Slot coupling feed type phased array film antenna with correction function

Abstract

The invention relates to a slot coupling feed type phased array film antenna with a correction function, and belongs to the field of phased array technology antennas. Comprising a phased array film antenna composed of a patch film layer, a gap film layer, a feed film layer and a radio frequency connector, and is characterized by further comprising a correction structure; the correction structure comprises a coupling line, a correction line, a correction through hole, a grounding line and a correction radio frequency connector. And the coupling line is linearly arranged on the patch film layer and penetrates through more than two rows of microstrip patches. The correction line and the correction through hole are arranged on the gap film layer and vertically correspond to the internal end of the coupling line. And the correction line and the grounding line are arranged on the feed film layer and vertically correspond to the coupling slot. The correction through hole is connected with the grounding wire through a metal wire. And inner and outer conductors of the correction radio frequency connector are respectively connected with the correction line and the connector. And the correction structure realizes random phase error correction adjustment of the feed system of the phased array film antenna.

Description

Technical Field

[0001] The present invention belongs to the field of phased array technology antennas, and particularly relates to a slotted-coupled-fed phased array thin-film antenna with a calibration function. Background Art

[0002] Thin-film antennas can be used to realize high-gain and large-aperture lightweight deployable antennas, and have important applications in fields such as earth communication, earth observation, land remote sensing, deep space exploration and communication. Such lightweight antennas are of great significance for reducing weight and cost.

[0003] A typical implementation method is to use a microstrip patch antenna structure, where the antenna is divided into layers such as a patch layer, a slot layer, a feeding layer, and a reflection layer, which are printed on different thin films respectively, and then combined through a support structure. According to specific applications, by adding a patch layer and a reflection layer, this structure can be extended to a more complex structure.

[0004] In a phased array antenna system, due to the processing, installation tolerances of various feeder components, component replacement, and the influence of the surrounding environmental temperature, there are quite large random phase errors in the phased array antenna feeding system. The failure and instability of active devices will deteriorate the antenna performance. To maintain the antenna performance, the system must have amplitude-phase monitoring and calibration capabilities. If these errors are not calibrated, they will seriously damage the antenna pattern characteristics, resulting in a decrease in antenna gain, a deterioration in sidelobe level, and a decrease in beam pointing accuracy.

[0005] The common calibration methods for phased array antennas can be divided into internal calibration and external calibration. External calibration is completed with the help of a darkroom probe and an auxiliary antenna. Its advantages are a small amount of equipment and the ability to calibrate the antenna inconsistency. The disadvantage is poor calibration accuracy and susceptibility to external influences. The internal calibration method introduces a calibration network between the antenna and the RF components. Its advantage is high calibration accuracy, and the disadvantage is a large amount of equipment. To achieve reliable calibration, the internal calibration method is often used, where the transmission ports of the calibration network are embedded between the antenna and the active components, and coupled energy is transmitted or received at the coupling ports. If the structure of the antenna system itself cannot be used to design the calibration network, additional volume and weight will be introduced.

[0006] For a multi-layer phased array antenna in non-film form, a section of transmission line can be added at the antenna input port as a coupling line, and several coupling lines are connected to form a calibration network. However, in the context of thin-film antennas, it is quite difficult to implement a calibration network. First of all, thin-film antennas pursue light weight and have strict requirements for weight. The calibration network should be implemented on the existing multi-layer thin films without adding extra thin films or microstrip boards. Secondly, in order to achieve the distribution and synthesis of the energy of the antenna array surface, there are various feeding networks in the feeding layer. And the layout of the feeding network restricts the space of the calibration network to a certain extent, requiring the calibration network to be as small as possible. Existing literature does not mention the thin-film antenna scheme with an integrated calibration network. Summary of the Invention

[0007] In order to embed a lightweight calibration network structure in a thin-film antenna, the present invention provides a slotted-coupled-fed phased array thin-film antenna with a calibration function.

