are connected last. In an embodiment, the
length of the contact sleeve is configured such, that the outer conductor of the load
connector is in contact with the contact sleeve as long as the center contact pin
reaches at least partially into the insulating tube. The contact sleeve may be configured
to contact the outer conductor of the load connector and it may have a length such
that when the load connector is being connected to the main body, the outer conductor
is contacted before the main center conductor establishes a contact.
[0012] When disconnecting the connector under load, e.g., when a power source is connected
to either side or both sides, arcing may occur when the center contact pin is removed
from the main center conductor. The arc generates hot ionized gases which are kept
within the insulating tube. For this purpose, the recess distance of the insulating
tube must be long enough to provide a sufficient space for hot gases. Further, the
insulating tube may extend with its first end over the main body, such that no arc
can establish from the hot gases of the interior of the tube to its outside and to
the main body. To reduce arcing, it may be desired to cool down the hot gases as much
as possible. For this purpose, the cylindrical main center conductor may be a solid
body of metal providing a high thermal conductivity and a high thermal capacitance.
Furthermore, the center contact pin may also include a solid piece of metal. Further,
it is preferred if the main center conductor has a certain minimum length which enables
it to dissipate heat through the insulating tube to the main body. As the insulating
tube, which may include an electrically insulating or dielectric material, is with
a high probability therefore thermal insulating, it is difficult to transfer heat
from the main center conductor to the main body. Accordingly, a long main center conductor
may be used.
[0013] In an embodiment, the main center conductor is connected to a source connector inner
conductor which is coaxial to a source connector outer conductor. The source connector
outer conductor may form a circular waveguide and exceeds the length of the source
connector inner conductor preferably of at least one half or one wavelength of a signal
transmitted.
[0014] In an embodiment, a pneumatic actuator is provided. The center contact pin may be
replaced by a pneumatic piston operated center contact pin. It may include a pneumatic
piston section and a contact pin section which may be a single (monolithic) part or
separated parts, e.g., having a contact section and a piston rod section. The pneumatic
piston operated center contact pin may be held in an essentially coaxial tube forming
the center conductor. An outer conductor may be coaxially surrounding the center conductor.
The outer conductor may be slidable in a contact sleeve or fixedly mounted to the
main body.
[0015] There may be a contact sleeve to provide a good electrical contact between the center
contact pin and the center conductor.
[0016] At least one piston is part of or mounted to the center contact pin and seals against
the interior of center conductor. The pistons can move along a common center axis
of the center contact pin and the center conductor. The pistons may be operated by
gas pressure provided through first and second gas ducts. The gas ducts may include
dielectric insulating material and may further hold the center conductor within the
outer conductor. Although one piston may be sufficient, two pistons are shown which
provide a better support of the contact pin. The gas may be any type of gas. Air and
nitrogen are well suited. A gas like argon may be used, as this may also help to quench
or extinguish any arc at the electrical contact.
[0017] To close the electrical connection, the center conductor may be moved to a close
position by providing gas pressure through the second gas ducts, filling first chambers,
and pressing the pistons to a first side. For opening the electrical connection, the
center conductor may be moved to an opposing side by providing gas pressure through
the first gas ducts, filling second chambers, and pressing the pistons to the opposing
side.
[0018] There may be a mechanical lock including at least one locking lever. The at least
one locking lever may snap into a recess or groove in the pneumatic piston operated
center contact pin, when the contact pin is in a closed position (first side). It
may also lock into a second recess or groove in the pneumatic piston operated center
contact pin, when the contact pin is in an open position (opposing side). The at least
one locking lever may include a spring or other elastic element to hold the locking
lever in a position engaged with the contact pin. There may be at least one release
pin which may press on the at least one locking lever to release the locking lever
and therefore to allow the contact pin to move. The release pin may be operated manually
through a flexible outer conductor by pressing on the outer conductor.
Description of Drawings
[0019] In the following the invention will be described by way of example, without limitation
of the general inventive concept, on examples of embodiment with reference to the
drawings.
Figure 1 shows a connector system.
Figure 2 shows a schematic with dimensions.
Figure 3 shows arcing paths.
Figure 4 shows an embodiment with a pneumatic actuator.
Figure 5 shows a front view of the pneumatic actuator.
[0020] In Figure 1, a connector system 100 is shown. It includes a main body 110 with a
coaxial conductor structure and an arcing space. It is contacted by a source connector
200 and a removable load connector 300, which may be disconnected while power is provided
at the source connector and/or power is provided at the load connector.
