Note: Descriptions are shown in the official language in which they were submitted.
CA 02803456 2015-05-15
52663-43
FEED NETWORK AND ANTENNA
FIELD OF TECHNOLOGY
[0001]
[0002] The present invention relates to the field of wireless
communication, and in
particular, to a feed network and an antenna.
BACKGROUND
[0003] In wireless communication systems, as more and more voice and
data
information need to be transmitted within a fixed bandwidth, passive
intermodulation (Passive
InterModulation, PIM) becomes an important factor that limits the system
capacity. PIM is a
frequency interference caused by the non-linear characteristic of passive
devices in an
emission system. For example, in systems with great power and multiple
channels, the
nonlinearity of the passive devices brings about higher harmonic waves
relative to a working
frequency. The mixture of the harmonic waves and the working frequency
generates a new
group of frequencies, which is similar to the generation of stray signals when
two or more
frequencies in an active device are mixed in a non-linear device. When a stray
intermodulation signal falls in a receiving band of a base station,
sensitivity of a receiver
decreases, thereby decreasing voice quality or a system carrier-to-interface
ratio (C/I), and
reducing the capacity of a communication system. The PIM is caused by a lot of
factors,
including poor mechanical contact of a feed network.
[0004] A typical communication antenna includes several radiation elements,
a feed
network and a reflector. The function of the feed network is to allocate
signals from a single
connector to all dipole antennas. The feed network usually includes controlled
impedance
transmission lines.
[0005] For feed networks of multiband antennas and smart antennas, a
method for
separating multiple radio frequency transmission channels in the prior art is
shown in FIG. 1.
In this method, a thin metal interlayer 2 and a thin metal interlayer 6 are
used to separate
adjacent radio frequency transmission channel 7 and radio frequency
transmission channel 8.
The metal interlayers are connected through a screw 11 and a screw 12.
1
CA 02803456 2016-04-14
52663-43
[0006] With rapid development of the mobile communication market, the
number of
communication networks increases significantly, and operators have an
increasingly stronger
demand on multiband and multi-system shared antenna, and antenna
miniaturization. The
structure of the feed network of a multiband antenna and smart antenna is
complex, and is
critical to the reliability of the entire antenna. Therefore, a stable and
reliable feed network
with a compact structure is a necessary condition for ensuring multiband and
multi-antenna
performance.
[0007] However, the complex and excessive metal connections in the
feed network in
the prior art easily cause the PIM index of the antenna to be unstable and
unreliable, and
deteriorate the received total wide hand power (RTWP, Received Total Wide band
Power) or
received signal strength indication (RSSI, Received Signal Strength
Indication) of the system.
SUMMARY
[0008] Embodiments of the present invention provide a feed network
and an antenna,
so as to reduce the passive intermodulation interference, and improve the
reliability, stability,
and mobile communication quality of the antenna.
[0009] An embodiment of the present invention provides a feed
network, including: at
least two separate radio frequency transmission channels, wherein the at least
two separate
radio frequency transmission channels are separated by only a single metal
interlayer, one
physical surface of the single metal interlayer is exposed to one of the at
least two separate
radio frequency transmission channels, and the other physical surface of the
metal interlayer is
exposed to another one of the at least two separate radio frequency
transmission channels.
[0009a] Another embodiment provides a feed network, comprising: at
least two
separate radio frequency transmission channels, for transmission of respective
radio frequency
signals along a signal transmission direction; a metal interlayer separating
the at least two
separate radio frequency transmission channels along the signal transmission
direction,
wherein one physical surface of the metal interlayer faces one of the at least
two separate
2
CA 02803456 2016-04-14
52663-43
radio frequency transmission channels, and another physical surface of the
metal interlayer
faces another one of the at least two separate radio frequency transmission
channels.
2a
CA 02803456 2015-05-15
52663-43
[0010] An embodiment of the present invention provides an antenna,
including a feed
network provided in the foregoing embodiment of the present invention.
[0011] In the feed network provided in the embodiment of the present
invention, the
radio frequency transmission channels are separated by a single metal
interlayer without using
any screw or rivet connection. Therefore, passive intermodulation interference
caused by the
metal connection is reduced, which increases the reliability and stability of
the antenna,
enhances the RTWP or RSSI index of the system, and improves the mobile
communication
quality.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] To illustrate the technical solutions in the embodiments of the
present
invention more clearly, the accompanying drawings required for describing the
embodiments
are briefly described in the following. Apparently, the accompanying drawings
in the
following description merely show some embodiments of the present invention,
and persons
of ordinary skill in the art may still derive other drawings from the
accompanying drawings
without creative efforts.
