Patent Description:
The present disclosure relates to the field of satellite positioning technology, and in particular to a helical antenna.

The cited document D1 (<CIT>) discloses a helical antenna capable of covering multiple frequency bands and using commonly a feeder system for antenna elements adjusted to the respective frequency bands. First and second antenna elements adjusted in length to wavelengths of the frequency bands to be used are arranged helically at a specified pitch angle with a spacing between each other in the circumferential direction of a cylindrical body on the surface of a dielectric sheet wound around the outer circumferential surface of the cylindrical body. Coupling lines to be electromagnetically coupled to one-side ends of the antenna elements being adjacent to one another are formed on the surface of the dielectric sheet. Signal is fed from a common feeder circuit through the coupling lines to the respective antenna elements.

The cited document D2 (<CIT>) discloses a quadrifilar helical antenna for communicating in multiple different frequency bands. The quadrifilar helical antenna includes at least two ports. Each port is operationally coupled with a port-specific set of helical filars, the port-specific set of filars includes at least one band-specific filar for each of the multiple different frequency bands. At least two of the band-specific filars, the band-specific filars belonging to different band-specific filars and different port-specific sets adjacent to each other, have mutual coupling between the ports, the mutual coupling resulting in a destructive phasing of the frequency bands between the at least two of the band-specific filars.

The cited document D3 (<CIT>) discloses a bent-segment helical antenna utilizing one or more radiators wrapped in a helical fashion. The radiators are comprised of multiple segments. A first segment extends from a feed network at a first end of a radiator portion of the antenna toward a second end of the radiator portion. A second segment is adjacent to and offset from the first segment. A third segment connects the first and second segments at the second end of the radiator portion.

The cited document D4 (<CIT>) discloses a tightly integrated combined transmit and receive dual quadrifilar antenna. The antenna includes four helical transmit elements and four helical receive elements disposed about a common axis. A receiver front end includes an arrangement of two <NUM> degree hybrids which serve to effectively reject signals cross coupled from the transmit elements back into the receive elements, while still allowing the receiver to receive signals.

Generally, a microstrip ceramic or a microwave dielectric patch antenna based on a microstrip patch antenna principle is usually used in the global satellite positioning technology. Such antenna is made of ceramics as a dielectric material to form square or circle antenna patches with different thicknesses, then a reflection surface and a radiation surface are formed respectively on two sides of the antenna patch through a low temperature silver baking process, and next, a satellite navigation antenna is formed by feeding the antenna patch via a feed needle.

However, the satellite navigation antenna described above has many disadvantages. For example, an antenna made of ceramic material has a higher dielectric constant, which results in a narrow frequency bandwidth of the antenna. Moreover, a positioning antenna with such structure has a high requirement on dimensional accuracy of the radiation surface. The gain of the microstrip patch antenna is easily affected by the size and shape of the reflective ground plane, thus it is usually required to perform a manual adjustment on the satellite navigation antenna through a network analyzer, such that the center frequency of the satellite navigation antenna falls within a frequency range that meets the actual requirements. In addition, the ceramic material has a large specific gravity, and the microwave dielectric patch antenna also has a large size, which may result in a large weight of the satellite navigation antenna.

Moreover, in the field of unmanned aerial vehicle, it is the quadrifilar helix antenna proposed by Kilgus at Johns Hopkins University in America that are widely applied currently. The quadrifilar helix antenna is made of four wires each having a length of half a wavelength and each twined in half a circle spiral. In recent years, a double quadrifilar helix antenna including two sets of helix antennas each having a length of a quarter wavelength is also provided, and a tuning bar is added to the double quadrifilar helix antenna to perform frequency separation and matching.

However, the above quadrifilar helix antenna is a resonator antenna, which only has about <NUM>% narrow frequency band, and only can cover GPS/BDS or GPS/GLONASS but cannot completely cover the conventional mainstream global satellite navigation frequencies. For the double quadrifilar helix antenna, its frequency bandwidth is much narrower than that of the quadrifilar helix antenna, and the frequency bandwidth of the double quadrifilar helix antenna in GPS L1 is only about <NUM>, which cannot cover the mainstream satellite positioning system frequencies.

