A shortwave high-gain variable-element Yagi antenna and its adjustment method

Abstract

The present invention proposes a shortwave high-gain variable-divider multi-element Yagi antenna and an adjustment method thereof. The present invention comprises a truss, a rotating mechanism, a plurality of fixed dividers, a plurality of variable dividers and a divider adjustment device thereof; all dividers are fixed on the truss at set intervals, and the rotating mechanism is used to drive the truss to rotate to achieve shortwave communications in different directions; the divider adjustment device is configured in a one-to-one correspondence with the variable divider, and is used to adjust the length of the corresponding variable divider to achieve working frequency tuning. The present invention reasonably arranges the number, position and length of the guiding dividers and the reflecting dividers, and at the same time introduces the adjustment of the length of the reflecting dividers, the active dividers and some of the guiding dividers, so as to achieve the characteristics of a 10dBi-15dBi high-gain radiation pattern in the full frequency band of shortwave 7-30MHz.

Description

Technical Field

[0001] The invention belongs to the technical field of antenna communication, and in particular relates to a short-wave high-gain variable-dividing-element Yagi antenna. Background Art

[0002] Shortwave communication still plays an irreplaceable and important role in modern military communication, and shortwave antenna, as an important component of shortwave communication equipment, is equally important. For a long time, people have been striving to pursue the goals of wideband, high gain, and miniaturization in shortwave communication. However, due to the generally large size of antennas in this frequency band, it is difficult to achieve the above goals. At present, there are no related technical reports except for shortwave log-periodic array antennas.

[0003] Patent document CN109861006 A discloses a multi-drive unit generalized Yagi antenna and an optimization method thereof. The number of drive units, reflectors and directors of the Yagi antenna described in the patent document is not limited and needs to be adjusted and determined according to on-site requirements. At the same time, the lengths of the drive units, reflectors and director units in the patent document are fixed, so their operating frequencies are also fixed.

[0004] Patent document CN106450774 A discloses an ultra-wideband high-gain Yagi antenna, in which the excitation unit of the Yagi antenna adopts a broadband folded dipole form with dual feed points, achieving high gain and 1.7-2.24GHz wideband characteristics. However, the lengths of the excitation unit, the guide unit and the reflector are all fixed.

[0005] Patent document CN205944387 U discloses an adjustable Yagi antenna, which includes an active oscillator, a passive reflector and a plurality of passive directors. A connecting slider is slidably connected to two supporting screw rods to achieve rapid adjustment of the spacing between each unit, but the length of each unit oscillator is fixed.

[0006] It can be seen that the length of each unit antenna of various existing Yagi antennas is fixed, so when the frequency changes within the shortwave 7-30MHz frequency band, it is impossible to achieve high-gain communication requirements within the entire frequency band.

[0007] On the other hand, traditionally a 2×2 logarithmic periodic array is required to achieve the above-mentioned high gain index. This type of antenna array occupies a large area and is very complex to install. Summary of the invention

[0008] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and propose a shortwave high-gain variable-element Yagi antenna that can achieve the characteristics of a 10dBi-15dBi high-gain radiation pattern in the full frequency band of shortwave 7-30MHz.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A shortwave high-gain variable-divider multi-element Yagi antenna is special in that it comprises a truss, a rotating mechanism, a plurality of fixed dividers, a plurality of variable dividers and a divider adjusting device thereof; the plurality of variable dividers are divided into a reflecting divider, an active divider and a plurality of variable guiding dividers according to their functional attributes; the longest one of the plurality of fixed dividers is located between the reflecting divider and the active divider, and the remaining fixed dividers are all used as fixed guiding dividers; all the dividers are fixed on the truss at set intervals, and the rotating mechanism is used to drive the truss to rotate so as to realize shortwave communication in different directions; the divider adjusting device is configured in a one-to-one correspondence with the variable dividers and is used to adjust the length of the corresponding variable divider so as to realize working frequency tuning.

[0011] Furthermore, the metal strip used for the variable vibrator is evenly provided with a plurality of positioning holes along its length direction, and the vibrator adjustment device includes a motor and its servo mechanism, and the servo mechanism adopts a form of a transmission gear disk that cooperates with the positioning holes to engage and roll, so as to achieve adjustment of the effective length of the variable vibrator.

[0012] Furthermore, the vibrator adjustment device includes a motor, a reducer, a transmission tooth assembly, a vibrator recovery disk and a vibrator guide, and the variable vibrator is divided into a first straight section, a first transmission tooth matching section, a recovery section, a second transmission tooth matching section and a second straight section in sequence, and the first straight section and the second straight section are respectively transitioned into a first transmission tooth matching section and a second transmission tooth matching section according to the deflection of the vibrator guide, and the first transmission tooth matching section and the second transmission tooth matching section are at different height positions but are located in the same vertical plane; the input shaft of the reducer is connected to the output shaft of the motor, and the transmission tooth assembly is arranged on the output shaft of the reducer, and the transmission tooth assembly includes two coaxial transmission tooth discs, and the two transmission tooth discs are connected by an insulating column; the two transmission tooth discs are respectively adapted to be clamped with the positioning holes on the first transmission tooth matching section and the second transmission tooth matching section; the recovery section is wrapped around the vibrator recovery disk.

[0013] Furthermore, the shortwave high-gain variable-element Yagi antenna also includes a plurality of variable-element support rods, each variable element is built into a corresponding variable-element support rod, and the variable element can be freely extended and retracted in the variable-element support rod.

[0014] Furthermore, all vibrators (fixed vibrators and variable vibrators) are parallel to each other and are arranged perpendicular to the truss.

