Power divider and radio-frequency transceiver system

A radio-frequency transceiver system comprises a radio-frequency processing unit, a transmitting microwave network and a receiving microwave network, wherein the transmitting microwave network comprises a transmitting power divider for distributing main power of transmitting signals to two central sub-array antennas of four sub-array antennas, and the receiving microwave network comprises a receiving power divider for providing power mainly from a first input terminal and a second input terminal for a receiving route, and providing power mainly from the second input terminal and a third input terminal for another receiving route.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power divider and a radio-frequency transceiver system, and more particularly, to a power divider and a radio-frequency transceiver system capable of effectively enhancing an array antenna gain, reducing an array antenna area, optimizing an antenna radiation pattern, reducing a reflection loss, and enhancing a side lobe suppression capability.

2. Description of the Prior Art

An array antenna is an antenna system consisting of a plurality of identical antennas arranged according to a certain rule, and is widely used in a radar system. The commonly-seen array antenna system is implemented by a manufacturing process of a printed circuit board, and antennas and a power divider are disposed in different layers of a substrate. In order to connect signals between different layers, a via hole is taken as a bridge. However, since transmission of the signals between the different layers only relies on the via hole, when a position of the via hole is changed due to a process variation or a process inaccuracy, frequency shift occurs and an overall system performance is reduced. Moreover, since an operating frequency of the radar system is mostly utilized in a microwave frequency band, as the operating frequency is getting higher, a distance passed through the via hole may be longer. When the distance is close to a quarter wavelength of the signals, an impedance matching issue would become more serious. As a result, the corresponding design becomes more complex and the antenna gain is reduced, leading to a shorter detecting distance and a narrower scanning angle.

Therefore, how to avoid the frequency shift and the degradation of antenna performance of the array antenna due to the process inaccuracy of wiring between different layers has become an industry target. Moreover, to further enhance the antenna gain, so as to enhance the detecting distance or reduce a required area, is also the industry target.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide a power divider and a radio-frequency transceiver system.

The present invention discloses a power divider, for transmitting a signal of an input terminal to a first output terminal, a second output terminal, a third output terminal, and a fourth output terminal. The power divider comprises a first connecting wire, comprising a first terminal and a second terminal; a second connecting wire, comprising a first terminal and a second terminal; a first ring-shaped transmission unit, comprising a first ground element and a first ring-shaped conductive circle surrounding the first ground element, wherein a first terminal of the first ring-shaped conductive circle is electrically connected to the input terminal, a second terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the first connecting wire, and a third terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the second connecting wire, wherein a width of the first ring-shaped conductive circle is substantially equal to a first value; a second ring-shaped transmission unit, comprising a second ground element and a second ring-shaped conductive circle surrounding the second ground element, wherein a first terminal of the second ring-shaped conductive circle is electrically connected to the second terminal of the first connecting wire, a second terminal of the second ring-shaped conductive circle is electrically connected to the first output terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the second output terminal, wherein the second ring-shaped conductive circle comprises a plurality of segments each with a length substantially equal to a quarter wavelength of the signal, and the plurality of segments are substantially divided into a plurality of groups according to widths of the segments; and a third ring-shaped transmission unit, comprising a third ground element and a third ring-shaped conductive circle surrounding the third ground element, wherein a first terminal of the third ring-shaped conductive circle is electrically connected to the second terminal of the second connecting wire, a second terminal of the third ring-shaped conductive circle is electrically connected to the fourth output terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the third output terminal, wherein the third ring-shaped conductive circle comprises a plurality of segments each with a length substantially equal to a quarter wavelength of the signal, and the plurality of segments are substantially divided into a plurality of groups according to widths of the segments.

