[0001] The object of the invention is a broadband microstrip antenna with a switchable beam
for the band of 3400-3600 MHz, intended to be used in LTE, 4G and 5G cellular telecommunication
systems, in particular for "small cells" of heterogenic network layer cells by cellular
telecommunication users as well as in other mobile radio communication systems.
[0002] There are known microstrip antennas with a radiator shaped as a rectangle, circle
or triangle. The radiator may be powered by a power network that is positioned on
the same layer as the radiator, on a bottom layer of the radiator or on some other
layer arranged under the layer with the radiator. The radiator may be powered directly
by a microstrip line, by an adaptor or by an electromagnetic coupling through an slot.
Single-layer microstrip antennas powered by a line are characterized by a narrower
operation band. Broadening of the band is possible by means of addition of additional
layers and enlargement of the thickness of the structure. Providing several radiators
of this kind enables forming of an array and increase in the directional gain. Switching
of the beam is possible by orienting the radiators in different directions and selecting
one of the radiators in the array. Other switching methods are based on introduction
of a discrete phase shift on the radiators.
[0003] From
US 2006202892 a switched beam of an antenna arrangement is known. The method of controlling the
antenna arrangement as described therein enables using of the antennas in a predetermined
sequence where suitable time division for each of the antennas is ensured.
[0004] US 2002000941 discloses an antenna arrangement for radiotelephones where the antenna is movable.
Additionally, when in one of its positions, connection of the radiotelephone to the
antenna may be provided in one of two points by means of a press button.
[0005] WO 12048818A1 discloses a solution which enables connection of at least two antennas to a telephone
which has been originally designed for operation with only one antenna. The antenna
is selected by means of a switch.
[0006] JP H01146408 discloses a known antenna assembly comprising microstrip antennas and an antenna
switch for selection of antenna to work over a required band. The solution described
therein is intended for broadening operation frequencies by means of selecting one
of several antennas where each of the antennas is designed for diverse frequency ranges.
[0007] Document
CN 104868233 discloses configurable antennas that are connected, by means of switches, to a signal
input. The solution is intended for emission of a circularly polarized wave.
[0008] Document
KR 20060001210 discloses an antenna switching system and a method for switching them. The system
comprises antennas that may be microstrip antennas, an antenna switching unit and
means for enabling selection of a suitable antenna. The system and method enable selection
of an antenna that ensures the best signal quality.
[0009] Arrays of microstrip antennas with a switched beam are positioned on objects of an
arcuate profile such as for example a surface of a cylinder. This makes it impossible
to use arrays of microstrip antennas with a switched beam on flat surfaces such as
e.g. walls of buildings. An antenna according to the invention may be positioned on
flat surfaces such as walls of buildings or bus stop windshields.
[0010] The invention provides a microstrip antenna comprising two joined dielectric layers,
an upper dielectric layer and a lower dielectric layer, and a shield with slots positioned
therebetween. On the upper dielectric layer radiators are positioned that have a shape
of a planar figure entirely contained on the surface of the upper dielectric layer,
and on the lower dielectric layer a first power network and a second power network
as well as a power line are arranged. The microstrip antenna is characterized in that
the power line is connected to a switching unit and the switching unit is connected
to the first power network and the second power network, that split up into power
strips and power the individual radiators arranged in two arrays. The slots are arranged
so that each one of the slots is positioned between a power strip and the corresponding
radiator.
[0011] Preferably, the switching unit is a three-way switch.
[0012] Preferably, the radiators are of identical shape.
[0013] Preferably, the radiators are of a rectangular shape.
[0014] Preferably, the slots in the shield are of identical shape.
[0015] Preferably, the slots in the shield are of a rectangular shape.
[0016] Preferably, the symmetry centre of each one of the slots corresponds to the symmetry
centre of the corresponding power strips and radiators.
[0017] Preferably, the radiators are arranged in two arrays each with four radiators.
[0018] Preferably, the radiators are positioned at the outer side of the upper dielectric
layer.
[0019] Preferably, the radiators are glued on the upper dielectric layer.
[0020] Preferably, the radiators are formed on the upper dielectric layer as a result of
etching process.
[0021] Preferably, the radiators are formed on the upper dielectric layer as a result of
milling process.