[0008] A slotted-coupled-fed phased array thin-film antenna with a calibration function includes a phased array thin-film antenna composed of a patch thin-film layer 1, a slot thin-film layer 3, a feeding thin-film layer 7, and a radio frequency connector 8; An upper foam layer 2 is provided between the patch thin-film layer 1 and the slot thin-film layer 3, and a lower foam layer 6 is provided between the slot thin-film layer 3 and the feeding thin-film layer 7; Two rows of microstrip patches 12 are evenly distributed on the top surface of the patch thin-film layer 1; Corresponding to the two rows of microstrip patches 12 up and down, two rows of antenna slots 31 are evenly opened on the top surface of the slot thin-film layer 3; Corresponding to the two rows of microstrip patches 12 up and down, feeding structures are evenly provided on the bottom surface of the feeding thin-film layer 7, and a T-shaped grounding wire 72 is also provided on the bottom surface of the feeding thin-film layer 7; It further includes a calibration structure; The calibration structure includes a coupling line 11, a group of calibration slots, a group of calibration through holes, a calibration line 73, a grounding wire 74, and a calibration radio frequency connector 9; a group of calibration slots consists of three parallel calibration slots (33), and a group of calibration through holes consists of three calibration through holes (34); The coupling line 11 is linearly arranged on the top surface of the patch thin-film layer 1 and penetrates between adjacent two rows of microstrip patches 12; the antenna end 111 of the coupling line 11 is located at one side edge of the patch thin-film layer 1, and the inner end 112 of the coupling line 11 is located at the other side of the patch thin-film layer 1; The group of calibration slots is arranged on the slot thin-film layer 3, the group of calibration slots corresponds to the inner end 112 of the coupling line 11 up and down, and the three calibration slots 33 are perpendicular to the coupling line 11; the group of calibration through holes is opened on the slot thin-film layer 3 outside the group of calibration slots; The correction line 73 is arranged on the bottom surface of the feeding film layer 7, the correction line 73 is parallel to the coupling line 11, and the correction line 73 is located below the inner end of the coupling line 11; the correction line 73 and the grounding line 74 are on a straight line, and a gap is provided between the correction line 73 and the grounding line 74; A set of correction slits realizes the transmission energy between the coupling line 11 and the correction line 73; The outer conductor of the correction RF connector 9 is connected to the correction connection through hole 742 of the ground line 74, and the inner conductor of the correction RF connector 9 is connected to the ground end 734 of the correction line 73; The correction structure realizes random phase error correction and adjustment of the feeding system of the phased array film antenna.

[0009] The further technical solution is as follows: The intervals between adjacent correction slits 33 in the group of correction slits 33 are equal.

[0010] One end of the correction line 73 opposite to the microstrip patch 12 is the inner end, and the inner end is a small fan-shaped end 731. The end of the correction line 73 opposite to the grounding line 74 is the outer end, and the end of the outer end is provided with a wiring terminal 734, and correction branch lines 733 are respectively provided on both sides of the outer end; the correction line 73 between the inner end and the outer end is radially provided with a pair of correction fan-shaped pieces 732; the grounding line 74 is provided with three joint ends, one end of the three joint ends is connected in parallel, and the other end of the three joint ends is respectively provided with wiring rings 741; the wiring terminal 734 of the correction line 73 corresponds to the parallel connection of the three joint ends of the grounding line 74; the three correction through holes 34 on the gap film layer 3 and the ring holes of the corresponding wiring rings 741 on the bottom surface of the feeding film layer 7 are connected by a correction metal wire 5.

[0011] The correction branch line 733 is an L-shaped line.

[0012] The phased array film antenna array is composed of more than two rows of phased array film antennas arranged in parallel along a direction perpendicular to the coupling line; it includes more than two coupling lines 11, more than two correction lines 73, a ground line 74 and a correction RF connector 9; the correction structure connects more than two correction lines 73 in parallel through a power division network 735, and connects them to a ground terminal 734.

[0013] The beneficial technical effects of the present invention are embodied in the following aspects: 1. The present invention adds a calibration network structure to the structure of a typical phased array thin film antenna, achieving an integrated design without adding additional thin films, dielectrics, support structures, and loads. By adopting the same three-layer thin film framework as the antenna element, the calibration network can be parasitically integrated into the antenna array. Using the same principle as the antenna element feeding, coupling lines, calibration slots, and calibration lines are designed on the patch thin film layer, slot thin film layer, and feeding thin film layer respectively, enabling the transmission of microwave signals between the three thin films. One side of the calibration line is connected to a calibration RF connector to form an external microwave signal interface. The coupling line is inserted into the antenna array, and the coupling amount can be controlled by adjusting the width of the coupling line and the distance between the coupling line and the microstrip patch. When the coupling amount is appropriate, its intensity not only meets the calibration requirements but also does not affect the performance of the antenna. Thus, an integrated design of the structure and function of the antenna and the calibration network is achieved.