The present invention further discloses a power divider, for transmitting signals of a first input terminal, a second input terminal, and a third input terminal to a first output terminal and a second output terminal. The power divider comprises a first connecting wire, comprising a first terminal and a second terminal; a second connecting wire, comprising a first terminal and a second terminal; a first ring-shaped transmission unit, comprising a first ground element and a first ring-shaped conductive circle surrounding the first ground element, wherein a first terminal of the first ring-shaped conductive circle is electrically connected to the second input terminal, a second terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the first connecting wire, and a third terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the second connecting wire, wherein a width of the first ring-shaped conductive circle is substantially equal to a first value; a second ring-shaped transmission unit, comprising a second ground element and a second ring-shaped conductive circle surrounding the second ground element, wherein a first terminal of the second ring-shaped conductive circle is electrically connected to the first output terminal, a second terminal of the second ring-shaped conductive circle is electrically connected to the first input terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the second terminal of the first connecting wire, wherein a width of the second ring-shaped conductive circle from the first terminal to the second terminal is substantially equal to a second value, and a width of the second ring-shaped conductive circle from the first terminal to the third terminal is substantially equal to a third value; and a third ring-shaped transmission unit, comprising a third ground element and a third ring-shaped conductive circle surrounding the third ground element, wherein a first terminal of the third ring-shaped conductive circle is electrically connected to the second output terminal, a second terminal of the third ring-shaped conductive circle is electrically connected to the third input terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the second terminal of the second connecting wire, wherein a width of the third ring-shaped conductive circle from the first terminal to the second terminal is substantially equal to a fourth value, and a width of the third ring-shaped conductive circle from the first terminal to the third terminal is substantially equal to a fifth value; wherein the second value is not equal to the third value, and the fourth value is not equal to the fifth value.