[0022] Preferably, the first power network and the second power network as well as the power
line are arranged on the outer side of the lower dielectric layer.
[0023] Preferably, the first power network and the second power network as well as the power
line are glued to the lower dielectric layer.
[0024] Preferably, the first power network and the second power network as well as the power
line are formed on the lower dielectric layer as a result of etching process.
[0025] Preferably, the upper dielectric layer is made of a ceramic-Teflon® laminate.
[0026] Preferably, the lower dielectric layer is made of an epoxy glass laminate.
[0027] Preferably, impedance of the power line is 50 Ω.
[0028] An antenna according to the invention is a two-layer radiation structure enabling
signal broadband transmission within the band of 3.4-3.6 GHz. Positioning of a shield
between the two layers provides an electric separation between the power line and
the array of radiators. Positioning of e.g. eight radiators in two columns enables
obtaining a broad characteristics in the azimuth plane and narrow characteristics
in the elevation plane. The use of two branches of the power network makes it possible
to switch between the two characteristics in the azimuth plane.
[0029] Two linear arrays of microstrip antennas in the subject solution are positioned parallel
to each other. Only one of the two linear arrays is activated. The inactive linear
array is a passive director and causes a change in the radiation direction. Selection
of the active linear array, and thus the direction of radiation, is effected by means
of a switch provided at the lowest level of the power network.
[0030] The proposed solution enables increasing of the productivity of the base station
by means of selection of one of the two antenna arrays. As a result it is possible
to direct an antenna beam towards an area with greater concentration of users.
[0031] The conductive shield between the two layers alleviates mutual couplings between
the power network and radiators.
[0032] The subject-matter of the invention is shown in the drawing where fig. 1 shows an
antenna in a side view, fig. 2: a view of an upper dielectric layer along with radiators,
fig. 3: a view of a conductive shield with slots, fig. 4: a view of a lower dielectric
layer with a first power network, second power network, a power line and a switching
unit, fig. 5: shows an embodiment of the invention in an axonometric view with radiation
characteristics marked.
[0033] In an embodiment, a microstrip antenna comprises two joined dielectric layers, an
upper dielectric layer 1 arranged over a lower dielectric layer 4, and therebetween
a shield 3 with 8 (eight) rectangular slots 30 is arranged. In one embodiment, slots
30 are etched in the shield 3, in another embodiment, slots 30 are milled in the shield
3. At the outer side 1 of the upper dielectric layer 2 there are 8 (eight) radiators
20 arranged in two arrays each with 4 (four) identical radiators 20, entirely included
on the surface of the upper dielectric layer 2 and being of a shape of a planar figure,
for example a rectangular shape. In an embodiment, radiators 20 are metallized. At
the outer side 5 of the lower dielectric layer 4 a first power network 53 and a second
power network 54 as well as power line 51 are positioned. A conductive, made of copper
in an embodiment, power line 51 is connected to a switching unit 52, which in an embodiment
is a microwave three-way switch. The switching unit 52 is connected to the first power
network 53 and the second power network 54, which enables directing the microwave
power to a selected line array and generating one of two characteristics 6. The power
networks 53 and 54 split up into 8 (eight) power strips 55 and power the individual
radiators 20 arranged in two arrays. The power strips 55 in an embodiment are of a
rectangular shape and the short side of each of the power strips 55 is parallel to
the long side of the corresponding slot 30, i.e. the symmetry centre of each one of
the slots 30 corresponds to the symmetry centre of the corresponding power strips
55 and radiators 20. Each one of the slots 30 is positioned between the power strip
55 and the corresponding radiator 20 to ensure electromagnetic coupling between the
first power network 53, the second power network 54, and the radiators 20.
[0034] In another embodiment the upper dielectric layer 2 is made of a ceramic-Teflon® laminate
of a dielectric permittivity εr =3.5 and thickness h1= 1.524 mm.
[0035] In a further embodiment, the upper dielectric layer 2 and the lower dielectric layer
4 are glued together to provide a glued layer thickness of 0.101 mm. Under the upper
dielectric layer 2 the lower dielectric layer 4 is positioned, the latter being of
a thickness h2=1 mm and made of a laminate of an epoxy glass laminate - FR4 laminate
of a loss angle δ equal to 0.02 and permittivity εr of 4.3.
