The present invention relates to an antenna interface for a radio receiver.
Already known in the state of the art is an antenna interface for a radio receiver, of
the type comprising a socket, designed to be connected to the receiver, and a plug,
designed to be connected to the antenna.
Such interfaces are typically used for a single-band receiver, i.e. a receiver
capable of transmitting and/or receiving on a single frequency band.
In the case of a dual-band receiver, i.e. a receiver capable of transmitting and/or
receiving on two distinct frequency bands, it is necessary to provide two distinct interface
sockets. However, the use of two sockets is relatively bulky, which is in particular
detrimental to miniaturization of the receiver.
The invention in particular aims to resolve this drawback, by allowing the
connection of an antenna to a dual-band receiver, while limiting the bulk of the connection
means.
To that end, the invention in particular relates to an antenna interface for a radio
receiver, of the type comprising a socket, designed to be connected to the receiver, and a
plug, designed to be connected to the antenna, characterized in that:
- the socket comprises a body and two coaxial cables, each comprising a core, a
braid coaxial to the core, and an electric insulator between the core and the braid so as to
electrically insulate them,
- each coaxial cable extends between a first end connected to a printed circuit
board of the receiver and a second end at which the braid is electrically connected to the
body, and at which the core can be accessed through a respective opening made in the
body of the socket,
- the plug comprises a body and at least two piston contactors, such that, when the
plug and the socket are connected, each contactor is arranged opposite an opening such
that the core of a respective cable is electrically connected to said contactor, and the braid
of each cable is electrically connected to the body of the plug via the body of the socket,
- each piston contactor comprises a stationary portion, to be connected to a printed
circuit board of the antenna, and a moving portion relative to the stationary portion,
including a contact element designed to cooperate with a respective core when the socket
is connected with the plug, and
- the plug comprises a flexible membrane, supporting the contact elements of the
piston contactors.
2
Unlike a traditional antenna interface, the interface according to the invention has
two hot spots (formed by the contactors, to which the cores of the cables are connected)
and a ground reference (formed by the body of the plug, to which the braids of the cables
are connected). In this way, this interface makes it possible to work on two distinct
frequencies, to transmit and/or receive from the station on those two frequency bands.
The interface according to the invention is therefore particularly suitable for connecting an
antenna to a dual-band receiver.
According to the invention, the connection of the antenna to the dual-band receiver
is done using a single interface. However, a single interface is less bulky and expensive
than the two interfaces necessary in the state of the art.
Furthermore, the invention allows the use of a single collinear antenna, which
allows the transmission and/or reception by the receiver on both frequency bands
simultaneously, which was not possible in the state of the art. In fact, in the state of the
art, the use of two sockets involves the use of two respective antennas, each transmitting
in a frequency band, each antenna risking scrambling the other antenna's signal.
Furthermore, it will be noted that the interface according to the invention is suitable
for use in an aggressive environment, for example in a humid environment. In fact, the
membrane performs a sealing function, in particular protecting the connectors and cables
from moisture.
The interface according to the invention may also comprise one or more of the
following features, considered alone or according to all technically possible combinations:
- for each piston contactor, the stationary portion comprises an electrically
insulating hollow cylindrical element, forming a piston body in which the moving part can
move axially, and the contact element of the moving part comprises a first guide portion,
and a second contact portion designed to cooperate with a respective core when the
socket is connected to the plug, and the first guide portion is generally cylindrical, with a
diameter substantially equal to an inner diameter of a hollow cylindrical element, so as to
cooperate without play with an inner wall of said hollow cylindrical element,
- the socket comprises a bottom wall in which the openings are formed, the plug
comprises an end-of-travel stop against which the bottom wall abuts when the socket is
connected to the plug, and the end-of-travel stop being provided such that a free space
remains between the membrane and the bottom wall when the socket is connected with
the plug,
- each piston contactor, in particular the hollow cylindrical element, is sized so as
to minimize the cross-talk between the signals passing through said piston contactors,
preferably for a cross-talk of less than 45 dB,
3
- the socket comprises a first portion, preferably threaded so as to be screwed into
a complementary opening of the receiver or screwed to a locknut, and a second threaded
portion, designed to be screwed in a complementary housing of the plug, the first and
second threaded portions being axially separated by a flange,
- the flange bears, on the side of the first portion, a sealing ring designed to
cooperate with the contour of the complementary opening of the receiver,
- the body of the plug generally has a shape of revolution around an axis, the plug
comprising a knob freely rotating around the axis relative to the body, the knob having a
generally hollow cylindrical shape, inwardly tapped, delimiting the complementary housing
of the second threaded portion of the socket,
- the interface comprises a sealing ring, arranged in the housing of the knob,
between the body and the knob, fa -the socket and the plug comprise complementary means forming a mistakeproofing
device, designed to ensure that the contactors cooperate with a respective core
when the plug and socket are connected.
