Antenna switching system

1. Field of the Invention

The present disclosure relates to an antenna switching system that utilizes a novel circuit to meet the requirements of a single beam operation and a combined beam operation for a smart antenna.

2. Description of Related Art

The smart antenna plays an important role in the existing and next-generation wireless communication systems, which has the advantages of improving the efficiency of spectrum resources, system capacity, and communication quality. One of main functions of the smart antenna technology is beamforming. A beamforming technology is for creating the radiation pattern for a beam to direct in a particular direction, and includes a switched beamforming technique and an adaptive beamforming technique.

The switched beamforming technique utilizes multiple beams that point in different directions so as to cover the entire communication area. When a user device, such as a wireless mobile device, enters one Beam Footprint covered by a specific beam, the smart antenna may be switched to the specific beam, which maximizes the received signal strength indication (RSSI) and the signal to noise ratio (SNR). Since the switched beamforming technique is simple and does not require complicated calculations, the smart antenna with switched beamforming technique is still one of the most widely used types in the field.

FIG. 1 shows a schematic diagram of a conventional switched beamforming circuit. As shown in the figure, six diode switching circuits are provided, and each Horizontal-polarized antenna sector is controlled by one diode switching circuit for turning the RF signal on or off. Each diode switching circuit consists of a bias circuit, a diode, a control circuit, and a matching network (MN). Theoretically, the impedance matching network (MN1, MN2) can achieve a 50-ohm matching between radio frequency circuit RF1 and one of the antenna sectors when any one of the diode switching circuits is turned on to form a single beam.

When two adjacent diode switching circuits need to be turned on to form a combined beam, the parallel impedance would become 50-ohm//50-ohm=25-ohm, therefore, the impedance matching would not able to be achieved between the parallel impedance and the impedance matching network MN1.

Moreover, when the adjacent two diode switching circuits are turned on to form a combined beam, causing poor isolation between two antenna sectors since the impedances thereof are not matched, and the isolation is not good between the adjacent two diode switching circuits, such that the efficiency of the combined beam would be low.

The bias voltage for the diode is generally about 3.3V. Therefore, in order to provide a voltage to reach a reverse bias for the diode to turn off the diode, the control circuit must able to provide the reverse bias voltage greater than 3.3V which is generally about 5V or 12V. In order to supply voltages greater than 5V, the system mainboard may require a DC to DC converter, which may increase the costs.

Therefore, a novel antenna switching system is needed to meet the requirements of the single beam and the combined beam required for a smart antenna, while achieving low costs and low operation voltage.

According to an embodiment of the present disclosure, there is provided an antenna switching system including a first radio frequency (RF) circuit for transceiving signals, a first switch circuit, and a plurality of first antennas. The first switch circuit includes a master switch, a plurality of power dividers and a plurality of switches. The master switch includes a first common port, a plurality of power divider (PD) ports and a plurality of first ports. The first common port is electrically connected to the first RF circuit, and a number of the plurality of PD ports is equal to a number of the plurality of first ports and is an integer equals to or larger than 3. The plurality of power dividers each includes a second common port, a second port and a third port. A number of the plurality of power dividers is equal to the number of the plurality of PD ports, and the second common ports of the plurality of power dividers are electrically connected to the plurality of PD ports, respectively. The plurality of switches, each includes a third common port, a fourth port, a fifth port and a sixth port. A number of the plurality of switches is equal to the number of the plurality of first ports, the fourth ports of the plurality of switches are electrically connected to the plurality of first ports, respectively, the fifth ports of the plurality of switches are electrically connected to the second ports of the plurality of power dividers, respectively, the sixth ports of the plurality of switches are electrically connected to the third ports of the plurality of power dividers, respectively, and the fifth port and the sixth port of each of the plurality of switches are electrically connected to different ones of the plurality of power dividers, respectively. The plurality of first antennas are electrically connected to the third common ports of the plurality of switches, respectively, and a number of the plurality of first antennas is equals to the number of the plurality of switches. When the first common port is switched to one of the plurality PD ports electrically connected to a selected one of the plurality of power dividers, the fifth port electrically connected to the selected one of the plurality of power dividers is switched to the third common port, and the sixth port electrically connected to the selected one of the plurality of power dividers is switched to the third common port.

According to another embodiment of the present disclosure, there is provided an antenna switching system including a radio frequency (RF) circuit for transceiving signals, N antennas, a master switch, N switches, and N power dividers. The master switch is electrically connected to the RF circuit. An i th switch of N switches is electrically connected between the master switch and a i th antenna of the N antennas, where i is an integer from 1 to N, and N is an integer equal to or larger than 3. A j th power divider of the N power dividers is electrically connected between the master switch and a j th switch of the N switches, and between the master switch and a (j+1) th switch of the N switches, where j is an integer from 1 to N−1, and a N th power divider of the N power dividers is electrically connected between the master switch and a N th switch, and between the master switch and a 1 st switch of the N switches. The signals are transmitted by one of the N antennas, or the signals are transmitted by the antennas of the N antennas corresponding to the switches connected to one of the N power dividers.

