Double-frequency four-arm helical antenna

Abstract

The double-frequency four-arm helical antenna comprises a first frequency band helical antenna arm which comprises four groups of helical antenna arms, each group of helical antenna arms comprises a main radiation arm and a parasitic radiation arm, and the pitch angle of the main radiation arm is larger than the pitch angle of the parasitic radiation arm so as to broaden the antenna bandwidth; the length of the main radiation arm is larger than that of the parasitic radiation arm, and the arm width of the main radiation arm is gradually increased from the area, close to the connecting feed arm, of the main radiation arm to the area, away from the connecting feed arm, of the main radiation arm, and the arm width of the parasitic radiation arm is gradually increased.

Description

Technical Field

[0001] This application relates to the field of communications, and more particularly, to a dual-band four-arm helix antenna. Background Art

[0002] Currently, the relatively narrow operating frequency band of the dual-band four-arm helix antenna has been restricting the application of the antenna on small ground terminal devices. Summary of the Invention

[0003] This application provides a dual-band four-arm helix antenna, comprising: a first-band helix antenna arm, which includes four groups of helix antenna arms, each group of helix antenna arms includes a main radiation arm and a parasitic radiation arm, and the pitch angle of the main radiation arm is greater than that of the parasitic radiation arm to broaden the antenna bandwidth, and the length of the main radiation arm is greater than that of the parasitic radiation arm, and from the region where the main radiation arm is close to the connection feed arm to the region where the main radiation arm is far from the connection feed arm, the arm width of the main radiation arm gradually increases and the arm width of the parasitic radiation arm gradually increases, where the pitch angle is the angle between the main radiation arm and the connection feed arm, the connection feed arm connects the main radiation arm and the parasitic connection feed arm, and the arm width of the main radiation arm refers to the width of the main radiation arm in the extension direction of the length of the connection feed arm; a second-band helix antenna arm, which includes four groups of helix antenna arms, each group of helix antenna arms includes a wide arm, a first open stub, a second open stub, and a third open stub, and the length of the first open stub is greater than that of the second open stub, the length of the second open stub is greater than that of the third open stub, and the first open stub, the second open stub, and the third open stub are connected to a feed arm; the length of each helix antenna arm in the first-band helix antenna arm and the second-band helix antenna arm is an integer multiple of one-quarter of the wavelength, and the amplitudes of the currents in the feed sections of the first-band helix antenna arm and the second-band helix antenna arm are equal and the phases of the currents differ by 90 degrees in sequence; the dual-band four-arm helix antenna further includes a dielectric support column, which is a hollow cylinder, the dielectric support column is fixed on a metal support plate, and the first-band helix antenna arm is uniformly wound around the outside of the dielectric support column, and the second-band helix antenna arm is uniformly wound around the inside of the dielectric support column, and the first-band helix antenna arm and the second-band helix antenna arm are consistent in length in the extension direction of the axis of the dielectric support column.

[0004] The operating bandwidth of the above dual-band four-arm helix antenna will be significantly improved. Description of the Drawings

[0005] To better describe and illustrate the embodiments of this application, one or more drawings may be referred to, but the additional details or examples used to describe the drawings should not be considered as limiting the scope of any one of the inventions, the currently described embodiments, or the preferred modes of this application.

[0006] Figure 1It is a schematic diagram of a dual - frequency four - arm spiral antenna.

[0007] Figure 2 It is a plan view of the unfolded spiral antenna arm of the first frequency band.

[0008] Figure 3 It is a plan view of the unfolded spiral antenna arm of the second frequency band.

[0009] Figure 4 It is an embodiment of a single - stage RC - CR feeding network.

[0010] Figure 5 It is an embodiment of a multi - stage RC - CR feeding network.

[0011] Figure 6 It is another embodiment of a multi - stage RC - CR feeding network.

[0012] Figures 7 to 9 It is the working principle of the RC - CR feeding network. Detailed implementation manners

[0013] In order to make the purpose, technical solutions and advantages of this application clearer, the following further details this application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain this application and are not used to limit this application.

[0014] Figure 1 It is a schematic diagram of a dual - frequency four - arm spiral antenna. A four - arm spiral antenna includes a dielectric support column, a first - frequency - band spiral antenna arm, a second - frequency - band spiral antenna arm, a metal support plate and a feeding network. The four - arm spiral antenna includes four spiral antenna arms, and the length of each spiral antenna arm is an integer multiple of a quarter - wavelength. The current amplitudes of the feeding sections of the four spiral antenna arms are equal, and the phases differ by 90° in sequence. The dielectric support column is a hollow cylinder, and its dielectric constant ranges from 2.2 to 2.7. The dielectric support column is fixed on the metal support plate; the first - frequency - band spiral antenna arm is wound around the outside of the dielectric support column; the second - frequency - band spiral antenna arm is wound around the inside of the dielectric support column. The metal support plate is located below the dielectric support column and is used to fix the antenna and the PCB board; the metal support plate can isolate the spiral antenna arms of the antenna from the feeding network to ensure that the spiral antenna arms and the feeding network do not interfere with each other.