In order to solve the above problems, a helical antenna is provided in an embodiment of the present disclosure, which is capable to increase the frequency bandwidth.

The helical antenna according to an embodiment of the present disclosure includes a printed circuit board and a radiation body arranged on the printed circuit board, in which the radiation body includes at least one main helical arm and at least one parasitic helical arm, each main helical arm corresponds to at least one parasitic helical arm, each main helical arm is arranged in parallel with and is spaced with its corresponding parasitic helical arm, in which,.

In an embodiment, a side of the printed circuit board facing towards the radiation body is provided with a feed network, and a side of the printed circuit board away from the radiation body is provided with a signal processing circuit, in which,.

In an embodiment, the feed network includes a phase shifter and a balun, in which an input terminal of the phase shifter is electrically connected to each of feed output terminals, an output terminal of the phase shifter is electrically connected to an input terminal of the balun, and an output terminal of the balun is electrically connected to an input terminal of the signal processing circuit.

In an embodiment, the signal processing circuit includes a duplex filter, a low noise amplifier, a duplex combiner and a driver amplifier, in which,.

In an embodiment, the printed circuit board is provided with a through hole passing through the printed circuit board along a thickness direction of the printed circuit board, and the input terminal of the duplex filter is electrically connected to the output terminal of the feed network via the through hole.

In an embodiment, a helix angle of the main helical arm ranges from <NUM> degrees to <NUM> degrees.

In an embodiment, the helical antenna further includes a flexible printed circuit board, in which the flexible printed circuit board is rolled into a cylinder, a cone or a rectangular column, and the radiation body surrounds an outer peripheral surface of the flexible printed circuit board.

In an embodiment, the radiation body is formed on the outer peripheral surface of the flexible printed circuit board by a copper plating process or a low-temperature silver baking process.

In an embodiment, the radiation body is formed by a microstrip line with a wavelength of <NUM> twining around the outer peripheral surface of the flexible printed circuit board.

In an embodiment, a thickness of the printed circuit board ranges from <NUM> to <NUM>.

In an embodiment, the radiation body includes four main helical arms and four parasitic helical arms.

In an embodiment, each parasitic helical arm exceeds its corresponding main helical arm by <NUM> circle to <NUM> circle.

The helical antenna according to an embodiment of the present disclosure has a radiation body including at least one main helical arm and at least one parasitic helical arm, in which each main helical arm is arranged in parallel with and is spaced with its corresponding parasitic helical arm. The main helical arm may lead to a resonance occurring at a high frequency, and the parasitic helical arm may lead to a resonance occurring at a low frequency, such that the frequency bandwidth of the helical antenna is expanded to <NUM>%, thereby achieving an object of covering dual-frequency GPS/BDS/GLONASS satellite navigation frequency and L-Band frequency. In addition, a helix angle of a part of the parasitic helical arm exceeding its corresponding main helical arm is less than a helix angle of a part of the parasitic helical arm not exceeding its main helical arm, which can reduce a size of the helical antenna so as to make the structure of the helical antenna more compact, under a premise of ensuring necessary performance of the helical antenna.

Other features, objects and advantages of the present disclosure will become clearer by reading the following specific descriptions of nonrestrictive embodiments made with reference to the drawings.

The present disclosure is described in detail below in conjunction with the drawings and embodiments. It is understandable that specific embodiments described herein are used to simply explain the present disclosure, but not to limit the present disclosure. It also should be noted that for easy of description, the drawings merely show the related parts to the present disclosure.

It should be noted that embodiments of the present disclosure and features in the embodiments may be in combination with each other as long as there is no conflict. The helical antenna according to the embodiments of the present disclosure will be described in detail below with reference to the drawings and in conjunction with the embodiments.