According to yet another embodiment of the present disclosure, there is provided an antenna switching system including a radio frequency (RF) circuit for transceiving signals and a switch circuit. The switch circuit includes a master switch, a first switch, a second switch, a third switch, a first power divider (PD) and a second power divider (PD). The master switch includes a first common port, a first power divider (PD) port and a second PD port, a first port, a second port, and a third port, and the first common port is electrically connected to the first RF circuit. The first switch is electrically connected to a first antenna and the master switch. The second switch is electrically connected to a second antenna and the master switch. The third switch is electrically connected to a third antenna and the master switch. The first power divider (PD) and a second power divider (PD) each includes a second common port, a fourth port and a fifth port. The second common ports of the first PD and the second PD are electrically connected to the first PD port and the second PD port, respectively, the fourth ports of the first PD and the second PD are electrically connected to the first switch and the second switch, respectively, and the fifth ports of the first PD and the second PD are electrically connected to the second switch and the third switch, respectively. When the first common port is switched to the first PD port, a radiation pattern formed by the first antenna and the second antenna is toward to a first direction, and when the first common port is switched to the second PD port, a radiation pattern formed by the second antenna and the third antenna is toward to a second direction.

The features, functions, and advantages can be achieved independently in various embodiments of the present disclosure or may be combined in yet other embodiments in which further details can be seen with reference to the following description and drawings.

The novel features believed characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as modes of use, further objectives and advantages thereof, will best be understood with reference to the following detailed description of exemplary embodiments of the present disclosure when read in conjunction with the accompanying drawings, wherein:

FIG. 1 shows a schematic diagram of a conventional switched beamforming circuit;

FIG. 2 is a block diagram illustrating an antenna system constructed according to an embodiment of the present disclosure;

FIG. 3 is a circuit diagram illustrating an antenna switching system constructed according to an embodiment of the present disclosure;

FIG. 4A shows a schematic diagram of the antenna array according to an embodiment of the present disclosure;

FIG. 4B shows a radiation pattern of the antenna array according to the embodiment of the present disclosure;

FIG. 5 is a circuit diagram illustrating an antenna switching system constructed according to another embodiment of the present disclosure;

FIG. 6A shows a schematic diagram of the antenna array according to another embodiment of the present disclosure;

FIG. 6B shows a radiation pattern of the antenna array according to another embodiment of the present disclosure;

FIG. 7 is a circuit diagram illustrating an antenna switching system constructed according to yet another embodiment of the present disclosure;

FIG. 8A is a circuit diagram illustrating an antenna switching system constructed according to the present disclosure;

FIG. 8B shows a schematic diagram of the antenna array according to another embodiment of the present disclosure;

FIG. 9 is a block diagram of an antenna switching system in accordance with another exemplary embodiment of the present disclosure; and

FIG. 10 is a block diagram of an antenna switching system in accordance with another exemplary embodiment of the present disclosure.

FIG. 11 is a circuit diagram of an antenna switching system in accordance with yet another exemplary embodiment of the present disclosure.

FIG. 12 shows a radiation pattern of the antenna array according to the embodiment of the present disclosure

The detailed description set forth below is intended as a description of exemplary designs of the present disclosure and is not intended to represent the only designs in which the present disclosure can be practiced. The term “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any design described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other designs. The detailed description includes specific details for the purpose of providing a thorough understanding of the exemplary designs of the present disclosure. It will be apparent to those skilled in the art that the exemplary designs described herein may be practiced without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the novelty of the exemplary designs presented herein.

FIG. 2 is a block diagram illustrating an antenna system constructed according to an embodiment of the present disclosure. Referring to FIG. 2 , the antenna system 1 is adapted to be applied in a wireless transmission device, such as a wireless router. The wireless communication system architecture of the antenna system 1 includes a system mainboard 10 and an antenna switching system 12 . The system mainboard 10 includes a power supply 100 , a processor 102 , a storage device 104 , and a general purpose input/output (GPIO) interface 106 . The antenna switching system 12 includes a first radio frequency (RF) circuit 120 , a second RF circuit 122 , a first polarization switching circuit 124 , a second polarization switching circuit 126 , and an antenna array 128 . In another embodiment, the first radio frequency (RF) circuit 120 , the second RF circuit 122 , the first polarization switching circuit 124 and the second polarization switching circuit 126 may be disposed on the system mainboard 10 .

The processor 102 is electrically connected to the power supply 100 , the storage device 104 , and the general purpose input/output (GPIO) interface 106 , respectively. The processor 102 may include any custom-made or commercially available processor, a central processing unit (CPU), or application specific integrated circuits (ASICs).

The storage device 104 can include any one of a combination of volatile memory elements (e.g., random-access memory (RAM, such as DRAM, and SRAM, etc.)) or nonvolatile memory elements.

The power supply 100 may include a power source, a regulator, and a power management module to provide the required power to the processor 102 and the antenna switching system 12 .

Each of the first RF circuit 120 and the second RF circuit 122 may be a transceiver or an RF IC, and it can generate a transmission signal to the first polarization switching circuit 124 or the second polarization switching circuit 126 or process a reception signal from the first polarization switching circuit 124 or the second polarization switching circuit 126 . The first RF circuit 120 and the second RF circuit 122 may each include a power amplifier.