[0015] Figure 2 It is a plan view of the unfolded first - frequency - band spiral antenna arm. The first - frequency - band spiral antenna arm is evenly wound around the outside of the dielectric support column, and the height of the spiral antenna arm is the same as the height of the dielectric support column.

[0016] Each group of spiral antenna arms includes a main radiation arm and a parasitic radiation arm. The main radiation arm and the parasitic radiation arm are not parallel, and the lengths of the main radiation arm and the parasitic radiation arm are different. Among them, the pitch angle α of the main radiation arm 1Greater than the pitch angle α of the parasitic radiation arm 2 , for broadening the frequency band. The difference in pitch angles can reduce the coupling between the main radiation arm and the parasitic radiation arm. Therefore, the radiation performance of the antenna is improved, for example, the bandwidth is increased. The pitch angle is shown in Figure 2 , and is the included angle between the main radiation arm and the connecting feed arm, where the connecting feed arm can connect the main radiation arm and the parasitic connecting feed arm.

[0017] From the area of the main radiation arm close to the connecting feed arm to the area of the main radiation arm far from the connecting feed arm, the arm width of the main radiation arm gradually increases, and the arm width of the parasitic radiation arm gradually increases. Here, the arm width of the main radiation arm refers to the width of the main radiation arm in the extending direction of the length of the connecting feed arm. The gradual increase in the arm width of the radiation arm can improve the impedance characteristics of the antenna, thereby broadening the bandwidth of the antenna.

[0018] The resonant frequency corresponding to the main radiation arm and the resonant frequency corresponding to the parasitic radiation arm are both within the first frequency band, and the difference between the two resonant frequency points is small, thereby broadening the bandwidth of the first frequency band.

[0019] Figure 3 It is a planar view of the unfolded arms of the second-band spiral antenna. The second-band spiral antenna arms can include four groups. Each group of spiral antenna arms includes a wide arm and an open stub. The open stub can include three segments, namely, open stub 1, open stub 2, and open stub 3. The lengths of each segment of the open stub are different.

[0020] The resonant frequency point corresponding to open stub 1, the resonant frequency point corresponding to open stub 2, and the resonant frequency point corresponding to open stub 3 are all within the second frequency band, and the difference between the three resonant frequency points is small, thereby broadening the bandwidth of the second frequency band. Open stub 1, open stub 2, and open stub 3 are connected to a feed arm, and the input impedance of the spiral antenna is further adjusted through a circuit, thereby broadening the bandwidth of the antenna in the first frequency band and the second frequency band.

[0021] In one embodiment, a dual-band four-arm spiral antenna is provided, comprising: a first-band spiral antenna arm, which includes four groups of spiral antenna arms, each group of spiral antenna arms including a main radiation arm and a parasitic radiation arm, and the pitch angle of the main radiation arm being greater than that of the parasitic radiation arm to broaden the antenna bandwidth, and the length of the main radiation arm being greater than that of the parasitic radiation arm, and the arm width of the main radiation arm gradually increasing and the arm width of the parasitic radiation arm gradually increasing from the area where the main radiation arm is close to the connection feed arm to the area where the main radiation arm is far from the connection feed arm, wherein the pitch angle is the angle between the main radiation arm and the connection feed arm, the connection feed arm connecting the main radiation arm and the parasitic connection feed arm, and the arm width of the main radiation arm refers to the width of the main radiation arm in the extension direction of the length of the connection feed arm; a second-band spiral antenna arm, which includes four groups of spiral antenna arms, each group of spiral antenna arms including a wide arm, a first open stub, a second open stub, and a third open stub, and the length of the first open stub being greater than that of the second open stub, the length of the second open stub being greater than that of the third open stub, and the first open stub, the second open stub, and the third open stub being connected to a feed arm; the length of each spiral antenna arm in the first-band spiral antenna arm and the second-band spiral antenna arm being an integer multiple of a quarter of the wavelength, and the amplitudes of the currents in the feed sections of the first-band spiral antenna arm and the second-band spiral antenna arm being equal and the phases of the currents differing by 90 degrees in sequence; the dual-band four-arm spiral antenna further includes a dielectric support column, which is a hollow cylinder, the dielectric support column being fixed on a metal support plate, and the first-band spiral antenna arm being uniformly wound around the outside of the dielectric support column, and the second-band spiral antenna arm being uniformly wound around the inside of the dielectric support column, and the first-band spiral antenna arm and the second-band spiral antenna arm being consistent in length in the extension direction of the axis of the dielectric support column.

[0022] In another embodiment, the dual-band four-arm spiral antenna further includes a feed network, the feed network being a multi-stage RC-CR feed network, the multi-stage RC-CR feed network being cascaded by single-stage RC-CR feed networks, and the single-stage RC-CR feed network including 4 resistors and 4 capacitors.