[0036] In one embodiment, radiators 20 are glued on the upper dielectric layer 2.
[0037] In another embodiment, radiators 20 are formed on the upper dielectric layer 2 as
a result of etching process.
[0038] In another embodiment, radiators 20 are formed on the upper dielectric layer 2 as
a result of milling process.
[0039] In a further embodiment, radiators 20 are of a rectangular shape having dimensions
L=20.5 mm and W=19.4 mm.
[0040] In a further embodiment, slots 30 in the shield 3 are of identical shape. In one
embodiment, slots 30 in the shield 3 are of a rectangular shape.
[0041] In a further embodiment, the first power network 53 and the second power network
54 and the power line 51 are glued to the lower dielectric layer 4.
[0042] In another embodiment, the first power network 53 and the second power network 54
as well as the power line 51 are formed on the lower dielectric layer 4 as a result
of etching process.
[0043] In one embodiment, the upper dielectric layer 2 is made of a ceramic-Teflon® laminate.
[0044] In a further embodiment, the lower dielectric layer 4 is made of an epoxy glass laminate.
[0045] In a further embodiment, the width of the power line 51 is 1.77 mm or, in another
embodiment, has another value corresponding to specific impedance of the line of 50
Ω, i.e. impedance of the power line (51) is 50 Ω. To the power line 51, at the edge
of the antenna, a microwave junction is connected or another microstrip line.
[0046] Embodiments are described herein solely in a form of a non-limiting indications concerning
the invention and they cannot limit in any way the scope of protection as defined
in the claims.
1. A microstrip antenna comprising two joined dielectric layers, an upper dielectric
layer (2) and a lower dielectric layer (4), and a shield (3) with slots (30) positioned
therebetween, where on the upper dielectric layer (2) radiators (20) are positioned
that have a shape of a planar figure entirely contained on the surface of the upper
dielectric layer (2), while on the lower dielectric layer (4) a first power network
(53) and a second power network (54) as well as a power line (51) are arranged, characterized in that the power line (51) is connected to a switching unit (52), and the switching unit
(52) is connected to the first power network (53) and the second power network (54),
that split up into power strips (55) and power the individual radiators (20) arranged
in two arrays, where the slots (30) are arranged so that each one of the slots (30)
is positioned between a power strip (55) and the corresponding radiator (20).
2. Antenna according to claim 1, characterized in that the switching unit (52) is a three-way switch.
3. Antenna according to claim 1, characterized in that radiators (20) are of identical and/or a rectangular shape.
4. Antenna according to claim 1, characterized in that the slots (30) in the shield (3) are of identical and/or a rectangular shape.
5. Antenna according to any of the above claims 1-4, characterized in that the symmetry centre of each one of the slots (30) corresponds to the symmetry centre
of the corresponding power strips (55) and radiators (20).
6. Antenna according to claim 1, characterized in that radiators (20) are arranged in two arrays each with four radiators (20).
7. Antenna according to claim 1, characterized in that radiators (20) are positioned at the outer side (1) of the upper dielectric layer
(2).
8. Antenna according to claim 7, characterized in that radiators (20) are glued on the upper dielectric layer (2).
9. Antenna according to claim 7, characterized in that radiators (20) are formed on the upper dielectric layer (2) as a result of etching
and/or milling process.
10. Antenna according to claim 1, characterized in that the first power network (53) and the second power network (54) and the power line
(51) are arranged on the outer side (5) of the lower dielectric layer (4).
11. Antenna according to claim 10, characterized in that the first power network (53) and the second power network (54) and the power line
(51) are glued to the lower dielectric layer (4).
12. Antenna according to claim 10, characterized in that the first power network (53) and the second power network (54) and the power line
(51) are formed on the lower dielectric layer (4) as a result of etching process.
13. Antenna according to claim 1, characterized in that the upper dielectric layer (2) is made of a ceramic-Teflon® laminate.
14. Antenna according to claim 1, characterized in that the lower dielectric layer (4) is made of an epoxy glass laminate.
15. Antenna according to claim 1, characterized in that impedance of the power line (51) is 50 Ω.