The present invention further discloses a radio-frequency transceiver system comprising a transmitting power divider, for transmitting a signal of an input terminal to a first output terminal, a second output terminal, a third output terminal, and a fourth output terminal, the transmitting power divider comprising a first connecting wire, comprising a first terminal and a second terminal; a second connecting wire, comprising a first terminal and a second terminal; a first ring-shaped transmission unit, comprising a first ground element and a first ring-shaped conductive circle surrounding the first ground element, wherein a first terminal of the first ring-shaped conductive circle is electrically connected to the input terminal, a second terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the first connecting wire, and a third terminal of the first ring-shaped conductive circle is electrically connected to the first terminal of the second connecting wire, wherein a width of the first ring-shaped conductive circle is substantially equal to a first value; a second ring-shaped transmission unit, comprising a second ground element and a second ring-shaped conductive circle surrounding the second ground element, wherein a first terminal of the second ring-shaped conductive circle is electrically connected to the second terminal of the first connecting wire, a second terminal of the second ring-shaped conductive circle is electrically connected to the first output terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the second output terminal, wherein the second ring-shaped conductive circle comprises a plurality of segments each with a length substantially equal to a quarter wavelength of the signal, and the plurality of segments are substantially divided into a plurality of groups according to widths of the segments; and a third ring-shaped transmission unit, comprising a third ground element and a third ring-shaped conductive circle surrounding the third ground element, wherein a first terminal of the third ring-shaped conductive circle is electrically connected to the second terminal of the second connecting wire, a second terminal of the third ring-shaped conductive circle is electrically connected to the fourth output terminal, and a third terminal of the second ring-shaped conductive circle is electrically connected to the third output terminal, wherein the third ring-shaped conductive circle comprises a plurality of segments each with a length substantially equal to a quarter wavelength of the signal, and the plurality of segments are substantially divided into a plurality of groups according to widths of the segments; a receiving power divider, for transmitting signals of a first input terminal, a second input terminal, and a third input terminal to a fifth output terminal and a sixth output terminal, the receiving power divider comprising a third connecting wire, comprising a first terminal and a second terminal; a fourth connecting wire, comprising a first terminal and a second terminal; a fourth ring-shaped transmission unit, comprising a fourth ground element and a fourth ring-shaped conductive circle surrounding the fourth ground element, wherein a first terminal of the fourth ring-shaped conductive circle is electrically connected to the second input terminal, a second terminal of the fourth ring-shaped conductive circle is electrically connected to the first terminal of the third connecting wire, and a third terminal of the fourth ring-shaped conductive circle is electrically connected to the first terminal of the fourth connecting wire, wherein a width of the fourth ring-shaped conductive circle is substantially equal to a first value; a fifth ring-shaped transmission unit, comprising a fifth ground element and a fifth ring-shaped conductive circle surrounding the fifth ground element, wherein a first terminal of the fifth ring-shaped conductive circle is electrically connected to the first output terminal, a second terminal of the fifth ring-shaped conductive circle is electrically connected to the first input terminal, and a third terminal of the fifth ring-shaped conductive circle is electrically connected to the second terminal of the third connecting wire, wherein a width of the fifth ring-shaped conductive circle from the first terminal to the second terminal is substantially equal to a second value, and a width of the fifth ring-shaped conductive circle from the first terminal to the third terminal is substantially equal to a third value; and a sixth ring-shaped transmission unit, comprising a sixth ground element and a sixth ring-shaped conductive circle surrounding the sixth ground element, wherein a first terminal of the sixth ring-shaped conductive circle is electrically connected to the second output terminal, a second terminal of the sixth ring-shaped conductive circle is electrically connected to the third input terminal, and a third terminal of the sixth ring-shaped conductive circle is electrically connected to the second terminal of the fourth connecting wire, wherein a width of the sixth ring-shaped conductive circle from the first terminal to the second terminal is substantially equal to a fourth value, and a width of the sixth ring-shaped conductive circle from the first terminal to the third terminal is substantially equal to a fifth value; wherein the second value is not equal to the third value, and the fourth value is not equal to the fifth value; a radio-frequency processing unit, for generating a differential transmitting signal, and processing a first differential receiving signal and a second differential receiving signal; a transmitting array antenna, comprising a first sub-array antennas, a second sub-array antennas, a third sub-array antennas, and a fourth sub-array antennas, respectively coupled to the first output terminal, the second output terminal, the third output terminal, and the fourth output terminal of the transmitting power divider; a receiving array antenna, comprising a fifth sub-array antennas, a sixth sub-array antennas, and a seventh sub-array antennas, respectively coupled to the first input terminal, the second input terminal, and the third input terminal of the receiving power divider; a first ring-shaped coupler, coupled between the radio-frequency processing unit and the input terminal of the transmitting power divider, for converting the differential transmitting signal to output to the input terminal; a second ring-shaped coupler, coupled between the radio-frequency processing unit and the fifth output terminal of the receiving power divider, for converting a signal of the fifth output terminal to the first differential receiving signal; and a third ring-shaped coupler, coupled between the radio-frequency processing unit and the sixth output terminal of the receiving power divider, for converting a signal of the sixth output terminal to the second differential receiving signal.

DETAILED DESCRIPTION

Please refer toFIG. 1, which illustrates a schematic diagram of a radio-frequency transceiver system10according to an embodiment of the present invention. The radio-frequency transceiver system10may be a microwave transceiver network of a radar system, such as an array antenna for car uses, etc., and is not limited herein. The radio-frequency transceiver system10is substantially disposed on the same plane, such as a bottom layer or an upper layer of a circuit board, and includes a transmitting power divider12, a receiving power divider14, a radio-frequency processing unit16, a transmitting array antenna18, a receiving array antenna20, and ring-shaped couplers22,24,26.

For a transmitting operation, differential signals to be transmitted are converted to single-ended signals by the ring-shaped coupler22, and are transmitted to an input terminal IPTx of the transmitting power divider12by the radio-frequency processing unit16. The transmitting power divider12may distribute the received signals to output terminals OP1, OP2, OP3, OP4with a relationship of a first power ratio, simultaneously performs a phase adjustment, and finally transmits the received signals to air via the transmitting array antenna18. In other words, the ring-shaped coupler22, the transmitting power divider12, and the transmitting array antenna18may be regarded as a transmitting microwave network in a microwave transceiver network.