The invention will be better understood upon reading the following description,
provided solely as an example and done in reference to the appended figures, in which:
- figure 1 is a partial axial side view of an antenna interface according to one
example embodiment of the invention,
- figure 2 is a perspective view of a socket of the antenna interface of figure 1,
- figure 3 is an elevation view of the socket of figure 2,
- figure 4 is a transverse cross-sectional view of the socket figure 1,
- figure 5 is a perspective view of the plug of the interface of figure 1,
- figure 6 is a partial axial cross-sectional view of the plug of figure 5, and
- figure 7 is a transverse cross-sectional view of the plug of figure 5.
Figure 1 shows an antenna interface 8 according to one example embodiment of
the invention. Such an interface 8 is in particular designed to equip a radio receiver, for
example a dual-band tactical radio receiver, to connect a dual-band antenna.
The interface 8 comprises a socket 10, in particular shown in figures 2 to 4, and a
plug 12, in particular shown in figures 5 to 7, designed to cooperate with the socket 10 so
as to form the interface 8 as shown in figure 1.
The socket 10 comprises a body 11, with a general shape of revolution around an
axis X. This body 11 comprises a first portion 14 and a second portion 16, which are
substantially cylindrical, and a flange 18 axially separating the first 14 and second 16
portions.
4
The first portion 14 has a threaded outer surface, designed to be screwed into a
complementary opening of the radio receiver (not shown). The flange 18 then in particular
forms an end-of-travel stop for said screwing.
It will be noted that the threaded outer surface forms particularly compact fastening
means for fastening to the radio receiver, with a reduced axial bulk and that are
sufficiently robust.
Advantageously, a sealing ring 20, visible in figure 3, is borne by the flange 18.
Such a sealing ring 20 is designed to cooperate with the contour of the complementary
opening of the receiver, so as to ensure sealing of the receiver.
Alternatively, the first portion 14 could comprise any other means for fastening to
the radio receiver. For example, said first portion 14 could be threaded only over an area
designed to be screwed into a locknut. The first portion 14 could also not be threaded, but
• designed to be forcibly entered into a complementary opening of the receiver.
The second portion 16 also has a threaded outer surface. Preferably, the second
portion 16 has a diameter larger than the diameter of the first portion 14.
Advantageously, the diameter of the socket 10, in particular the diameter of the
flange 18, is smaller than 2 cm. In other words, the socket 10 is smaller than a socket of a
traditional interface.
The second portion 16 comprises an axial cavity 21, axially delimited by a bottom
wa1l21A.
The socket 10 also comprises at least two distinct coaxial cables 22, designed to
be connected to a radio card of the receiver. In this way, said socket allows direct
mechanical interfacing with said radio card.
A coaxial cable 22 is shown in more detail in figure 1. Traditionally, each coaxial
cable 22 comprises a central conducting core 22A, surrounded by an electrically insulating
material 228, which in turn is surrounded by a conductive braid 22C, positioned coaxially
to the core. The braid 22C is lastly surrounded by an insulating sheath 22D, preferably
fastened to the socket 10.
Each cable 22 comprises a first end, which extends axially outside the socket 10,
beyond the first portion 14, and comprising a traditional connector (not shown) designed
to be connected to the radio card of the receiver. Each cable 22 also comprises a second
end, opposite the first, extending through the socket 10 as far as the bottom wall 21A.
The second end of each cable 22 is connected to the socket 10 using a connecting
element 23, described in reference to figure 1.
The connecting element 23 comprises a first conductive portion 23A in the form of
a sleeve, designed to cooperate with the braid 22C of a respective cable 22, said first
5
portion 23A being housed without play in a through opening 24 of the body 11 of the
socket 10. In this way, the braid 22C is electrically connected to the body 11 by means of
said first portion 23A of the connecting element 23.
The connecting element 23 also comprises a second conductive portion 238,
designed to cooperate with the core 22A of the corresponding cable 22. For example, the
core 22A is inserted into a longitudinal opening of the second portion 238. Preferably, the
second portion 238 comprises a contact plate 25.
The connecting element 23 lastly comprises an electrical insulator 23C, inserted
radially between the first 23A and second 238 conductive portions so as to electrically
insulate them relative to one another.