[0014] 2. The present invention improves the matching performance of the calibration network through the design of the coupling line in the patch layer, the slot structure in the slot layer, and the transmission structure in the feeding layer. When calibrating the antenna, within a 7% bandwidth, a standing wave of no more than 2.1 and a coupling degree of about -35 dB are achieved.

[0015] 3. The technical solution of the calibration network structure of the present invention is extended to antenna arrays of various scales through a power distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the phased array thin film antenna structure of the present invention.

[0017] Figure 2 is Figure 1 exploded view of.

[0018] Figure 3 is Figure 1 bottom view of.

[0019] Figure 4 Schematic diagram of the patch thin film layer structure.

[0020] Figure 5 is Figure 4 enlarged view of.

[0021] Figure 6 Schematic diagram of the slot thin film layer structure.

[0022] Figure 7 Bottom view schematic diagram of the feeding thin film layer.

[0023] Figure 8 Schematic diagram of the feeder structure of the antenna.

[0024] Figure 9 Schematic diagram of the calibration line structure.

[0025] Figure 10 isFigure 9 Partial enlarged view.

[0026] Figure 11 It is the coupling degree diagram of Embodiment 1.

[0027] Figure 12 It is the standing wave diagram of Embodiment 1; (a) Calibrated RF connector port (b) RF connector end.

[0028] Figure 13 It is the radiation pattern of Embodiment 1.

[0029] Figure 14 It is the structural schematic diagram of Embodiment 2.

[0030] Figure 15 It is the bottom view of Embodiment 2.

[0031] Figure 16 It is the schematic diagram of the power distribution network.

[0032] Figure 17 It is the coupling diagram of Embodiment 2.

[0033] Figure 18 It is the standing wave diagram of Embodiment 2; (a) Calibrated RF connector port (b) RF connector end.

[0034] Figure 19 It is the radiation pattern of Embodiment 2.

[0035] Figure 20 It is the structural schematic diagram of Embodiment 3.

[0036] The serial numbers in the above figure: patch thin film layer 1, upper foam layer 2, slit thin film layer 3, antenna wire 4, calibration wire 5, lower foam layer 6, feed thin film layer 7, RF connector 8, calibrated RF connector 9, coupling line 11, antenna end 111, internal end 112, microstrip patch 12, antenna slit 31, antenna through hole 32, calibration slit 33, calibration through hole 34, antenna feeder 71, antenna feeder stub 711, T-shaped ground wire 72, ground ring 721, connector through hole 722, calibration line 73, small fan-shaped end 731, calibration fan-shaped piece 732, calibration stub line 733, connection terminal 734, power distribution network 735, ground wire 74, connection ring 741, calibration connection through hole 742. Specific implementation manners

[0037] The present invention will be further described below with reference to the accompanying drawings through embodiments. Embodiment 1

[0038] See Figure 1 and Figure 2, A phased array thin-film antenna with a correction function using slot-coupled feeding includes a patch thin-film layer 1, a slot thin-film layer 3, a feeding thin-film layer 7, a radio frequency connector 8, and a correction structure.

[0039] See Figure 2 , An upper foam layer 2 is provided between the patch thin-film layer 1 and the slot thin-film layer 3, and a lower foam layer 6 is provided between the slot thin-film layer 3 and the feeding thin-film layer 7.

[0040] See Figure 4 , Two rows of microstrip patches 12 are evenly distributed on the top surface of the patch thin-film layer 1, and the microstrip patches 12 are rectangular patches.

[0041] See Figure 6 , Corresponding to the two rows of microstrip patches 12 up and down, two rows of antenna slots 31 and antenna through-holes 32 are evenly distributed on the top surface of the slot thin-film layer 3; See Figure 2 、 Figure 6 and Figure 8 , The antenna through-hole 32 is connected to the loop hole of the grounding ring 721 on the bottom surface of the corresponding feeding thin-film layer 7 through an antenna wire 4. Corresponding to the two rows of microstrip patches 12 up and down, an antenna feeding structure is evenly distributed on the bottom surface of the feeding thin-film layer 7, and a T-shaped grounding wire 72 is also provided.