[0021] In an embodiment, the connector system includes a main body 110 holding an insulating
tube 120. The main body 110 may include an electrically conductive material, like
a metal which may be copper, brass, or aluminum. It may further be coated or galvanized
by a highly conductive material e.g., silver, gold, or an alloy including one of these.
The insulating tube may include a dielectric material which is suitable for radio
frequencies. This may for example be PTFE. In an embodiment, the insulating tube includes
a heat resistant dielectric material like polyimide which can withstand higher temperatures
which are generated by arcs during connecting and/or disconnecting of the connector
system. Within the insulating tube 120 is a main center conductor 130. This may include
a conductive material, like copper, brass, aluminum, or any other suitable material,
which may be coated or galvanized with a highly conductive material like e.g., silver,
gold, or an alloy including one of these. The main center conductor 130 may include
a solid cylinder of a material or metal, which may provide a comparatively high thermal
capacity to absorb heat which is developed by arcs. It may further have a certain
minimum length to provide a larger outer surface area which allows to dissipate heat
through the insulating tube 120 to the main body 110 which may be of a thermally conductive
material. The main center conductor 130 may be held in place by a dielectric support
134.
[0022] The main center conductor has a main contact area 132 at one end. This main contact
area 132 may include or may be coated with a specific heat-resistant and/or arc-resistant
material. Such a material may e.g., be tungsten or a silver alloy further including
e.g., nickel and/or cadmium. The main contact area may be a planar surface, or it
may be a surface with a large radius of 10 cm or more. The main contact area 132 is
recessed within the insulating tube 120 at a distance 182 to form an arcing space
180 within the insulating tube 120. Within this arcing space, arcs may develop when
opening or closing the electrical contact when RF-power is applied to the connector
system. This arcing space 180 is within the insulating tube such that no arc may develop
from a center conductor to an outer conductor due to hot ionized gases.
[0023] The main contact area 132 is contacted by a center contact pin 340 which may be part
of the load connector 340. This pin 340 may have a pin body 342 which may be held
by a guide sleeve 346 and further has a center contact area 344 at its tip, which
is configured to contact the main contact area 132. For providing a defined contact
force, a spring 348 may be provided which may press the center contact pin 340 against
the main center conductor 130. The center contact pin 340 may also include a heat-resistant
and/or arc-resistant material.
[0024] The center contact pin 340 may have a depth stop or limit stop 349, such that it
may only extend a few millimeters from the guide sleeve 346, which may be sufficient
for providing an electrical contact when properly inserted into the insulating tube.
The depth stop may prevent a long arc when disconnecting the connectors due to a long
extension of the center contact pin. The center contact pin may have a cylindrical
shape or outer contour, such that any air gap to the insulating tube may be reduced
or eliminated, such that partial discharges are minimized, and the lifetime is significantly
increased.
[0025] The load connector 300 may include a center conductor 350, which may contact the
center contact pin 340. It may further include an outer conductor 360 spaced from
the center conductor 350 by a spacing tube 364. The outer conductor 360 may have an
outer conductor connector 362 which may include a plurality of contact springs to
contact a contact sleeve 175. The outer conductor may include a spacer 366 which may
be a ring of an insulating material, e.g., a plastic material which may easily slide
along the contact sleeve 175. The contact sleeve 175 may be one part with the main
body 110 or it may be attached to the main body 110, e.g., by an outer flange 170.
The outer flange 170 may be screwed to the main body by screws 190. The contact sleeve
175 may be configured to contact the outer conductor 360 of the load connector 300
when the center contact pin 340 protrudes at least partially into the insulating tube
120. Further, the contact sleeve 175 may have an inner length 177 which is larger
than the recess distance 182.
[0026] A source connector 200 may include an inner conductor 210 and an outer conductor
220. There may be an inner connector contact 230. The outer conductor 220 may be extended
in its length as shown or longer. In the case, the source connector 200 is disconnected
and power is fed from the load connector 300 (in reverse direction), this may be radiated
by a normal RF connector as source connector. Such radiation og high power may be
harmful to persons handling the device. The extended length outer conductor acts as
a circular waveguide, in which TEM waves coming from the load connector cannot propagate
and therefore blocks or at least significantly reduces reverse RF power from the load
connector. The source connector outer conductor (220) may exceed in its lenght the
source connector inner conductor (210) preferably of at least one half or one wavelength
of a signal transmitted. This solution may also be used alone, without the connector
system 100, but significantly reduces the safety of the connector system 100, when
combined with it.