As shown in <FIG> and <FIG>, a helical antenna <NUM> is provided in an embodiment of the present disclosure. The helical antenna <NUM> includes a printed circuit board <NUM> and a radiation body <NUM> arranged on the printed circuit board <NUM>. The radiation body <NUM> includes at least one main helical arm <NUM> and at least one parasitic helical arm <NUM>, in which each main helical arm <NUM> corresponds to at least one parasitic helical arm <NUM>, and each main helical arm <NUM> is arranged in parallel with and is spaced with its corresponding parasitic helical arm <NUM>.

A first terminal of each main helical arm <NUM> is electrically connected to a first terminal of its corresponding parasitic helical arm <NUM>, to form a feed output terminal OUT of the helical antenna <NUM>. A second terminal of each main helical arm <NUM> and a second terminal of the parasitic helical arm <NUM> are both in a floating state.

Here it should be noted that the floating state refers to that the second terminal of the main helical arm <NUM> and the second terminal of the parasitic helical arm <NUM> are both in an open circuit state.

In some embodiments, as shown in <FIG>, a length of the parasitic helical arm <NUM> is greater than a length of its corresponding main helical arm <NUM>. A helix angle β of a part of the parasitic helical arm <NUM> exceeding its corresponding main helical arm <NUM> is less than a helix angle α of a part of the parasitic helical arm <NUM> not exceeding its corresponding main helical arm <NUM>, which is capable to reduce a size of the helical antenna <NUM> so as to make a structure of the helical antenna <NUM> more compact, under a premise of ensuring necessary performance of the helical antenna <NUM>.

In a specific example, as shown in <FIG>, the radiation body <NUM> of the helical antenna <NUM> may include four main helical arms <NUM> and four parasitic helical arms <NUM>. In practice, other numbers of main helical arms <NUM> and parasitic helical arms <NUM> may also be selected according to actual requirements.

In a case that the radiation body <NUM> include four main helical arms <NUM> and four parasitic helical arms <NUM>, a first terminal (which is the terminal close to the printed circuit board <NUM> shown in <FIG>) of each of the four main helical arms <NUM> is electrically connected to a first terminal (which is the terminal close to the printed circuit board <NUM> shown in <FIG>) of its corresponding parasitic helical arm <NUM>. In a specific embodiment, the first terminal of the main helical arm <NUM> may be electrically connected to the first terminal of the parasitic helical arm <NUM> via a metal connection part. Alternatively, the first terminal of the main helical arm <NUM> may also be electrically connected to the first terminal of the parasitic helical arm <NUM> in other electrical connection manner. Second terminals of the four main helical arms <NUM> and second terminals of the four parasitic helical arms <NUM> are all in the open circuit state (that is, in the floating states). Moreover, as shown in <FIG>, a helix angle β of a top part of the parasitic helical arm <NUM> is less than a helix angle α of a bottom part of the parasitic helical arm <NUM>.

In an embodiment, as shown in <FIG>, a helix angle α of the above main helical arm <NUM> may range from <NUM> degrees to <NUM> degrees. Accordingly, a helix angle α of a part of the parasitic helical arm <NUM> not exceeding its corresponding main helical arm <NUM> may also range from <NUM> degrees to <NUM> degrees. A helix angle β of a part of the parasitic helical arm <NUM> exceeding its corresponding main helical arm <NUM> may range from <NUM> degrees to <NUM> degrees.

In an embodiment, as shown in <FIG> and <FIG>, the helical antenna <NUM> may further include a flexible printed circuit board <NUM>. The flexible printed circuit board <NUM> is rolled into a cylinder, a cone or a rectangular column, and the radiation body <NUM> surrounds an outer peripheral surface of the flexible printed circuit board <NUM>.

Specifically, the radiation body <NUM> may be formed on the outer peripheral surface of the flexible printed circuit board <NUM> by a copper plating process or a low-temperature silver baking process.

In addition, the radiation body <NUM> may be formed by a microstrip line of <NUM> wavelength twining around the outer peripheral surface of the flexible printed circuit board <NUM>.