[0023] Figure 4 is a single-stage RC-CR feed network. The single-stage RC-CR feed network is composed of 4 groups of inductors and 4 groups of capacitors. Figure 5 is a multi-stage RC-CR feed network. Multiple groups of single-stage RC-CR feed networks are cascaded, and the feed network outputs 4 groups of feed signals with equal amplitudes and phases differing by 90° in sequence within a wide frequency band. The input signal of the feed network can be a single-ended signal or a differential signal. Figure 6is another embodiment of a multi-stage RC-CR feeding network. The multi-stage RC-CR cascaded network technology can achieve an octave bandwidth, covering a first frequency band and a second frequency band. When it is desired to operate within a relatively wide frequency band, multiple stages of RC-CR networks can be added, where the frequency points of each stage of RC-CR network are different.

[0024] As Figure 7 shown, according to the sequence theory (basis function), for any phasor set of 4 input signals, it can be decomposed into the superposition of 4 types of sequences: orthogonal clockwise (C phasor), orthogonal counterclockwise (A phasor), collinear differential (B phasor), collinear in the same direction (D phasor), where the collinear differential and collinear in the same direction generate a common-mode component at the output. When a differential circuit is used in the system, the common-mode component can be suppressed, so only two components, orthogonal clockwise and orthogonal counterclockwise, need to be considered;

[0025] As Figure 8 shown, an RC network is constructed: when the input signal frequency is 1 / (2πRC), it moves -45 degrees and +45 degrees respectively when passing through the resistor and the capacitor. When the order of the 4 input signals is orthogonal counterclockwise (left side of the following figure), the phasor of each output node is formed by the superposition of two adjacent orthogonal input phasors after moving -45 degrees and 45 degrees respectively, and the phases are the same, so the phasor doubles; at the same time, the 4 outputs are still orthogonal signals; while for the 4 input signals being orthogonal clockwise (right side of the following figure), since the phases after superposition are inconsistent and are 180 degrees, that is, in the reverse direction, the energy will be eliminated, that is, the orthogonal clockwise cannot pass through this RC network.

[0026] As Figure 9 shown, according to the above principle, a differential signal can be decomposed into 4 paths of orthogonal counterclockwise and 4 paths of orthogonal clockwise, and after passing through the above RC network, 4 paths of orthogonal signals are generated. When it is desired to operate within a relatively wide frequency band, multiple stages of RC networks can be added, where the frequency points of each stage of RC network are different.

[0027] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0028] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A dual-frequency four-arm helical antenna, comprising: A first frequency band helical antenna arm, comprising four groups of helical antenna arms, each group of helical antenna arms comprising a main radiating arm and a parasitic radiating arm, and a pitch angle of the main radiating arm is greater than a pitch angle of the parasitic radiating arm to widen the antenna bandwidth, and a length of the main radiating arm is greater than a length of the parasitic radiating arm, and an arm width of the main radiating arm gradually increases from an area where the main radiating arm is close to a connection feed arm to an area where the main radiating arm is far from the connection feed arm, and an arm width of the parasitic radiating arm gradually increases, wherein the pitch angle is an angle between the main radiating arm and the connection feed arm, the connection feed arm connects the main radiating arm and the parasitic connection feed arm, and the arm width of the main radiating arm refers to a width of the main radiating arm in a direction in which the length of the connection feed arm extends; A second frequency band helical antenna arm, comprising four groups of helical antenna arms, each group of helical antenna arms comprising a wide arm, a first open branch, a second open branch, and a third open branch, wherein the length of the first open branch is greater than the length of the second open branch, the length of the second open branch is greater than the length of the third open branch, and the first open branch, the second open branch, and the third open branch are connected to a feed arm; The length of each of the first frequency band helical antenna arm and the second frequency band helical antenna arm is an integral multiple of one quarter of the wavelength, and the amplitudes of the currents of the feeding sections of the first frequency band helical antenna arm and the second frequency band helical antenna arm are equal and the phases of the currents differ by 90 degrees respectively; The dual-band four-arm helical antenna also includes a dielectric support column, which is a hollow cylinder. The dielectric support column is fixed on a metal support plate, and the first-band helical antenna arm is evenly wound on the outside of the dielectric support column, and the second-band helical antenna arm is evenly wound on the inside of the dielectric support column. The first-band helical antenna arm and the second-band helical antenna arm have the same length in the extension direction of the axis of the dielectric support column.

2. The dual-frequency quadrifilar helical antenna according to claim 1, characterized in that It also includes a feeding network, which is a multi-stage RC-CR feeding network. The multi-stage RC-CR feeding network is cascaded by a single-stage RC-CR feeding network, and the single-stage RC-CR feeding network includes 4 resistors and 4 capacitors.

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