The processor 102 may provide control signals to the first RF circuit 120 and the second RF circuit 122 for transmitting and receiving signals RF1 and RF2 through the first polarization switching circuit 124 and the second polarization switching circuit 126 , respectively, and the processor 102 may provide switching signals SWS to the first polarization switching circuit 124 and the second polarization switching circuit 126 through GPIO interface 106 . In order to form the desired single beam and combined beam, the processor 102 is configured to execute the antenna switching algorithm stored in the storage device 104 to control the first polarization switching circuit 124 and the second polarization switching circuit 126 to be switched to certain antenna(s) of the antenna array 128 . The antenna array 128 includes a plurality of antennas electrically connected to the first polarization switching circuit 124 and the second polarization switching circuit 126 via wires 1 st-pol#1 to 1 st-pol#N and wires 2nd-pol#1 to 2nd-pol#N assigned to multiple antenna sectors. Each antenna sectors can provide two types of polarization operation, for example, Horizontal polarization and Vertical polarization operations, so the entire antenna array 128 has a plurality of Horizontal polarization feeding points and a plurality of Vertical polarization feeding points. Furthermore, different types of linear polarization and circular polarization operations may also be provided.

Although the first RF circuit 120 , the second RF circuit 120 , the first polarization switching circuit 124 and the second polarization switching circuit 126 are provided in the present embodiment, the antenna switching system may include merely one RF circuit and one polarization switching circuit.

Reference is now made to FIG. 3 , which is a circuit diagram illustrating an antenna switching system constructed according to an embodiment of the present disclosure. The antenna switching system 12 includes the first RF circuit 120 , a first switch circuit 124 ′, and three first antennas A 1 - 1 , A 1 - 2 and A 1 - 3 . The first switch circuit 124 ′ includes a master switch MSW, three power divider PD 1 , PD 2 and PD 3 , and three switches SW 1 , SW 2 and SW 3 . The master switch MSW may be a single pole six throw (SP6T) switch, which includes a first common port CP 1 , three power divider (PD) ports PDP 1 , PDP 2 and PDP 3 , and three first ports P 1 , the first common port CP 1 is electrically connected to the first RF circuit 120 , and a number of the plurality of PD ports PDP 1 , PDP 2 and PDP 3 is equal to a number of the plurality of first ports P 1 .

Each of the power dividers PD 1 , PD 2 and PD 3 includes a second common port CP 2 , a second port P 2 , and a third port P 3 . The second common ports CP 2 are electrically connected to the PD ports PDP 1 , PDP 2 and PDP 3 of the master switch MSW, respectively.

In detail, the power dividers used herein are passive microwave components used for power division or power combining. In power division, an input signal is divided into two (or more) output signals of lesser power, while a power combiner accepts two or more input signals and combines them at an output port. The coupler or divider may have three ports, four ports, or more, and may be (ideally) lossless. Three-port networks take the form of T-junctions and other power dividers, while four-port networks take the form of directional couplers and hybrids. Power dividers usually provide in-phase output signals with an equal power division ratio (3 dB), but unequal power division ratios are also possible.

In this case, a Wilkinson power divider may be utilized, which is such a network with the useful property of appearing lossless when the output ports are matched; that is, only reflected power from the output ports is dissipated.

The three switches SW 1 , SW 2 and SW 3 , each may be a single pole triple throw (SP3T) switch and includes a third common port CP 3 , a fourth port P 4 , a fifth port P 5 , and a sixth port P 6 , and a number of the switches SW 1 , SW 2 and SW 3 is equal to the number of the first ports P 1 . The fourth ports P 4 of the switches SW 1 , SW 2 and SW 3 are electrically connected to the first ports P 1 , respectively, the fifth ports P 5 of the switches SW 1 , SW 2 and SW 3 are electrically connected to the second ports P 2 of the power dividers PD 1 , PD 2 and PD 3 , respectively, the sixth ports P 6 of the switches SW 1 , SW 2 and SW 3 are electrically connected to the third ports P 3 of the power dividers PD 1 , PD 2 and PD 3 , respectively, and the fifth port and the sixth port of each of the switches SW 1 , SW 2 and SW 3 are electrically connected to different ones of the power dividers PD 1 , PD 2 and PD 3 , respectively.

The master switch MSW is powered by a power line VCC and controlled by control line set CON 1 to select one signal path for the first common port CP 1 to transmit/receive RF signals through one of the first ports P 1 , or one of the PD ports PDP 1 , PDP 2 and PDP 3 . In other words, according to the control line set CON 1 given to the master switch MSW, the master switch MSW couples the first RF circuit 120 to either one of the three first ports P 1 , or one of the PD ports PDP 1 , PDP 2 and PDP 3 .

Each of the switches SW 1 , SW 2 and SW 3 is powered by a power line VCC and controlled by control lines IN 1 and IN 2 to select a signal path for the third common port CP 3 to transmit/receive RF signals through the fourth port P 4 , the fifth port P 5 , or the sixth port P 6 . In other words, according to the control lines IN 1 and IN 2 given to the switches SW 1 , SW 2 and SW 3 , the switches SW 1 , SW 2 and SW 3 are configured to couple the first antennas A 1 - 1 , A 1 - 2 and A 1 - 3 to either the first ports P 1 , or the power divider PD 1 , PD 2 and PD 3 . Since each of the switches SW 1 , SW 2 and SW 3 may be SP3T, and control lines IN 1 and IN 2 are 2 bits, four combinations may be provided for satisfying the switching combinations of the SP3T.

The three first antennas A 1 - 1 , A 1 - 2 and A 1 - 3 coupled to the third common ports CP 3 of the three second switches SW 1 , SW 2 and SW 3 , respectively.