Advantageously, the O-ring seals 26A, 268 are inserted radially between the first
conductive portion 23A and the insulator 23C, and between the insulator 23C and the
• second conductive portion 238, respectively.
The bottom wall 21A comprises at least two openings 218, through which the
contact plates 25 are respectively accessible.
The plug 12, shown in more detail in figures 5 to 7, also has a general shape of
revolution around an axis X', and comprises a body 27 and a knob 28 freely rotating
around the axis X' relative to the body 27.
The body 27 bears, on the outer surface thereof, means 30 for connecting on an
antenna, in particular a traditional collinear antenna.
The connecting means 30 for example comprise two pairs 31 of fastening fingers
31A, the pairs 31 being arranged diametrically opposite one another. The fastening
fingers 31A of each pair 31 are spaced relative to one another suitably to receive a printed
circuit board of the collinear antenna between those fingers 31A.
Preferably, the fastening fingers 31A are suitable for allowing welding of the
printed circuit board on said fingers 31A. In fact, the welding allows robust and electrically
conductive fastening.
Advantageously, the fastening figures 31A are integral with the body 27 of the plug
12. Alternatively, said fingers 31A may be fastened on the body 27, in particular in the
case where the material from which the fingers 31A are made is better suited to welding
the material from which the body 27 is made.
Furthermore, the body 27 bears an O-ring seal 29 and a flange 30. In this way, the
body 27 is adapted to receive a sleeve of the antenna, the body 27 being fitted into that
sleeve as far as the flange 32, the sealing device 29 then cooperating with the sleeve.
The knob 28 forms a sleeve, with a generally hollow cylindrical shape, delimiting a
housing 33, with a tapped inner wall complementary with the second threaded portion 16
6
•
of the socket 10. In this way, the connection of the socket 10 with the plug 12 is done by
inserting the second threaded portion 16 into the housing 33, then rotating the knob 28, so
as to screw said knob 28 on the second portion 16, until the bottom wall 21 A of the base
10 cooperates with an end-of-travel stop 33A provided in the housing 33.
Preferably, a sealing ring 34 is arranged in the housing 33, between the inner wall
of the housing 33 and the body 27, so as to ensure sealing of the connection between the
socket 10 and the plug 12.
The plug 12 also comprises at least two contactors 36, borne by the body 27 of
said plug 12. When the plug 12 is connected with the socket 10, each contactor 36
cooperates with the plate 25 connected to the core 22A of a respective cable 22,
accessible through the respective opening 218 of the bottom wall 21A. Furthermore, the
braids 22C of the cables 22 cooperate with the body 27 of the plug 12, by means of the
body 11 of the socket. In other words, the contactors 36 form two hot spots of the
antenna, while the body 27 of the plug 12 forms the ground reference.
Preferably, the socket 10 and the plug 12 comprise complementary means 38
forming a mistake-proofing device, designed to ensure that each contactor 36 cooperates
with the respective plate 25 when the plug 12 and the socket 10 are connected.
For example, the means 38 comprise a projection 40 supported by the plug 12
(visible in figure 7), and a complementary cavity 41 formed in the bottom wall 21A of the
socket 10 (visible in figure 4). In this way, the projection 40 is protected by the knob 28,
the height of which provides easy access to that projection 40 for elements of a nature to
damage it. However, the projection may alternatively be supported by the socket 10, and
the complementary cavity formed in the plug 12. Other mistake-proofing means may also
be provided.
Advantageously, at least one contactor 36, preferably each contactor 36, is a
piston contactor comprising a stationary portion 37 and a moving portion 38 relative to the
stationary portion 37, as well as an elastic member 39, for example a spring, arranged
between the stationary portion 37 and the moving portion 38 to return the moving portion
38 toward an idle position.
The stationary portion 37 comprises an electrically insulating hollow cylindrical
element 37A forming a piston body in which the moving portion 38 is designed to move
axially. The stationary portion 38 also comprises a conductive longitudinal element 378,
extending longitudinally between a first end, forming a first seat for the elastic member 39,
and a second end, extending outside the body 27, designed to be connected to the
printed circuit board of the antenna.
7
Preferably, the body 27 bears annular insulating support elements 44, each
annular insulating element 44 bearing the second end of a respective longitudinal
conductive element 37A. These annular elements 44 are designed to keep the second
ends in a specific position, so as to ensure the proper connection of these second ends
with the printed circuit board of the antenna. Furthermore, these annular elements 44, by
maintaining the second ends, participate in the proper robustness of the plug 12. For
example, these insulating annular elements 44 are made from Teflon®.