[0013] FIG. 1 is a cross-sectional schematic diagram of a feed
network according to
the prior art;
[0014] FIG. 2 is a three-dimensional schematic diagram of a feed
network structure
according to Embodiment 1 of the present invention;
[0015] FIG. 3 is a schematic diagram of a cross section, orthogonal to a
signal
transmission direction, of the feed network in FIG. 2;
[0016] FIG. 4 is a schematic diagram of a cross section, orthogonal
to a signal
transmission direction, of a feed network according to Embodiment 2 of the
present invention;
[0017] FIG. 5 is a schematic diagram of a cross section, orthogonal
to a signal
transmission direction, of a feed network according to Embodiment 3 of the
present invention;
[0018] FIG. 6 is a schematic diagram of a cross section, orthogonal
to a signal
transmission direction, of a feed network according to Embodiment 4 of the
present invention;
3
CA 02803456 2015-05-15
52663-43
[0019] FIG. 7 is a schematic diagram of a cross section, orthogonal
to a signal
transmission direction, of a feed network according to Embodiment 5 of the
present invention;
and
[0020] FIG. 8 is a schematic assembly diagram of a multiband antenna
according to an
embodiment of the present invention.
DETAILED DESCRIPTION
[0021] The technical solutions in the embodiments of the present
invention are clearly
and completely described in the following with reference to the accompanying
drawings in the
embodiments of the present invention. Apparently, the embodiments to be
described are
merely a part rather than all of the embodiments of the present invention. All
other
embodiments obtained by persons of ordinary skill in the art based on the
embodiments of the
present invention without creative efforts shall fall within the protection
scope of the present
invention.
[0022] Referring to FIG. 2, FIG. 2 is a three-dimensional schematic
diagram of a feed
network structure according to Embodiment 1 of the present invention, and FIG.
3 is a
schematic diagram of a cross section 27, orthogonal to a signal transmission
direction, of the
feed network in FIG. 2.
[0023] In the embodiment shown in FIG. 2 or FIG. 3, a feed network
includes at least
two separate radio frequency transmission channels, which are a radio
frequency transmission
channel 21 and a radio frequency transmission channel 22. Signal lines, such
as a signal line
23, a signal line 24, and a signal line 25, are included in each radio
frequency transmission
channel. At least one radio frequency transmission channel includes at least
two signal lines.
For example, the signal line 23 and the signal line 24 are included in the
radio frequency
transmission channel 21.
[0024] Unlike the prior art in which two metal interlayers are connected
through rivets
or screws, in the embodiment of the present invention, the at least two
separate radio
frequency transmission channels in the feed network are separated by a metal
interlayer 26. In
the embodiment of the present invention, the metal interlayer 26 has a certain
thickness.
4
CA 02803456 2015-05-15
52663-43
Therefore, one physical surface of the metal interlayer is exposed to one of
the at least two
separate radio frequency transmission channels, and the other physical surface
of the metal
interlayer is exposed to another one of the at least two separate radio
frequency transmission
channels. For example, one physical surface 261 of the metal interlayer 26 is
exposed to the
radio frequency transmission channel 21 and the other physical surface 262 is
exposed to the
radio frequency transmission channel 22.
[0025] The metal interlayer separates the radio frequency
transmission without using
any screw or rivet. Therefore, the feed network provided in the embodiment of
the present
invention is devoid of unstable PIM index caused by unreliable connection.
[0026] In consideration of information exchange required between two
adjacent radio
frequency transmission channels or coupling required between two radio
frequency
transmission channels, the exchange or coupling being either in a wireless
manner or a wired
manner, Embodiment 2 of the present invention provides another feed network.
[0027] Referring to FIG. 4, FIG. 4 is a schematic diagram of a cross
section,
orthogonal to a signal transmission direction, of a feed network according to
Embodiment 2 of
the present invention. In this embodiment, a metal interlayer includes several
physically
continuous metal interlayers, where a gap is between the several physically
continuous metal
interlayers. For example, in the feed network shown in FIG. 4, the metal
interlayer 26 shown
in FIG. 2 may be replaced by a metal interlayer 461 and a metal interlayer 462
that are
physically continuous. The term "physically continuous" refers to that,
although the metal
interlayer 26 shown in FIG. 2 may be replaced by the metal interlayer 461 and
the metal
interlayer 462, the metal interlayer 461 and metal interlayer 462 are on the
same plane, and
may be regarded as one metal interlayer if a gap between the interlayers is
filled. Because
there is a gap between the interlayers, a signal line or signal may run
through the gap, thereby
implementing information exchange between two adjacent radio frequency
transmission
channels or coupling between two radio frequency transmission channels.
[0028] The feed network shown in FIG. 4. has an alternative solution,
which is shown
in FIG. 5. In a feed network shown in FIG. 5, a metal interlayer 56 is still
one metal interlayer,
but different from the metal interlayer 26 shown in FIG. 2, the metal
interlayer 56 includes a
5
CA 02803456 2015-05-15
52663-43
hole (indicated by the dashed line in FIG. 5), and a signal line or signal may
also run through
the hole, thereby still implementing information exchange between two adjacent
radio
frequency transmission channels or coupling between two radio frequency
transmission
channels.