The present embodiment is an example of the antenna switching system with two antenna sectors. All of the switches can be switched and controlled by the processor 102 through the GPIO interface GPIO. First, when single-beam operation of the first antenna A 1 - 1 is to be achieved, the first common port CP 1 of the master switch MSW is switched to the first port P 1 coupled to the switch SW 1 , and the third common port CP 3 of the switch SW 1 is also switched to the fourth port P 4 . Similarly, when single-beam operation of the first antenna A 1 - 2 or A 1 - 2 is to be achieved, the master switch MSW and the switch SW 2 or SW 3 perform switching operation as similar as the switching operation described above.

Secondly, when a combined-beam operation of the first antennas A 1 - 1 and A 1 - 2 is to be achieved, the first common port CP 1 of the master switch MSW is switched to the PD port PDP 1 , and the third common port CP 3 of the switch SW 1 is switched to the sixth port P 6 , and the third common port CP 3 of the switch SW 2 is switched to the fifth port P 5 . When RF signals pass through the 3 dB power divider PD, the power divider PD divides or combines the RF signals of adjacent antenna sectors to transmit or receive signals.

An important consideration in achieving a combined-beam is the phase balance of the two synthesis paths. Otherwise, the RF signals are easily subtracted from each other at the time of synthesis. Therefore, the SP3 Ts of the three switches SW 1 , SW 2 and SW 3 may be identical, for example, using the same model of components. The antenna switching system provided in the present disclosure has a symmetrical architecture, such that the required phase balance may be easily achieved. Furthermore, the low return loss, low insertion loss and equal insertion loss and phases between the two synthesis paths may also be achieved by utilizing the symmetrical architecture.

Reference is now made to FIGS. 4A and 4B . FIG. 4A shows a schematic diagram of the antenna array according to an embodiment of the present disclosure, FIG. 4B shows a radiation pattern of the antenna array according to the embodiment of the present disclosure.

The antenna array of FIG. 4A includes three antenna sectors. Each antenna sector covers a sector area of about 120 degrees. Each of the antenna sectors includes four antennas. Each antenna sectors has, for examples, the first antennas A 1 - 1 , A 1 - 2 and A 1 - 3 (not shown). Each antenna sector forms a single beam that can transmit and receive RF signals individually, and can also be combined with adjacent antenna sectors to form a combined beam to transmit and receive RF signals. As shown in FIG. 4B , a first radiation pattern 41 formed by the first antenna A 1 - 1 is toward to a first direction D 1 , a second radiation pattern 42 formed by the first antenna A 1 - 2 is toward to a second direction D 2 , a third radiation pattern 43 formed by the first antenna A 1 - 3 is toward to a third direction D 3 , and when the first common port CP 1 is switched to the PD port PDP 1 , a radiation pattern formed by the first antenna A 1 - 1 and A 1 - 2 is toward to a fourth direction D 4 . Therefore, a angle resolution of radiation patterns can be increased by two single beams and one combined beam. Radiation patterns 44 , 45 , and 46 may further be formed by the first antenna A 1 - 1 and A 1 - 2 , A 1 - 2 and A 1 - 3 , and A 1 - 3 and A 1 - 1 , respectively. The total number of radiation patterns for all single beams and combined beams are 6, and the radiation patterns 41 , 42 , 43 , 44 , 45 , and 46 with different angles provide a communication area without any dead corner.

Reference is now made to FIG. 5 , which is a circuit layout illustrating an antenna switching system constructed according to another embodiment of the present disclosure. As shown in FIG. 5 , the antenna switching system 12 ′ includes the first RF circuit 120 , a first switch circuit 124 ″, and six first antennas A 1 - 1 through A 1 - 6 . In the present embodiment, the first RF circuit 120 , the power dividers PD 1 thorough PD 6 , and the switches SW 1 through SW 6 are as the same as those depicted in the FIG. 3 , therefore, the repeated descriptions are omitted.

Differently, the master switch MSW may include six first ports P 1 and six PD ports PDP 1 through PDP 6 , and may be a single pole twelve throw (SP12T) switch. The first switch circuit 124 ″ in the present embodiment further includes two three switches SW 4 , SW 5 and SW 6 and three power dividers PD 4 , PD 5 and PD 6 . Each of the three switches SW 4 , SW 5 and SW 6 may be a SP3T switch and may each includes a third common port CP 3 , fourth, fifth and sixth ports as mentioned in the previous embodiment. Reference numerals of the ports of the power dividers PD 1 thorough PD 6 and the switches SW 1 through SW 6 will be omitted hereinafter to avoid repeated descriptions.

The six first antennas A 1 - 1 through A 1 - 6 are respectively coupled to the third common ports of the switches SW 1 through SW 6 . The third common port of each of the switches SW 1 through SW 6 is selectively switched to one of the fourth, fifth, and sixth ports. In more detail, each of the switches SW 1 through SW 6 is powered by a power line and controlled by control lines to select one signal path for the third common port to transmit/receive RF signals through one of the fourth, fifth, and sixth ports. In other words, according to the signals given to the switches SW 1 through SW 6 via the control lines, the switches SW 1 through SW 6 couples the third common port to either one of the fourth, fifth, and sixth ports.