Relatively for a receiving operation, the receiving power divider14receives radio-frequency signals sensed by the receiving array antenna20through input terminals IP1, IP2, and IP3, and respectively distributes the radio-frequency signals to output terminals OP5, OP6with a relationships of a second power ratio and a third power ratio. The ring-shaped couplers24,26may convert signals of the output terminals OP5, OP6to a first differential receiving signal and a second differential receiving signal and transmit the first and second differential receiving signals to the radio-frequency processing unit16for performing a signal processing of the radio-frequency signals by the radio-frequency processing unit16. In other words, the ring-shaped couplers24,26, the receiving power divider14, and the receiving array antenna20may be regarded as a receiving microwave network in the microwave transceiver network.

Moreover, the first power ratio (i.e. the power ratio from the input terminal IPTx to the output terminals OP1-OP4) complies with a relationship of (0.001˜0.1):1:1:(0.001˜0.1). In other words, power of the transmitting signals is mostly distributed to the output terminals OP2, OP3, and meanwhile, a phase of the signals of the output terminals OP1, OP2and a phase of the signals of the output terminals OP3, OP4are inverse. In addition, the second power ratio (i.e. the power ratio of the input terminals IP1-IP3relative to the output terminal OP5) complies with a relationship of (1˜10):1:(0.001˜0.1), and the third power ratio (i.e. the power ratio of the input terminals IP1-IP3relative to the output terminal OP6) complies with a relationship of (0.001˜0.1):1:(1˜10). In other words, for the output terminal OP5, the radio-frequency signals are mainly transmitted from the input terminals IP1, IP2, and for the output terminal OP6, the radio-frequency signals are mainly transmitted from the input terminals IP2, IP3. Therefore, the input terminal IP2may be regarded as a common signal source for the output terminals OP5and OP6. In short, the radio-frequency transceiver system10of the present invention mostly distributes power of the transmitting signals to the output terminals OP2, OP3by the transmitting power divider12, makes the phase of the signals of the output terminals OP1, OP2to be inverse to the phase of the signals of the output terminals OP3, OP4, and uses the receiving power divider14to let the output terminals OP5and OP6share the input terminal IP2.

For clear illustration, please refer toFIGS. 2A and 2B.FIGS. 2A and 2Brespectively illustrate schematic diagrams of the transmitting array antenna18and the transmitting power divider12inFIG. 1. As shown inFIG. 2A, the transmitting array antenna18includes four sub-arrays antennas180,182,184,186, which are respectively coupled to the output terminals OP1, OP2, OP3, OP4. In other words, an exciter or feed-in position of the transmitting array antenna18is at a side thereof, and a ground element G is disposed between the adjacent sub-array antennas to enhance isolation. In addition, each of the sub-array antennas180-186consists of eight radiating elements and connecting wires for connecting the eight radiating elements. A length of each radiating element and each connecting wire is substantially equal to a half wavelength of the transmitting signal, and widths of the radiating elements are monotonically decreased from a center to both sides of the sub-array antenna. Thus, an intensity distribution may be a same relationship (the strongest in the center and being monotonically decreased to the both sides), such that the power is gathered on an elevation plane to enhance an antenna gain and a side lobe suppression capability. Besides, the transmitting array antenna18totally utilizes the four sub-array antennas180-186and a wider beam may be achieved on an azimuth plane.