[0042] See Figure 7 , The antenna feeding structure includes two groups of antenna feed lines. The two groups of antenna feed lines correspond to the two rows of microstrip patches 12 up and down respectively. Each group of antenna feed lines is composed of several antenna feed line units evenly distributed on a straight line. The antenna feed line unit is composed of an antenna feed line 71 and a T-shaped grounding wire 72 on a straight line.

[0043] See Figure 8 , The T-shaped grounding wire 72 has three joint ends. One ends of the three joint ends are connected in parallel, and grounding rings 721 are respectively provided at the other ends of the three joint ends. A connector through-hole 722 is provided on the T-shaped grounding wire 72 between the adjacent parallel joint ends. One end of the antenna feed line 71 opposite to the T-shaped grounding wire 72 is respectively connected to the antenna feed line branches 711 on both sides.

[0044] The radio frequency connector 8 is located below the feeding thin-film layer 7. Its inner conductor is connected to the antenna feed line 71, and the outer conductor is connected to the T-shaped grounding wire 72.

[0045] The correction structure includes a coupling line 11, a correction line 73, a grounding wire 74, a group of correction slots, a group of correction through-holes, and a correction radio frequency connector 9. The group of correction slots consists of three correction slots 33, and the group of correction through-holes consists of three correction through-holes 34.

[0046] See Figure 4 , The coupling line 11 is linear and is provided on the top surface of the patch thin-film layer 1 and penetrates between the adjacent two rows of microstrip patches 12. SeeFigure 5 , the antenna end 111 of the coupling line 11 is located at one side edge of the patch thin film layer 1, and the inner end 112 of the coupling line 11 is located at the other side of the patch thin film layer 1.

[0047] See Figure 6 , a group of calibration slits are opened in the slit thin film layer 3. The distance between adjacent calibration slits 33 in the group of calibration slits is equal, and the three calibration slits 33 are perpendicular to the coupling line 11. Three calibration through holes 34 are opened on the slit thin film layer 3 outside the group of calibration slits. See Figure 2 , a group of calibration slits correspond to the inner end 112 of the coupling line 11 up and down.

[0048] See Figure 7 , the calibration line 73 is arranged on the bottom surface of the feed thin film layer 7. The calibration line 73 is parallel to the coupling line 11 up and down, and the calibration line 73 is located below the inner end of the coupling line 11; the calibration line 73 and the ground wire 74 are on a straight line, and there is a gap between the calibration line 73 and the ground wire 74. See Figure 2 , above the calibration line 73 corresponds to a group of calibration slits on the slit thin film layer 3; a group of calibration slits realize the transmission energy between the coupling line 11 and the calibration line 73; the three calibration through holes 34 and the ring holes of the corresponding wiring rings 741 are connected by calibration metal wires 5.

[0049] See Figure 9 , one end of the calibration line 73 opposite to the microstrip patch 12 is the inner end, the inner end is a small fan-shaped end 731, one end of the calibration line 73 opposite to the ground wire 74 is the outer end, a wiring end 734 is provided at the end of the outer end, and calibration branch lines 733 are respectively provided on both sides of the outer end. The calibration branch lines 733 are L-shaped lines. A pair of calibration fan-shaped pieces 732 are provided on the radial direction of the calibration line 73 between the inner end and the outer end of the calibration line 73. See Figure 10 , the ground wire 74 is provided with three joint ends. One ends of the three joint ends are connected in parallel, and the other ends of the three joint ends are respectively provided with wiring rings 741. The wiring end 734 of the calibration line 73 corresponds to the parallel connection part of the three joint ends of the ground wire 74; the three calibration through holes 34 on the slit thin film layer 3 and the ring holes of the corresponding wiring rings 741 on the bottom surface of the feed thin film layer 7 are connected by calibration metal wires 5.

[0050] Calibration connector through holes 742 are opened on the ground wire 74 between adjacent parallel joint ends.

[0051] See Figure 9 , the outer conductor of the calibration RF connector 9 is connected to the calibration connection through hole 742 of the ground wire 74, and the inner conductor of the calibration RF connector 9 is connected to the grounding end 734 of the calibration line 73.