According to the described embodiment, the moving portion 38 comprises a thrust
element 40, forming a second seat of the elastic member 39, and a contact element 41,
designed to cooperate with a respective plate 25 when the socket 10 is connected with
the plug 12.
The contact element 41 comprises a first guide portion 41A and a second contact
_ portion 41 B.
The first portion 41A has a generally cylindrical shape, with a diameter
substantially equal to an inner diameter of the hollow cylindrical element 37A forming a
piston body, so as to cooperate without play with an inner wall of that hollow cylindrical
element 37A. In this way, this first portion 41A can axially guide the moving portion 38
when it slides in the hollow cylindrical element 37A, by ensuring that that moving portion
38 does not become radially offset. It thus in particular ensures proper alignment between
the thrust element 38 and the contact element 41.
The first portion 41A has a surface, preferably planar, cooperating with the thrust
element 40. To that end, the thrust element 40 has a head 40A, designed to cooperate
with said planar surface. Preferably, the head 40A has a generally rounded shape, so as
to ensure optimal contact with the planar surface of the first portion 41 A.
The second contact portion 41 B forms a head of the contact element 41, designed
to cooperate with a respective plate 25 when the socket 10 is connected with the plug 12.
Preferably, the second contact portion 41 B has a generally rounded shape, so as to
ensure optimal contact with the plate 25.
The plug 12 also comprises a sealing membrane 42, fastened to the body 27 using
a fastening washer 43.
The sealing membrane 42 has two through openings, through which a respective
contact element 41 passes. Thus, the first portion 41A of a contact element 41 is
positioned on one side of the membrane 42, and the second contact portion 41 B is
arranged on the other side of the membrane 42, so as to be accessible to the contact of a
plate 25, the first 41A and second 41 B portions being connected by a connection portion
41 C with a diameter substantially equal to that of the corresponding opening.
8
The membrane 42 is relatively flexible, so as to allow the movement of the moving
portion 38. For example, the membrane 42 is made from an elastomer, preferably
fluorinated silicone.
It will be noted that the fastening washer 43 extends axially beyond the membrane
42, so as to support the end-of-travel stop 33A. Thus, when the socket 10 is connected to
the plug 12, a free space 46 remains between the membrane 42 and the bottom wa1l21A.
This free space 46 in particular allows a free deformation of the membrane 42, so as not
to block any movements of the moving parts 38.
Such a piston contactor 36 can adapt simply and effectively to its environment,
since the position of the moving portion 38 is variable. Thus, the piston contactors in
particular allow flexible and simple fastening of the socket 10 to the plug 12, for example
by taking up play or alignment flaws. Such piston contactors 36 are particularly compact,
which makes it possible to produce a smaller interface.
Furthermore, these piston contactors 36 allow effective separation of the two
bands. Thus, the interface according to the invention in particular allows the radio receiver
to transmit and/or receive on two bands simultaneously.
In fact, each piston contactor is sized so as to minimize coupling between the two
bands, such that the signal on one channel does not disrupt the signal on the other
channel. In other words, each piston contactor is sized so as to minimize the cross-talk
(Le. the parasitic superposition of one signal on another) between signals crossing
through said piston contactors, preferably for a cross-talk of less than 45 dB.
In particular, the dimensions of the electrically insulating hollow cylindrical element
37A are chosen so as to maximize the resistance of that cylindrical element to wave
losses, said resistance being expressed in the form:
60 Dext
R= C·1n--, where
"\IBr Dint
R is the resistance of the insulating element 37A against wave losses,
Bris the relative permittivity of the material from which the insulating element 37A is
made,
Dext is the outer diameter of the insulating element 37A, and
Dint is the inner diameter of the insulating element 37A.
The inner and outer diameters of the insulating element 37A are then generally
determined using simulations making it possible to estimate the optimal values.
Furthermore, the ratio of the diameter of the membrane 42 to the diameter of a
second contact portion 41 B is also estimated so as to optimize the separation between
the two channels.
9
It will be noted that the interface according to the invention has optimal sealing and
good robustness. Such an interface may in particular be used in an aggressive
environment.
Furthermore, the production cost of such an interface is relatively low, in particular
lower than the production cost of the two interfaces of the state of the art needed to
produce a traditional connection of a dual-band radio with an antenna.
It will be noted that the invention is not limited to the embodiment previously
described, but could assume various alternatives without going beyond the scope of the
claims.
In particular, the socket 10 could comprise various fastening means on the
receiver, and the plug 12 could comprise various connecting means on an antenna.
According to another alternative, the plug 12 could comprise two distinct sealing
_ membranes 42, each bearing a respective moving contact element 41.