Furthermore, as shown inFIG. 2B, the transmitting power divider12mainly consists of ring-shaped transmission units120,122,124and connecting wires126and128. The ring-shaped transmission units120,122,124are three-terminal elements, which respectively consist of ground elements G1, G2, G3and ring-shaped conductive circles R1, R2, R3surrounding the ground elements G1, G2, G3. In detail, in the ring-shaped transmission unit120, the ring-shaped conductive circle R1is electrically connected to the input terminal IPTx and the connecting wires126and128, and a distance from the input terminal IPTx to the connecting wire126is substantially equal to a distance from the input terminal IPTx to the connecting wire128. A width of the ring-shaped conductive circle R1is substantially fixed to or close to a certain value. In such a condition, the ring-shaped transmission unit120is an equal power divider. In the ring-shaped transmission unit122, the ring-shaped conductive circle R2is electrically connected to the output terminals OP1, OP2and the connecting wire126. The ring-shaped conductive circle R2consists of six segments SEG_11-SEG_16and a length of each segment SEG_11-SEG_16is substantially equal to a quarter wavelength of the transmitted signal. Beside, in the ring-shaped transmission unit124, the ring-shaped conductive circle R3is electrically connected to the output terminals OP3and OP4and the connecting wire128. The ring-shaped conductive circle R3consists of six segments SEG_21-SEG_26and a length of each segment SEG_21-SEG_26is substantially equal to a quarter wavelength of the transmitted signal. Additionally, in the transmitting power divider12, the black blocks are represented as resistors for adjusting impedances.

Comparing the ring-shaped transmission unit122and the ring-shaped transmission unit124may show that the ring-shaped transmission unit124and the ring-shaped transmission unit122are symmetrical in accordance with a division between the output terminal OP2and the output terminal OP3, so as to generate inverse signal phases at the output terminals OP3, OP4and at the output terminals OP1, OP2. Thus, a null may be generated near the zero degree. In addition, the segments SEG_11-SEG_16and the segments SEG_21-SEG_26are wide and narrow alternately. In other words, based upon the widths of the segments, the segments SEG_11-SEG_16and the segments SEG_21-SEG_26may be divided into multiple groups. The transmitting power divider12may achieve a weighting distribution by arranging the segments of the different widths. For example, since the widths of the segments SEG_11, SEG_21are significantly smaller than the widths of the segments SEG_12, SEG_22, power may be mostly distributed to the output terminals OP2and OP3of the inner side (i.e. the sub-array antennas182and184). In other words, the transmitting power divider12is a two-stage five-port unequal power divider for gathering the main power for the output terminals OP2and OP3of the inner side and generating the inverse phases between the output terminals OP1, OP2and the output terminals OP3, OP4, to induce the null near the zero degree, so as to achieve a wider scanning angle on the azimuth plane.

Please refer toFIGS. 3A and 3B, which illustrate schematic diagrams of a receiving array antenna20and a receiving power divider14inFIG. 1. As shown inFIG. 3A, the receiving array antenna20includes three sub-arrays antennas200,202,204, which are respectively coupled to the input terminals IP1, IP2, IP3. The configuring methods of radiating elements and connecting wires for connecting the radiating elements of the sub-array antennas200,202,204are similar to the sub-array antennas180-186, and since widths of the radiating elements are similarly monotonically decreased from a center to both sides of the sub-array antenna, the working methods are also similar and will not be narrated hereinafter.

Furthermore, as shown inFIG. 3B, the receiving power divider14mainly consists of ring-shaped transmission units140,142,144and connecting wires146,148. The ring-shaped transmission units140,142,144are three-terminal elements, which respectively consist of ground elements G4, G5, G6and ring-shaped conductive circles R4, R5, R6surrounding the ground elements G4, G5, G6. In detail, in the ring-shaped transmission unit140, the ring-shaped conductive circle R4is electrically connected to the input terminal IP2and the connecting wires146,148, and a distance from the input terminal IP2to the connecting wire146is substantially equal to a distance from the input terminal IP2to the connecting wire148. A width of the ring-shaped conductive circle R4is substantially fixed to or close to a certain value. In such a condition, the ring-shaped transmission unit140is an equal power divider. In the ring-shaped transmission unit142, the ring-shaped conductive circle R5is electrically connected to the output terminal OP5, the input terminal IP1, and the connecting wire146, and the ring-shaped conductive circle R5consists of two segments SEG_31, SEG_32. Besides, in the ring-shaped transmission unit144, the ring-shaped conductive circle R6is electrically connected to the output terminal OP6, the input terminal IP3, and the connecting wire148, and the ring-shaped conductive circle R6consists of two segments SEG_41, SEG_42. Additionally, in the transmitting power divider14, the black blocks are represented as resistors for adjusting impedances.