Specifically, the flexible printed circuit board <NUM> may be a polytetrafluoroethylene board. In practice, a microstrip line may be arranged on the flexible printed circuit board <NUM> based on a specific helix angle and a length. Then the microstrip line is rolled into a helix line, to form the radiation body <NUM>.

In an embodiment, the main helical arm <NUM> of the radiation body <NUM> twines around the outer peripheral surface of the flexible printed circuit board <NUM> for <NUM> circle. The parasitic helical arm <NUM> of the radiation body <NUM> twines around the outer peripheral surface of the flexible printed circuit board <NUM> for <NUM> circles.

In an embodiment, as shown in <FIG> and <FIG>, each parasitic helical arm <NUM> may exceed its corresponding main helical arm <NUM> by <NUM> circle to <NUM> circle, preferably <NUM> circle.

The helical antenna <NUM> according to an embodiment of the present disclosure has a radiation body <NUM> including at least one main helical arm <NUM> and at least one parasitic helical arm <NUM>, in which each main helical arm <NUM> is arranged in parallel with and is spaced with its corresponding parasitic helical arm <NUM>. The main helical arm <NUM> may lead to a resonance occurring at a high frequency, and the parasitic helical arm <NUM> may lead to a resonance occurring at a low frequency, such that the frequency bandwidth of the helical antenna <NUM> is expanded to <NUM>%, thereby achieving an object of covering dual-frequency GPS/BDS/GLONASS satellite navigation frequency and L-Band frequency. In some embodiments, a helix angle of a part of the parasitic helical arm <NUM> exceeding its corresponding main helical arm <NUM> is less than a helix angle of a part of the parasitic helical arm <NUM> not exceeding its main helical arm <NUM>, which can reduce a size of the helical antenna <NUM> so as to make the structure of the helical antenna <NUM> more compact, under a premise of ensuring necessary performance of the helical antenna <NUM>.

In some implementations of the embodiment of the present disclosure, as shown in <FIG> and <FIG>, a side of the printed circuit board <NUM> facing towards the radiation body <NUM> is provided with a feed network <NUM>. Moreover, the side (that is the side facing towards the radiation body <NUM>) of the printed circuit board <NUM> may be a ground plane, to form a reflection surface of the helical antenna <NUM>. The printed circuit board <NUM> may be a FR-<NUM> multilayer board, and a thickness of the printed circuit board <NUM> may range from <NUM> to <NUM>. A side of the printed circuit board <NUM> away from the radiation body <NUM> is provided with a signal processing circuit. An input terminal of the feed network <NUM> is electrically connected to each feed output terminal OUT, and an output terminal of the feed network <NUM> is electrically connected to an input terminal of the signal processing circuit. The feed network <NUM> is configured to synthesize signals outputted from the feed output terminals OUT, to obtain a circularly polarized signal.

Specifically, as shown in <FIG> and <FIG>, the feed network <NUM> may include two phase shifters 111a (the phase shifter 111a may be a <NUM> degree phase shifter) and one balun 111b (the balun 111b may be a <NUM> degree balun). In a case that the radiation body <NUM> includes four main helical arms <NUM> and four parasitic helical arms <NUM>, an input terminal of one of the two phase shifters 111a may be electrically connected to two feed output terminals OUT1 and OUT2, and an input terminal of the other phase shifter 111a may be electrically connected to the other two feed output terminals OUT3 and OUT4. Moreover, output terminals of the two phase shifters 111a are electrically connected to an input terminal of the balun 111b, and an output terminal of the balun 111b is electrically connected to an input terminal of the signal processing circuit.

Specifically, in an example, as shown in <FIG>, the signal processing circuit may include a duplex filter <NUM>, a low noise amplifier <NUM>, a duplex combiner <NUM> and a driver amplifier <NUM>. An input terminal of the duplex filter <NUM> is electrically connected to the output terminal of the balun 111b, and an output terminal of the duplex filter <NUM> is electrically connected to an input terminal of the low noise amplifier <NUM>. An input terminal of the duplex combiner <NUM> is electrically connected (directly or via a filter <NUM>) to an output terminal of the low noise amplifier <NUM>, and an output terminal of the duplex combiner <NUM> is electrically connected to an input terminal of the driver amplifier <NUM>. An output terminal of the driver amplifier <NUM> is configured to be electrically connected to a satellite positioning receiver <NUM>.