[0027] In Figure 2 a schematic with dimensions is shown. As mentioned above, the inner length
177 of the contact sleeve 175 may be larger than the recess distance 182. Here, the
inner length 177 is the length, which may be used to establish a contact between the
outer conductor 360 and the contact sleeve 175. This relationship of lengths may ensure,
that the outer conductor 360 is in contact with the contact sleeve 175 before it enters
the insulating tube 120.
[0028] Figure 3 shows arcing paths. The shortest arcing path 401 in disconnected or OFF
state is from the main center conductor along the insulating tube 120 to the main
body or a part thereof outside the insulating tube 120. There may be a connector arcing
path 402 between the main center conductor 130 and the center contact pin 340. If
the connector arcing path is longer than the shortest arcing path, with a high probability,
an arc will first establish on the shortest arcing path. Therefore, the load connector
is safe, even without a connection of the outer conductor 360 to the contact sleeve
175 if it is distant enough. Before coming too close, an outer conductor connection
is established to provide a proper current return path and to avoid high RF voltage
at the outside of the load connector assembly and parts connected thereto.
[0029] Figure 4 shows an embodiment having a pneumatic actuator in a side cut view. Here,
the center contact pin 340 of figure 1 is replaced by a pneumatic piston operated
center contact pin 520. It may include a pneumatic piston section and a contact pin
section which may be a single (monolithic) part or separated parts, e.g., having a
contact section 520 and a piston rod section 526. The contact pin section may further
have a contact element 528, which may include a contact material with low resistive
contact properties and/or arc proofness. The pneumatic piston operated center contact
pin 520 may be held in an essentially coaxial tube forming the center conductor 530.An
outer conductor 510 is coaxially surrounding the center conductor 530. The outer conductor
may be slidable in a contact sleeve 175 or fixedly mounted to the main body.
[0030] There may be a contact sleeve 532 to provide a good electrical contact between the
center contact pin 520 and the center conductor 530.
[0031] At least one piston 522, 524 is part of or mounted to the center contact pin 520
and seals against the interior of center conductor 530. The pistons can move along
a common center axis 580 of the center contact pin 520 and the center conductor 530.
The pistons are operated by gas pressure provided through first and second gas ducts
542, 543, 544, 545. The gas ducts may include dielectric insulating material and may
further hold the center conductor 530 within the outer conductor 510. Although one
piston may be sufficient, two pistons are shown which provide a better support of
the contact pin. The gas may be any type of gas. Air and nitrogen are well suited.
An inert gas like argon may be used, as this may also help to quench or extinguish
any arc at the electrical contact. Such an inert gas may also be provided by an inert
gas duct 590.
[0032] To close the electrical connection, the center conductor 530 may be moved to left
side in figure 4 by providing gas pressure through the second gas ducts 544, 545,
filling first chambers 552, 554 and pressing the pistons 522, 524 to the left. For
opening the electrical connection, the center conductor 530 may be moved to right
side in figure 4 by providing gas pressure through the first gas ducts 542, 543, filling
second chambers 553, 555 and pressing the pistons 522, 524 to the right.
[0033] There may be a mechanical lock including at least one locking lever 562. The at least
one locking lever 562 may snap into a recess or groove in the pneumatic piston operated
center contact pin 520, when the contact pin is in a closed position (left side).
It may also lock into a second recess or groove in the pneumatic piston operated center
contact pin 520, when the contact pin is in an open position (right side). The at
least one locking lever may include a spring or other elastic element to hold the
locking lever in a position engaged with the contact pin. There may be at least one
release pin 564 which may press on the at least one locking lever to release the locking
lever and therefore to allow the contact pin to move. The release pin may be operated
manually through a flexible outer conductor 510 by pressing on the outer conductor
510.
[0034] Figure 5 shows the previous embodiment in a front view.