[0029] In order to adjust an electrical property of a signal, for example,
to adjust a
resonance frequency, a metal object such as a aluminum alloy object, a zinc
alloy object, or a
copper object may be set in the gap (or hole) of the feed network shown in
FIG. 4 (or FIG. 5);
alternatively, a dielectric part such as FR4 material, microwave sheet
material, PS
(polystyrene), PTFE (polytetrafluoroethylene), PE (polyethylene), PA66
(polyamide) or POM
(polyformaldehyde) is set in the gap (or hole). One part of the metal object
or dielectric part is
in one of the two separate radio frequency transmission channels, and the
other part is in the
other one of the two separate radio frequency transmission channels.
[0030] Taking the feed network shown in FIG. 4 as an example, a metal
object or
dielectric part may be set in the gap, as shown in FIG. 6. In the feed network
shown in FIG. 6,
one part of a metal object or dielectric part 69 is in the radio frequency
transmission channel
21, and the other part is in the radio frequency transmission channel 22.
Setting a metal object
or dielectric part in the hole of the feed network shown in FIG. 5 is similar
to setting a metal
object or dielectric part in the gap of the feed network in FIG. 4, which is
not described in
detail.
[0031] To protect signals in the radio frequency transmission from
interference or
prevent signals in the radio frequency transmission channel from interfering
external signals,
for example, generating electromagnetic leakage, the feed network shown in
FIG. 2 to FIG. 6
may be made into a closed or semi-closed structure. For example, the radio
frequency
transmission channel, except two ends of the signal transmission direction, is
completely
closed or partially closed. As shown in FIG. 7, the radio frequency
transmission channel 21 is
partially closed, and the radio frequency transmission channel 22 is
completely closed.
[0032] In the feed network provided in the embodiment of the present
invention, the
radio frequency transmission channels are separated by the metal interlayer
without using any
screw or rivet connection, thereby reducing passive intermodulation
interference caused by
6
CA 02803456 2015-05-15
52663-43
the metal connection, increasing the reliability and stability of the antenna,
enhancing the
RTWP or RSSI index of the system, and improving the mobile communication
quality.
Meanwhile, because the metal interlayer is a continuous material layer, no
extra size is needed
for connection. Therefore, the feed network provided in the present invention
has a compact
structure, establishes a necessary technical foundation for implementing
miniaturization of
antennas, especially for miniaturization of multiband and multi-system
antennas, reduces the
volume and wind load of the antenna, and lowers the requirement on the
installation
environment of the antenna.
[0033] The present invention also provides a wireless communication
system antenna
using the foregoing feed network, for example, a multiband antenna, a dual-
polarized antenna,
a long term evolution (Long Term Evolution, LTE) antenna, or a smart antenna.
Referring to
FIG 8, FIG. 8 is an assembly schematic view of a multiband antenna according
to an
embodiment of the present invention. To facilitate description, only the parts
related to the
present invention are shown. The antenna includes several radiation/receiving
units 801, a
feed network 803 provided in the embodiment of the present invention, a
calibration network
804 and a dielectric part substrate 805. The radiation/receiving units 801 are
configured to
radiate wireless signals to the outside or receive external wireless signals.
The feed network
803 may be printed on the dielectric part substrate 805 and configured to
allocate signals from
a single connector to each of the radiation/receiving units 801. The
calibration network 804 is
configured to perform real-time calibration on an amplitude and a phase of
each
radiation/receiving unit 801 during operation of the antenna system.
[0034] In the feed network provided in the present invention, the
radio frequency
transmission channels are separated by a metal interlayer without using any
screw or rivet
connection, thereby reducing passive intermodulation interference caused by
the metal
connection, increasing the reliability and stability of the antenna, enhancing
the RTWP or
RSSI index of the system, and improving the mobile communication quality.
Meanwhile,
because the metal interlayer is a continuous material layer, no extra size is
needed for
connection. Therefore, the feed network provided in the present invention has
a compact
structure, establishes a necessary technical foundation for implementing
miniaturization of
antennas, especially for miniaturization of multiband and multi-system
antennas, reduces the
7
CA 02803456 2015-05-15
52663-43
volume and wind load of the antenna, and lowers the requirement on the
installation
environment of the antenna.
[0035] A feed network and an antenna provided in the embodiments of
the present
invention are described in detail. Specific cases are used for illustrating
principles and
embodiments of the present invention. The above descriptions of the
embodiments are merely
provided for better understanding of the method and core ideas of the present
invention.
Meanwhile, persons of ordinary skill in the art may make modifications to the
embodiments
and the application scope according to the idea of the present invention. In
conclusion, the
content of the specification shall not be construed as a limitation to the
present invention.
8