In practice, in order to realize electrical connection between the feed network <NUM> and the signal processing circuit on the printed circuit board <NUM>, the printed circuit board <NUM> may be provided with a through hole (not shown) passing through the printed circuit board <NUM> along a thickness direction of the printed circuit board <NUM>. In this way, the input terminal of the duplex filter <NUM> can be electrically connected to the output terminal of the feed network <NUM> via the through hole.

A specific signal transmission process of the helical antenna <NUM> is described below, in which the helical antenna <NUM> includes four main helical arms <NUM> and four parasitic helical arms <NUM> is taken as an example.

Specifically, as shown in <FIG>, <FIG> and <FIG>, the four main helical arms <NUM> and the four parasitic helical arms <NUM> form four feed output terminals OUT1, OUT2, OUT3 and OUT4. The four feed output terminals OUT1, OUT2, OUT3 and OUT4 are welded to the printed circuit board <NUM>, so as to transmit signals to the feed network <NUM> on the printed circuit board <NUM> in a coupling manner. The feed network <NUM> synthesizes orthogonal signals to obtain a circularly polarized signal, and the circularly polarized signal is transmitted to the signal processing circuit at bottom via the through hole of the printed circuit board <NUM>. Then the duplex filter <NUM> filters out a high frequency signal and a low frequency signal. The low noise amplifier <NUM> amplifies satellite navigation signals received in the two frequency bands. Then secondary filtering is performed on the amplified signals by the filter <NUM>, and the filtered signals are synthesized by the duplex combiner <NUM>. Then the synthesized signal is amplified by the driver amplifier <NUM>, to obtain a target signal that meets requirements. Then the target signal is transmitted to the satellite positioning receiver <NUM> through a cable.

As shown in <FIG>, the helical antenna <NUM> according to the embodiment of the present disclosure has a maximum gain exceeding 3dBi at the dual-frequency GPS/BDS/GLONASS satellite navigation frequency and L-Band, and has a gain of -<NUM>. 2dBi at <NUM> degree low elevation. As shown in <FIG>, a reflection of the feed output terminal is greater than 9dB, which meets demands for a helical antenna. As shown in <FIG>, a polarization axial ratio of the helical antenna is <NUM> dB and a low elevation is less than 2dB, which reaches conventional technical levels. In addition, the helical antenna <NUM> according to the present disclosure can further effectively reduce a size of the helical antenna <NUM>, so as to make a structure of the helical antenna <NUM> more compact.

Claim 1:
A helical antenna system, comprising a printed circuit board (<NUM>) and a radiation body (<NUM>) arranged on the printed circuit board (<NUM>), wherein the radiation body (<NUM>) comprises at least one main helical arm (<NUM>) and at least one parasitic helical arm (<NUM>), each main helical arm (<NUM>) corresponds to at least one parasitic helical arm (<NUM>), each main helical arm (<NUM>) is arranged in parallel with and is spaced with its corresponding parasitic helical arm (<NUM>), wherein,
a first terminal of each main helical arm (<NUM>) is electrically connected to a first terminal of the corresponding parasitic helical arm (<NUM>), to form a feed output terminal of the helical antenna system;
a second terminal of the main helical arm (<NUM>) and a second terminal of the parasitic helical arm (<NUM>) are both in a floating state; and
a length of the parasitic helical arm (<NUM>) is greater than a length of its corresponding main helical arm (<NUM>), and characterized in that: a helix angle (β) of a part of the parasitic helical arm (<NUM>) exceeding its corresponding main helical arm (<NUM>) is less than a helix angle (α) of a part of the parasitic helical arm (<NUM>) not exceeding its corresponding main helical arm (<NUM>).