[0052] The phased array thin-film antenna of Embodiment 1 is an antenna unit that scans one-dimensionally along the X direction. In the transmission calibration state, an external transmission device feeds a microwave signal into the RF connector 8. This microwave signal is sequentially transmitted to the antenna feeder 71, the antenna slot 31, the microstrip patch 12, the coupling line 11, a group of calibration slots, the calibration line 73, and the calibration RF connector 9. Finally, the external receiving device receives the microwave signal at the calibration RF connector 9. By comparing the amplitude and phase with a path signal, the random amplitude and phase errors of the RF channel corresponding to the RF connector 8 are corrected.

[0053] In the receiving calibration state, the external transmission device feeds a microwave signal into each calibration RF connector 9. This microwave signal is sequentially transmitted to the calibration line 73, a group of calibration slots, the coupling line 11, the microstrip patch 12, the antenna slot 31, the antenna feeder 71, and the RF connector 8. Finally, the external receiving device receives the microwave signal at the calibration RF connector 9. By comparing the amplitude and phase with a path signal, the random amplitude and phase errors of the RF channel corresponding to the RF connector 8 are corrected.

[0054] In the receiving state, the incoming space microwave signal sequentially passes through the microstrip patch 12, the antenna slot 31, the antenna feeder 71, and the RF connector 8 to reach the external receiving device.

[0055] In the transmitting state, the microwave signal from the external transmission device is sequentially radiated into space through the RF connector 8, the antenna feeder 71, the antenna slot 31, and the microstrip patch 12.

[0056] See Figure 11 , in Embodiment 1, within the operating frequency band with a relative bandwidth of about 7%, the coupling degree is between -22.5 dB and -45 dB.

[0057] See Figure 12 A in, in Embodiment 1, within the operating frequency band with a relative bandwidth of about 7%, the standing wave ratio of the calibration port is better than 2.1; see Figure 12 B in, in Embodiment 1, within the operating frequency band with a relative bandwidth of about 7%, the standing wave ratio of the antenna port is better than 1.6.

[0058] See Figure 13 , for the intermediate frequency radiation pattern of Embodiment 1, the gain is about 20 dB. Embodiment 2

[0059] See Figure 14 , the phased array thin-film antenna array is composed of four phased array thin-film antennas of Embodiment 1 arranged side by side perpendicular to the coupling line direction, realizing an antenna array for two-dimensional scanning.

[0060] See Figure 14 , on the top surface of the patch thin-film layer 1, eight rows of microstrip patches 12 and four coupling lines 11 are evenly distributed, and the microstrip patches 12 are rectangular patches.

[0061] See Figure 15 , on the bottom surface of the feeding thin film layer 7, four calibration lines 73 and a grounding line 74 are provided corresponding to the inner ends 112 of the coupling lines 11 on the patch thin film layer 1 up and down.

[0062] The calibration structure includes four coupling lines 11, four calibration lines 73, a grounding line 74, four groups of calibration slits and a calibration RF connector 9. See Figure 16 , the four calibration lines 73 are connected in parallel to a grounding end 734 through a power dividing network 735.

[0063] Other structures are the same as those in Embodiment 1.

[0064] During the reception calibration operation, the microwave signal is transmitted from an external device, and successively passes through the calibration RF connector 9, the calibration line 73, the power dividing network 735, the four groups of calibration slits, and the coupling line 11 to reach the antenna array. During the transmission calibration operation, the microwave signal is transmitted from the microstrip patch 12, and successively passes through the coupling line 11, the four groups of calibration slits, the calibration line 73, the power dividing network 735, and the calibration RF connector 9 to reach the external device; the random amplitude and phase errors of the antenna array in this Embodiment 2 are respectively corrected.

[0065] See Figure 17 , for the antenna array in this Embodiment 2, within the operating frequency band with a relative bandwidth of about 3.6%, the coupling degree is between -30 dB and -45 dB.

[0066] See Figure 18 , for the antenna array in this Embodiment 2, within the operating frequency band with a relative bandwidth of about 3.6%, the standing wave ratio of the calibration port is better than 2.0; within the operating frequency band with a relative bandwidth of about 3.6%, the standing wave ratio of the antenna port is better than 1.8.

[0067] See Figure 19 , for the intermediate frequency radiation pattern of the antenna array in this Embodiment 2, the gain is about 26 dB. Embodiment 3

[0068] This Embodiment 3 is the variation of the antenna element in Embodiment 1. See Figure 20 , the microstrip patch 12 is a circular patch, and other structures are the same as those in Embodiment 1.