The present embodiment is an example of the antenna switching system with six antenna sectors. All of the switches can be switched and controlled by the processor 102 through the GPIO interface GPIO. First, when single-beam operation of one of the first antenna A 1 - 1 through A 1 - 6 is to be achieved, the first common port CP 1 of the master switch MSW is switched to one of the first ports P 1 , the third common port CP 3 of the switches SW 1 through SW 6 coupled to the selected one of the first antennas A 1 - 1 through A 1 - 6 is also switched to the fourth port.

Secondly, when a combined-beam operation of one of the combinations between the first antennas A 1 - 1 and A 1 - 2 , between the first antennas A 1 - 2 and A 1 - 3 , between the first antennas A 1 - 3 and A 1 - 4 , between the first antennas A 1 - 4 and A 1 - 5 , between the first antennas A 1 - 5 and A 1 - 6 , and between the first antennas A 1 - 6 and A 1 - 1 is to be achieved, the first common port CP 1 of the master switch MSW is switched to one of the PD ports PDP 1 through PDP 6 corresponding to the selected combination of two first antennas among the first antennas A 1 - 1 through A 1 - 6 , the two switches among the six switches SW 1 through SW 6 coupled to the selected combination of two first antennas among the first antennas A 1 - 1 through A 1 - 6 are switched to couple the two first antennas to the selected power divider. When RF signals pass through the 3 dB power divider PD, the power divider PD divides or combines the RF signals of adjacent antenna sectors to transmit or receive signals.

Although the six first ports P 1 , the six power dividers PD 1 through PD 6 , the six switches SW 1 through SW 6 , and the six first antennas A 1 - 1 through A 1 - 6 are provided, the numbers of these components are not limited to the present embodiment. The numbers of these components may each be an integer equals to or larger than three.

Similarly, the phase balance of the two adjacent synthesis paths are considered for achieving a combined-beam. The SP3 Ts of the six second switches SW 1 through SW 6 may be identical, and the power dividers PD 1 through PD 6 may be identical. The antenna switching system provided in the present disclosure has a symmetrical architecture, such that the required phase balance may be easily achieved. Furthermore, the low return loss, low insertion loss and equal insertion loss and phases between the two synthesis paths may also be achieved by utilizing the symmetrical architecture.

Reference is now made to FIGS. 6A and 6B . FIG. 6A shows a schematic diagram of the antenna array according to another embodiment of the present disclosure, and FIG. 6B shows a radiation pattern of the antenna array according to another embodiment of the present disclosure.

The antenna array of FIG. 6A includes six antenna sectors. Each antenna sector covers a sector area of about 60 degrees. Each of the antenna sectors may include four antenna elements (e.g., patch antenna) that form a single antenna. Each antenna sectors has, for examples, the first antennas A 1 - 1 through A 1 - 6 . Each antenna sector forms a single beam that can transmit and receive RF signals individually, and can also be combined with adjacent antenna sectors to form a combined beam to transmit and receive RF signals. In the embodiment, the first antennas A 1 - 1 through A 1 - 6 are spaced at equal intervals around a circumference of a circle, but the arrangement is not limited to this embodiment, the first antennas A 1 - 1 through A 1 - 6 are spaced at equal intervals along a straight line, or the arrangement may be provided by spacing at unequal intervals to form other shapes.

As shown in FIG. 6B , a first radiation pattern 601 formed by the first antenna A 1 - 1 is toward to a first direction D 1 , a second radiation pattern 602 formed by the first antenna A 1 - 2 is toward to a second direction D 2 , a third radiation pattern 603 formed by the first antenna A 1 - 3 is toward to a third direction D 3 , a fourth radiation pattern 604 formed by the first antenna A 1 - 4 is toward to a fourth direction D 4 , a fifth radiation pattern 605 formed by the first antenna A 1 - 5 is toward to a fifth direction D 5 , and a sixth radiation pattern 606 formed by the first antenna A 1 - 6 is toward to a sixth direction D 6 . When the first common port CP 1 is switched to the PD port PDP, a seventh radiation pattern 607 formed by the first antennas A 1 - 1 and A 1 - 2 may be toward to a seventh direction D 7 , an eighth radiation pattern 608 formed by the first antennas A 1 - 2 and A 1 - 3 may be toward to an eighth direction D 8 , a ninth radiation pattern 609 formed by the first antennas A 1 - 3 and A 1 - 4 may be toward to a ninth direction D 9 , a tenth radiation pattern 610 formed by the first antennas A 1 - 4 and A 1 - 5 may be toward to a tenth direction D 10 , an eleventh radiation pattern 611 formed by the first antennas A 1 - 5 and A 1 - 6 may be toward to a eleventh direction D 11 , a twelfth radiation pattern 612 formed by the first antennas A 1 - 6 and A 1 - 1 may be toward to a twelfth direction D 12 . Therefore, a higher angle resolution of radiation patterns can be provided without any dead corner by utilizing the six single beams and six combined beams.

Moreover, when considering that two adjacent first antennas among n first antennas would participate in the combined beam operation, the antenna switching system 12 ′ may be designed according to the following statement: an i th first antenna is electrically connected to an i th switch, where i is an integer from 1 to n−1, and an i th power divider of plurality of power dividers is electrically connected to the i th switch and an (i+1) th switch of the plurality of switches, and a n th power divider is electrically connected to a n th switch and a 1 st switch of the plurality of switches, and n is equal to the number of the plurality of switches. For example, suppose two first antennas are participating in the combined beam operation, and six first antennas are included in the antenna array and arranged in sequence, i.e., in an order of 1st to 6 th . Therefore, a master switch should be a SP12T switch, and six switches and six power dividers should be provided. Furthermore, the 1 st first antenna is electrically connected to an 1 st switch, a 1 st power divider is electrically connected to the 1 st switch and an 2nd switch of the six switches, and a 6th power divider is electrically connected to a 6th switch and a 1 st switch of the six switches.