Widths of the segments SEG_31, SEG_32, SEG_41, SEG_42(or a width ratio of the segments SEG_31, SEG_32, and a width ratio of the segments SEG_41, SEG_42) are related to a power ratio of the input terminals IP1-IP3relative to the output terminals OP5, OP6. More specifically, since the widths of the segments SEG_31, SEG_41are smaller than the widths of the segments SEG_32, SEG_42, and the ring-shaped transmission unit140equally distributes signal power of the input terminal IP2to the ring-shaped transmission units142,144, the power ratio of the input terminals IP1-IP3relative to the output terminals OP5may comply with a relationship of (1˜10):1:(0.001˜0.1), and the power ratio of the input terminals IP1-IP3relative to the output terminals OP6complies with a relationship of (0.001˜0.1):1:(1˜10). In other words, the main power of the output terminal OP5is contributed from the input terminals IP1, IP2, and the main power of the output terminal OP6is contributed from the input terminals IP2, IP3, wherein the input terminal IP2(or the sub-array antenna202) is shared, and the required areas of the sub-array antennas may be reduced. Therefore, for the receiving route from the output terminal OP5through the ring-shaped coupler24to the radio-frequency processing unit16, the main signal power is provided from the input terminals IP1, IP2(i.e. the sub-array antenna202,202); for the receiving path from the output terminal OP6through the ring-shaped coupler26to the radio-frequency processing unit16, the main signal power is provided from the input terminals IP2, IP3(i.e. the sub-array antenna202,204).

Besides, please refer toFIG. 4, which illustrates a schematic diagram of the ring-shaped coupler24inFIG. 1. Since the structures of the ring-shaped couplers22,24,26are the same, only the ring-shaped couple24, as a representation, is shown. The ring-shaped couplers22,24,26may convert the differential signals to the single-ended signals to meet a processing requirement of the radio-frequency processing unit16. In addition, in the ring-shaped coupler24, the black block is represented as a resistor for adjusting impedance.

As can be seen, the radio-frequency transceiver system10distributes most power of the transmitting signals to the inner sub-array antennas182,184, and generates the inverse phases between the sub-array antennas180,182and the sub-array antennas184,186to generate the null near the zero degree, so as to achieve the wider scanning angle on the azimuth plane. Besides, the radio-frequency transceiver system10uses the receiving power divider14to provide the main power of the output terminal OP5from the input terminals IP1, IP2, and provide the main power of the output terminal OP6from the input terminals IP2, IP3; that is, the sub-array antenna202is shared, and the required areas of the sub-array antennas may be reduced. Please refer toFIG. 5, which illustrates a schematic diagram of a two-dimensional antenna radiation pattern of the radio-frequency transceiver system10. InFIG. 5, the solid curve is represented as an antenna radiation pattern under transmission, the dotted curve is represented as an antenna radiation pattern of the output terminal OP5, and the dashed curve is represented as an antenna radiation pattern of the output terminal OP6. As can be seen, when the transmitting signals are transmitted, since the transmitting power divider12may generate the signals with the inverse phases, the null is generated at the zero degree on the azimuth plane to obtain the wider detecting angle. The radiation pattern under receiving is symmetrical to the zero degree, and the signals from the left and right sides are respectively received to facilitate to increase the scanning angle.

In addition, each component of the radio-frequency transceiver system10is disposed on the same plane. In other words, a via hole is not required to serve as the transmission of the signals for a critical connection to avoid frequency shift and antenna performance degradation caused by a process inaccuracy of wiring between different layers. Thus, only a single-layer high frequency circuit board is required to achieve a high antenna gain and increase the detecting angle, and further reduce the manufacturing cost.

In summary, the radio-frequency transceiver system of the present invention may effectively enhance an array antenna gain, reduce an array antenna area, optimize an antenna radiation pattern, reduce a reflection loss, and enhance a side lobe suppression capability.