Claims

1. A slot-coupled fed phased array film antenna with a correction function, comprising a phased array film antenna consisting of a patch film layer (1), a slot film layer (3), a feed film layer (7) and a radio frequency connector (8); an upper foam layer (2) is provided between the patch film layer (1) and the slot film layer (3), and a lower foam layer (6) is provided between the slot film layer (3) and the feed film layer (7); two rows of microstrip patches (12) are evenly arranged on the top surface of the patch film layer (1); two rows of antenna slots (31) are evenly arranged on the top surface of the slot film layer (3) corresponding to the two rows of microstrip patches (12); a feed structure is evenly arranged on the bottom surface of the feed film layer (7) corresponding to the two rows of microstrip patches (12); and a T-shaped ground wire (72) is also provided; Features: It also includes correction structures; The correction structure comprises a coupling line (11), a group of correction slits, a group of correction through holes, a correction line (73), a ground line (74) and a correction radio frequency connector (9); the group of correction slits is composed of three parallel correction slits (33), and the group of correction through holes is composed of three correction through holes (34); The coupling line (11) is in a straight line shape, is disposed on the top surface of the patch film layer (1), and runs through between two adjacent rows of microstrip patches (12); the antenna end (111) of the coupling line (11) is located at one edge of the patch film layer (1), and the inner end (112) of the coupling line (11) is located on the other side of the patch film layer (1); The group of correction slits is arranged on the gap film layer (3), the group of correction slits corresponds to the inner end (112) of the coupling line (11) up and down, and the three correction slits (33) are perpendicular to the coupling line (11); a group of correction through holes is opened on the gap film layer (3) outside the group of correction slits; The correction line (73) is arranged on the bottom surface of the feeding film layer (7), the correction line (73) and the coupling line (11) are parallel and correspond to each other, and the correction line (73) is located below the inner end of the coupling line (11); the correction line (73) and the grounding line (74) are on a straight line, and a gap is provided between the correction line (73) and the grounding line (74); A set of correction slits realizes the transmission of energy between the coupling line (11) and the correction line (73); The outer conductor of the correction radio frequency connector (9) is connected to the correction connection through hole (742) of the ground line (74), and the inner conductor of the correction radio frequency connector (9) is connected to the ground end (734) of the correction line (73); The correction structure realizes random phase error correction and adjustment of the feeding system of the phased array film antenna.

2. According to claim 1, a slot-coupled-fed phased array film antenna with correction function, characterized in that: The spacing between adjacent correction slits (33) in the group of correction slits (33) is equal.

3. According to claim 1, a slot-coupled-fed phased array film antenna with correction function, characterized in that: One end of the correction line (73) opposite to the microstrip patch (12) is an inner end, the inner end is a small fan-shaped end (731), and one end of the correction line (73) opposite to the grounding line (74) is an outer end, the end of the outer end is provided with a wiring terminal (734), and correction branch lines (733) are respectively provided on both sides of the outer end; the correction line (73) between the inner end and the outer end is provided with a pair of correction fan-shaped pieces (732) in the radial direction; the grounding line (74) is provided with three joint ends, one end of the three joint ends is connected in parallel, and the other end of the three joint ends is respectively provided with a wiring ring (741); the wiring terminal (734) of the correction line (73) corresponds to the parallel connection of the three joint ends of the grounding line (74); the three correction through holes (34) on the gap film layer (3) and the ring holes of the corresponding wiring ring (741) on the bottom surface of the feeding film layer (7) are connected by a correction metal wire (5).

4. The slot-coupled-fed phased array film antenna with correction function according to claim 3, characterized in that: The correction branch line (733) is an L-shaped line.

5. A phased array film antenna array based on the slot-coupled fed phased array film antenna with correction function as claimed in claims 1-4, characterized in that: The phased array thin film antenna array is composed of more than two rows of phased array thin film antennas arranged in parallel along a direction perpendicular to the coupling line; it includes more than two coupling lines (11), more than two correction lines (73), a ground line (74) and a correction radio frequency connector (9); the correction structure connects the more than two correction lines (73) in parallel through a power division network (735), and connects them together to a ground terminal (734).

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