Specifically, the SP3T/SP6T/SP12T RF switches and 3 dB power divider/combinator used in the present disclosure are commercially available in any frequency band, and generally, the 50-ohm impedance matching of each switch has basically been completed before shipment. No impedance mismatch problem existed for either the single beam or the combined beam operation. The isolation of the single beam for each antenna sector is achieved by the circuit isolation between the adjacent two of the six switches SW 1 through SW 6 at the last stage. The isolation of the combined beams of two adjacent antenna sectors is achieved by the circuit isolation between the second port and the third port of the 3 dB power split/combinator, and isolations more than 20 dB may be basically achieved by utilizing the SP3T/SP6T/SP12T RF switches and 3 dB power divider/combinator in this architecture.

A single beam or combined beam operation for any number of antenna sectors may also be achieved by simply replacing the power dividers and the switches in the present embodiment, which will be described in more detail hereinafter.

Reference is now made to FIG. 7 , which is a circuit diagram illustrating an antenna switching system constructed according to yet another embodiment of the present disclosure. As shown in FIG. 7 , the antenna switching system 12 ″ includes the first RF circuit 120 , a first switch circuit 124 ″, and first antennas A 1 - 1 through A 1 - 2 N. In the present embodiment, the first RF circuit 120 , configurations of the fourth, fifth, sixth ports of each of the switches SW 1 through SWN, and configurations of the second and third ports of the power dividers PD 1 through PDN are as the same as those depicted in the FIG. 3 , therefore, the repeated descriptions are omitted.

In this case, a number of the first ports of the master switch MSW, a number of the PD ports PDP 1 through PDPN, a number of the power dividers PD 1 through PDN, and numbers of the switches SW 1 through SWN may be equal to one another. Each of the power dividers PD 1 through PDN may further include a seventh port, and each of the switches SW 1 through SWN may further include a eighth port, such that there are three first antennas may participating in the combined beam operation. Specifically, the seventh ports of the power dividers PD 1 through PDN are electrically connected to the eighth ports of the switches SW 1 through SWN, respectively, and the fifth port, the sixth port, and the eighth port of each of the switches SW 1 through SWN are electrically connected to different ones of the power dividers PD 1 through PDN, respectively, and each of the power dividers PD 1 through PDN may be a 3-way power divider.

In the present embodiments, multiple ports may be further included in each of the power dividers PD 1 through PDN and each of the switches SW 1 through SWN according to a required number of first antennas participating in the combined beam operation. For example, if four first antennas are expected to participate in the combined beam operation, the power dividers PD 1 through PDN may each be a 4-way power divider, and the switches SW 1 through SWN may each be a SW4T switch, such that each of the combined beams may be formed by four antenna sectors.

Based on the architecture of the present embodiment, the master switch MSW may further be a SP2NT switch, and each of the switches SW 1 through SWN may further be a SP4T switch. The first antennas A 1 - 1 through A 1 -N are respectively coupled to the third common ports of the switches SW 1 through SWN. Furthermore, the first antennas A 1 - 1 through A 1 -N may be arranged in sequence and spaced at equal intervals around a circumference of a circle, but the arrangement is not limited to this embodiment, the first antennas A 1 - 1 through A 1 -N may be spaced at equal intervals along a straight line, or the arrangement may be provided by spacing at unequal intervals to form other shapes.

The third common port of each of the switches SW 1 through SWN is selectively switched to one of the fourth, fifth, sixth and eighth ports. In more detail, each of the switches SW 1 through SWN is powered by a power line and controlled by control lines to select a signal path for the third common port to transmit/receive RF signals through one of the fourth, fifth, sixth and eighth ports. In other words, according to the control lines given to the switches SW 1 through SWN, each of the switches SW 1 through SWN is configured to couple the third common port P 3 to one of the fourth, fifth, sixth and eighth ports.

The present embodiment is an example of the antenna switching system with N antenna sectors. All of the switches can be switched and controlled by the processor 102 through the GPIO interface GPIO. First, when single-beam operation of one of the first antenna A 1 - 1 through A 1 -N is to be achieved, the first common port CP 1 of the master switch MSW is switched to one of the first ports P 1 , and the third common port CP 3 of the switches SW 1 through SWN coupled to the selected one of the first antennas A 1 - 1 through A 1 -N is also switched to the fourth port.

Secondly, when a combined-beam operation of one of the combinations between the two adjacent first antennas among the first antennas A 1 - 1 through A 1 -N is to be achieved, the first common port CP 1 of the master switch MSW is switched to one of the PD ports PDP 1 through PDPN corresponding to the selected combination of two adjacent first antennas among the first antennas A 1 - 1 through A 1 -N, the two switches among the N switches SW 1 through SWN coupled to the selected combination of two adjacent first antennas among the first antennas A 1 - 1 through A 1 -N are switched to couple the two first antennas to the selected power divider. When RF signals pass through the 3 dB power divider PD, the power divider PD divides or combines the RF signals of adjacent antenna sectors to transmit or receive signals. When RF signals pass through the 3 dB power divider PD, the power divider PD divides or combines the RF signals of adjacent antenna sectors to transmit or receive signals. It is notably mentioned that the numbers of the first ports P 1 , the PD ports PDP 1 through PDPN, and the first antennas may be at least three.