List of reference numerals
[0035]
- 100
- connector system
- 110
- main body
- 120
- insulating tubes
- 122
- first end of tube
- 130
- main center conductor
- 132
- main contact area
- 134
- dielectric support
- 170
- outer flange
- 175
- contact sleeve
- 177
- inner length of contact sleeve
- 180
- arcing space
- 182
- recess distance
- 190
- mounting screw
- 200
- source connector
- 210
- source connector inner conductor
- 220
- source connector outer conductor
- 230
- source contact
- 300
- load connector
- 340
- center contact pin
- 342
- pin body
- 344
- center contact area
- 346
- guide sleeve
- 348
- spring
- 349
- limit stop
- 350
- center conductor
- 360
- outer conductor
- 362
- outer conductor connector
- 364
- spacing tube
- 366
- spacer
- 401
- shortest disconnected arcing path
- 402
- connector arcing path to load connector
- 500
- pneumatic actuator
- 510
- outer conductor
- 520
- pneumatic piston operated center contact pin
- 522,524
- piston
- 526
- piston rod
- 528
- contact element
- 530
- center conductor
- 532
- contact sleeve
- 542, 543
- first gas ducts
- 544, 545
- second gas ducts
- 552, 554
- first chambers
- 553, 555
- second chambers
- 562
- locking lever
- 564
- release pin
- 580
- center axis
- 590
- inert gas duct
1. A coaxial connector system (100) including a main body (110) and a load connector
(300),
the main body (110) having a cylindrical bore, the main body (110) holding a cylindrical
main center conductor (130) having at one end a main contact area (132) being recessed
for a recess distance within the cylindrical bore and forming an arcing space (180)
between the main contact area (132) and a first end (122) of the cylindrical bore,
the load connector (300) having an outer conductor (360) and an inner conductor (350)
spaced from each other, the inner conductor (350) having a center contact pin (340)
which is configured to protrude into the cylindrical bore of the main body (110) opposing
to the main center conductor and to establish a contact with the main center conductor
(130) at the main contact area (132).
2. Coaxial connector system (100) according to claim 1,
characterized in, that
the cylindrical bore of the main body (110) holds an insulating tube (120) wherein
the insulating tube (120) may hold the cylindrical main center conductor (130).
3. Coaxial connector system (100) according to the previous claim, characterized in, that
an air gap between the cylindrical bore of the main body (110) and the insulating
tube (120) is less than 50% or 10% or 5% or 2% or 1% of the diameter of the cylindrical
main center conductor (130).
4. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the main body (110) comprises a contact sleeve (175) which is configured to contact
the outer conductor (360) of the load connector (300) and which may have a length
such that when the load connector (300) is being connected to the main body (110),
the outer conductor (360) is contacted before the main center conductor (130) establishes
a contact.
5. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the main contact area (132) is recessed within the cylindrical bore of the main body
(110) such that a contact can only be established when the inner conductor (350) protrudes
into the cylindrical bore of the main body (110) for a minimum protrusion length which
may be 200%, 100%, 50% or 10% of the diameter of the cylindrical main center conductor
(130).
6. Coaxial connector system (100) according to the previous claim,
characterized in, that
the contact sleeve (175) has an inner length (177) which is larger than the recess
distance (182), and/or
the contact sleeve (175) is configured to contact the outer conductor (360) of the
load connector (300) when the center contact pin (340) protrudes at least partially
into the insulating tube (120) and/or the cylindrical bore of the main body (110).
7. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the recess distance (182) is larger than the diameter of the main center conductor
(130).
8. Coaxial connector system (100) according to any of the previous claims,
characterized in, that
the outer conductor (360) comprises an outer conductor connector (362) which may further
include at least one contact spring and wherein
a) the outer conductor connector (362) or
b) a contact area between the outer conductor connector (362) and either the main
body (110) or a contact sleeve (175) is axially distant from the main contact area
(132).
9. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the insulating tube (120) comprises a heat resistant dielectric material.
10. Coaxial connector system (100) according to any of the previous claims,
characterized in, that
the center contact pin (340) is loaded by a spring (348) which may be oriented in
an axial direction and/or
the center contact pin (340) is configured to contact cylindrical main center conductor
(130) at the main contact area (132) in an axial direction and/or
the center contact pin (340) comprises a limit stop (349) and/or
the center contact pin (340) includes a heat-resistant and/or arc-resistant material
and/or
the center contact pin (340) has a cylindrical shape or contour.
11. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the main contact area (132) of the main center conductor (130) includes a heat-resistant
and/or arc-resistant material.
12. Coaxial connector system (100) according to any of the previous claims, characterized in, that
the main center conductor (130) includes a solid body of metal.
13. Coaxial connector system (100) according to any of the previous claims, characterized in, that
a pneumatic piston operated center contact pin (520) is provided, which comprises
a piston rod (526) with at least one piston (522, 524), guided in a hollow center
conductor (530).
14. Coaxial connector system (100) according to the previous claim, characterized in, that
at least one gas duct (542, 543, 544, 545) is provided to feed gas into the center
conductor (530) and to move the at least one piston.
15. Coaxial connector system (100) according to the previous claim, characterized in, that
the main center conductor (130) is connected to a source connector inner conductor
(210) which is coaxial to a source connector outer conductor (220), wherein the source
connector outer conductor (220) forms a circular waveguide and exceeds in its length
the source connector inner conductor (210) preferably of at least one half or one
wavelength of a signal transmitted.