According to another alternative, the interface could comprise more than two
coaxial cables and corresponding contactors, so as to allow transmission and/or reception
on more than two radiofrequency bands.

We Claim:
1. An antenna interface (8) for a radio receiver, of the type comprising a socket
(10), designed to be connected to the receiver, and a plug (12), designed to be connected
to the antenna, characterized in that:
- the socket (10) comprises a body (11) and two coaxial cables (22), each
comprising a core (22A), a conductive braid (22C) coaxial to the core (22A), and an
electric insulator (22B) between the core (22A) and the braid (22C) so as to electrically
insulate them,
- each coaxial cable (22) extends between a first end connected to a printed circuit
board of the receiver and a second end at which the braid (22C) is electrically connected
to the body (11) of the socket (10), and at which the core (22A) can be accessed through
a respective opening (21 B) made in the body (11) of the socket (10),
- the plug (12) comprises a body (27) and at least two piston contactors (36), such
that, when the plug (12) and the socket (10) are connected, each contactor (36) is
arranged opposite an opening (21 B) such that the core (22A) of a respective cable (22) is
electrically connected to said contactor (36), and the braid (22C) of each cable (22) is
electrically connected to the body (27) of the plug via the body (11) of the socket (10),
- each piston contactor (36) comprises a stationary portion (37), to be connected to
a printed circuit board of the antenna, and a moving portion (38) relative to the stationary
portion (37), including a contact element (41) designed to cooperate with a respective
core (22A) when the socket (10) is connected with the plug (12), and
- the plug (12) comprises a flexible membrane (42), supporting the contact
elements (41) of the piston contactors (36).
2. The antenna interface (8) according to claim 1, wherein, for each piston
contactor:
- the stationary portion (37) comprises an electrically insulating hollow cylindrical
element (37A), forming a piston body in which the moving part (38) can move axially,
- the contact element (41) of the moving part (38) comprises a first guide portion
(41A), and a second contact portion (41B) designed to cooperate with a respective core
(22A) when the socket (10) is connected to the plug (12), and
- the first guide portion (41A) is generally cylindrical, with a diameter substantially
equal to an inner diameter of a hollow cylindrical element (37A) , so as to cooperate
without play with an inner wall of said hollow cylindrical element (37A).
11
3. The interface (8) according to claim 2, wherein:
- the socket (10) comprises a bottom wall (21A) in which the openings (21B) are
formed,
- the plug (12) comprises an end-of-travel stop (33A) against which the bottom wall
(21A) abuts when the socket (10) is connected to the plug (12),
- the end-of-travel stop (33A) being provided such that a free space (46) remains
between the membrane (42) and the bottom wall (21A) when the socket (10) is connected
with the plug (12).
4. The interface (8) according to claim 2 or 3, wherein each piston contactor, in
particular the hollow cylindrical element (37A), is sized so as to minimize the cross-talk
between the signals passing through said piston contactors, preferably for a cross-talk of
less than 45 dB.
5. The antenna interface (8) according to anyone of the preceding claims, wherein
the socket (10) comprises a first portion (14), preferably threaded so as to be screwed into
a complementary opening of the receiver or screwed to a locknut, and a second threaded
portion (16), designed to be screwed in a complementary housing (33) of the plug (12),
the first (14) and second (16) threaded portions being axially separated by a flange (18).
6. The antenna interface (8) according to claim 5, wherein the flange (18) bears,
on the side of the first portion (14), a sealing ring (20) designed to cooperate with the
contour of the complementary opening of the receiver.
7. The antenna interface (8) according to claim 5 or 6, wherein the body (27) of the
plug (12) generally has a shape of revolution around an axis (X'), the plug (12) comprising
a knob (28) freely rotating around the axis (X') relative to the body (27), the knob (28)
having a generally hollow cylindrical shape, inwardly tapped, delimiting the
complementary housing (33) of the second threaded portion (16) of the socket (10).
8. The antenna interface (8) according to claim 7, comprising a sealing ring (34),
arranged in the housing (33) of the knob (28), between the body (27) and the knob (28).
9. The antenna interface (8) according to anyone of the preceding claims, wherein
the socket (10) and the plug (12) comprise complementary means (38) forming a mistake-
12
proofing device, designed to ensure that the contactors (36) cooperate with a respective
(22) core (22A) when the plug (12) and socket (10) are connected.
Date 19 November 2012
To,
The Controller of Patents
The Patent Office at New Delhi
13
iN~
--:-:MALATHI
LAKSHMIKUMARAN
IN/PA-1433
Agent for the Applicant