From above, the single beam or combined beam operation for any number of antenna sectors may also be achieved by simply adjusting numbers of the ports of the master switch, the numbers and types of the power divider and the switches at last stage in the present disclosure.

Reference is now made to FIGS. 7, 8A and 8B . FIG. 8A is a circuit diagram illustrating an antenna switching system constructed according to the present disclosure, and FIG. 8B shows a schematic diagram of the antenna array according to another embodiment of the present disclosure.

As shown in FIGS. 7, 8A and 8B , the antenna switching system 12 further includes the second RF circuit 122 , the second polarization switching circuit 126 , and a plurality of second antennas A 2 - 1 through A 2 -N included in the antenna array 128 . The second polarization switching circuit 126 is configured to be as the same as the first polarization switching circuit 124 ″ as depicted in FIG. 7 . In this case, the first common port CP 1 of the second polarization switching circuit 126 is coupled to the second RF circuit 122 , and the second antennas A 2 - 1 through A 2 -N are coupled to the third common ports of the second polarization switching circuit 126 . Similarly, a number of the second antenna A 2 - 1 through A 2 -N may be at least three. In consideration for providing two types of polarization operation, for example, Horizontal polarization and Vertical polarization operations, the entire antenna array 128 , as shown in FIG. 8B , may have a plurality of Horizontal polarization feeding points and a plurality of Vertical polarization feeding points. Furthermore, different types of linear polarization and circular polarization operations may also be provided. Furthermore, types of polarization may be determined according to the positions and orientations of the antennas. For example, each of the antenna sectors may include four patch antennas, two for serving the first antennas A 1 - 1 , A 1 - 2 or A 1 - 3 , and the other two for serving the second antennas A 2 - 1 , A 2 - 2 , or A 2 - 3 , such that the radiation patterns of the two types of polarization may be provided from each antenna sector. For example, the first antennas A 1 - 1 , A 1 - 2 and A 1 - 3 may be constructed as horizontal polarization antennas, and the second antennas A 2 - 1 , A 2 - 2 , and A 2 - 3 may be constructed as vertical polarization antennas.

FIG. 9 is a block diagram of an antenna switching system in accordance with another exemplary embodiment of the present disclosure. The antenna switching system 2 includes a RF circuit 20 for transceiving signals, N antennas B 1 through BN, a master switch 22 , N switches SW 1 through SWN, power dividers PD 1 through PDN. The master switch 22 is electrically connected to the RF circuit 20 , a i th switch of the N switches SW 1 through SWN is electrically connected between the master switch 22 and a i th antenna of the N antennas B 1 through BN, where i is an integer from 1 to N, and N is an integer equal to or larger than 3, and a j th power divider of N power dividers PD 1 through PDN is electrically connected between the master switch 22 and a j th switch of the N switches SW 1 through SWN, and between the master switch 22 and a (j+1) th switch of the N switches SW 1 through SWN, where j is an integer from 1 to N−1.

The N th power divider PDN of the N power dividers PD 1 through PDN is electrically connected between the master switch 22 and a N th switch SWN, and between the master switch 22 and a 1 st switch SW 1 of the N switches SW 1 through SWN. The signals may be transmitted by one of the N antennas B 1 through BN, or the signals may be transmitted by the two antennas of the N antennas B 1 through BN corresponding to the two switches among the switches SW 1 through SWN connected to one of the N power dividers PD 1 through PDN. Specifically, the adjacent two antennas of the N antennas B 1 through BN are preferably selected to transmit the signals for achieving better performance and better uniformity of the radiation patterns.

In the present embodiment, the master switch 22 may be a SP2NT switch, the power dividers PD 1 through PDN may each be a Wilkinson power divider, and the switches SW 1 through SWN may each be a SPDT switch. Therefore, signals may be transmitted by one of the first antenna B 1 through BN in the single beam operation, or may be transmitted by one of combinations between two adjacent first antennas among the first antenna B 1 through BN. The antenna switching system provided in the present embodiment has a symmetrical architecture, such that the required phase balance may be easily achieved. Similarly, the N first antennas B 1 through BN may be arranged in sequence, i.e., in an order of B 1 , B 2 , . . . BN, and the N first antennas B 1 through BN may be arranged in a circle.

FIG. 10 is a block diagram of an antenna switching system in accordance with another exemplary embodiment of the present disclosure. As shown in FIG. 10 , the antenna switching system 2 ′ is almost the same as those depicted in the FIG. 9 , except that three antennas of N antennas B 1 through BN would participate in each of the combined beam operations.

In this architecture, the j th power divider of N power dividers PD 1 through PDN is further electrically connected between the master switch 22 and a (j+2) th switch of the N switches SW 1 through SWN, and a (N−1) th power divider PD(N−1) of the N power dividers PD 1 through PDN is further electrically connected between the master switch 22 and a 1st switch SW 1 , and the N th power divider PDN of the N power dividers PD 1 through PDN is further connected between the master switch 22 and a 2 nd switch SW 2 of the N switches. Furthermore, the power dividers PD 1 through PDN may each be a 3-way power divider, and the switches SW 1 through SWN may each be a SP3T switch.

In the single beam operation, the signals may transmitted by one of the N antennas B 1 through BN, or the signals may be transmitted by three antennas of the N antennas B 1 through BN corresponding to the switches connected to one of the N power dividers PD 1 through PDN in the combined beam operation. Specifically, the adjacent three antennas of the N antennas B 1 through BN are preferably selected to transmit the signals for achieving better performance and better uniformity of the radiation patterns.

In some embodiments, the antennas B 1 through BN may be arranged in a circle. In the embodiment, the antennas B 1 through BN may be spaced at equal intervals around a circumference of a circle, but the arrangement is not limited to this embodiment, the antennas B 1 through BN may be spaced at equal intervals along a straight line, or the arrangement may be provided by spacing at unequal intervals to form other shapes, thereby to form radiation patterns according to the requirement of the designer.

Furthermore, the number of the antennas participated in the combined beam operations may be more than 2. In this case, the numbers of the ports of the power dividers and the switches at last stage may be simply adjusted in order to fulfill the requirement of single beam and combined beam operations. The detailed configuration may be designed according to the embodiments depicted in FIGS. 3, 5, 7 and 8A .

FIG. 11 is a block diagram of an antenna switching system in accordance with yet another exemplary embodiment of the present disclosure. An antenna switching system 3 includes a RF circuit 30 , a switch circuit 32 , a first antenna C 1 , a second antenna C 2 , and a third antenna C 3 .

The switch circuit 32 includes a master switch 320 , a first switch 322 , a second switch 324 , a third switch 326 , a first power divider (PD) PD 1 and a second power divider (PD) PD 2 . The master switch 320 includes a first common port CP 1 , a first power divider (PD) port PDP 1 and a second PD port PDP 2 , a first port P 1 , a second port P 2 , and a third port P 3 , and the first common port CP 1 is electrically connected to the first RF circuit 30 .

The first switch 322 is electrically connected to the first antenna C 1 and the master switch 320 , the second switch 324 is electrically connected to the second antenna C 2 and the master switch 320 , and the third switch 326 is electrically connected to a third antenna C 3 and the master switch 320 .

The first power divider (PD) PD 1 and a second power divider (PD) PD 2 each includes a second common port CP 2 , a fourth port P 4 and a fifth port P 5 . The second common ports CP 2 of the first PD PD 1 and the second PD PD 2 are electrically connected to the first PD port PDP 1 and the second PD port PDP 2 , respectively, the fourth ports P 4 of the first PD PD 1 and the second PD PD 2 are electrically connected to the first switch 322 and the second switch 324 , respectively, and the fifth ports P 5 of the first PD PD 1 and the second PD PD 2 are electrically connected to the second switch 324 and the third switch 326 , respectively.

Reference is now made to FIG. 12 , FIG. 12 shows a radiation pattern of the antenna array according to the embodiment of the present disclosure. As shown in the FIG. 12 , a first radiation pattern RP 1 is formed by the first antenna C 1 , a second radiation pattern RP 2 is formed by the second antenna C 2 , and a third radiation pattern RP 3 is formed by the third antenna C 3 . When the first common port CP 1 is switched to the first PD port PDP 1 , a radiation pattern RP 12 formed by the first antenna C 1 and the second antenna C 2 is toward to a first direction D 1 ′, and when the first common port CP 1 is switched to the second PD port PDP 2 , a radiation pattern RP 23 formed by the second antenna C 2 and the third antenna C 3 is toward to a second direction D 2 ′. Therefore, an angle resolution of radiation patterns can be increased by three single beams and two combined beam.

In certain embodiment, the first switch 322 and the third switch 326 each may be the SPDT as mentioned above, the second switch 324 may be SP3T switch as mentioned above, the first PD PD 1 and the second PD PD 2 may be Wilkinson power dividers, and the first switch 322 , the second switch 324 , and the third switch 326 may be controlled by the processor to perform the single beam operation and the combined beam operation.

From above, the antenna switching system of the present disclosure provides a circuit architecture for the smart antenna that may achieve a high angle resolution of radiation patterns by utilizing plural switches, while achieving the required phase balance in the combined-beam operation with the symmetrical architecture. Furthermore, the low return loss, low insertion loss and equal insertion loss and phases between the two synthesis paths may also be achieved by utilizing the symmetrical architecture.

The antenna switching system of the present disclosure is also provided without utilizing any diode. The control circuit for the antenna switching system may operate at low operation voltage and without supplying voltages greater than 5V. Therefore, the system mainboard does not require any DC to DC converters, and the costs may be reduced accordingly.

Moreover, no impedance mismatch existed for either the single beam or the combined beam operation in the antenna switching system of the present disclosure. The isolation of the single beam for each antenna sector may be achieved by the circuit isolation between the switches at the last stage.

Furthermore, design rules are also provided in the present disclosure, such that the single beam or combined beam operation for any number of antenna sectors may also be achieved by simply adjusting the numbers of the ports of the power dividers and the switches at the last stage.

The description of the different exemplary embodiments has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different exemplary embodiments may provide different advantages as compared to other exemplary embodiments. The embodiment or embodiments selected are chosen and described in order to best explain the principles of the disclosure, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.