[0015] Furthermore, the rotating mechanism includes a driving motor, a rotating disk and a fixed bracket, the driving motor and the rotating disk are both mounted on the fixed bracket, the truss is mounted on the rotating disk, and the driving motor is used to drive the rotating disk and then drive the truss to rotate. Here, the driving motor can also be composed of a motor and a reducer.

[0016] Furthermore, there are a total of 7 variable vibrators, among which the longest one is used as a reflection vibrator, the second longest one is an active vibrator, and the remaining five are variable guiding vibrators; there are a total of 7 fixed vibrators, which are composed of metal rods of four different lengths, among which the longest fixed vibrator is located between the reflection vibrator and the active vibrator, and the remaining fixed vibrators are used as fixed guiding vibrators.

[0017] Furthermore, the active vibrator is a flat and long ring vibrator with an opening in the middle, and the requirement of a resonant operating frequency of 4-7 MHz is achieved by adjusting the length of the bent vibrator.

[0018] The present invention also provides a shortwave medium-gain bidirectional radiation variable vibrator antenna, which is special in that it includes a truss, a rotating mechanism, a plurality of variable vibrators and a vibrator adjustment device; the plurality of variable vibrators are fixed on the truss at set intervals, and the rotating mechanism is used to drive the truss to rotate to achieve shortwave communication in different directions; the vibrator adjustment device is configured in a one-to-one correspondence with the variable vibrator, and is used to adjust the length of the corresponding variable vibrator to achieve working frequency tuning.

[0019] The shortwave medium-gain bidirectional radiation variable dipole antenna can be optimized by referring to the further optimization scheme of the above-mentioned shortwave high-gain variable dipole multi-element Yagi antenna.

[0020] The above-mentioned method for adjusting the shortwave high-gain variable-element Yagi antenna is special in that it includes:

[0021] 1) Adjustment of the length of the active oscillator

[0022] The standing wave ratio of the antenna is measured through the impedance test module;

[0023] The length of the active vibrator is continuously adjusted until the current standing wave ratio is ≤2:1, at which point the length of the active vibrator is the optimal length;

[0024] 2) Adjustment of the length of the passive oscillator

[0025] According to theoretical calculation, the length of the passive vibrator is adjusted to the theoretical value;

[0026] The UAV antenna test system is used to measure the antenna gain;

[0027] The length of each passive oscillator is continuously adjusted to find the maximum value of the gain. At this time, the length of the passive oscillator is the optimal length.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) The variable vibrator of the present invention is adjustable in length and the overall direction of the antenna is adjustable. By rationally arranging the number, position and length of the guiding vibrator and the reflecting vibrator, and introducing the adjustment of the length of the reflecting vibrator, the active vibrator and some of the guiding vibrators, the characteristics of a 10dBi-15dBi high-gain radiation pattern in the full shortwave 7-30MHz frequency band can be achieved.

[0030] (2) The present invention can achieve the same gain pattern characteristics while occupying only half the floor space of a log-periodic array antenna, reducing the installation height by half, and is relatively easy to install.

[0031] (3) The present invention has a rotatable mechanism, so the radiation direction of the antenna can be adjusted arbitrarily, which is impossible for a traditional log-periodic array with the same gain.

[0032] (4) Since the present invention occupies a small area and does not require array arrangement, the number of antenna units is small, thus greatly reducing the cost of the antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the overall structure of a shortwave high-gain variable-element Yagi antenna according to an embodiment;

[0034] Figure 2 for Figure 1 A schematic diagram of the structure of the active vibrator feeding component;

[0035] Figure 3 for Figure 1 Transmission diagram of the variable oscillator.

[0036] Figure 4 for Figure 1 Schematic diagram of the vibrator extension of the variable vibrator transmission mechanism.

[0037] Figure 5 for Figure 1 Schematic diagram of the variable vibrator transmission mechanism with the vibrator folding.

[0038] Figure 6 for Figure 1 The oscillator arrangement diagram.

[0039] Figure 7 for Figure 5 Schematic diagram of the variable vibrator shape support structure.

[0040] Figure 8 for Figure 5 Schematic diagram of the truss element in .

[0041] Fig. 9 for Figure 5 Schematic diagram of the fixed oscillator in .

[0042] Fig.10 for Figure 1 Schematic diagram of the rotation structure in .

[0043] Fig.11 This is a schematic diagram of an extended 4-30MHz shortwave high-gain variable-element multi-element Yagi antenna.

[0044] Fig.12 This is a simplified schematic diagram of a shortwave medium-gain bidirectional radiation variable dipole antenna.

[0045] Description of Figure Numbers:

[0046] 1 - truss; 2 - rotating mechanism; 3 - fixed vibrator; 4 - variable vibrator; 5 - variable vibrator shape support rod; 6 - vibrator adjustment device; 7 - control unit;

[0047] 2-1——top rotating disk; 2-2——motor + speed reducer; 2-3 rotating disk body; 2-4-slewing bearing; 2-5——direction finding encoder;

[0048] 3-1 is the longest fixed vibrator, 3-2, 3-3, 3-4, 3-5, 3-6, and 3-7 are the fixed vibrators that guide the vibrators;

[0049] 3-1-1——Fix the small vibrator tube; 3-1-2——Fix the large vibrator tube; 3-1-3——Clamp the vibrator base; 3-1-4——Fix the vibrator base;

[0050] 4-1 - a variable vibrator as a reflector vibrator; 4-2 - a variable vibrator as an active vibrator; 4-3, 4-4, 4-5, 4-6, 4-7 - variable vibrators as guide vibrators;

[0051] 5-1——sealing cap; 5-2, 5-4, 5-6, 5-8, 5-10——oscillator tube; 5-3, 5-5, 5-7, 5-9——oscillator joint;

[0052] 6-1——variable vibrator radiator (first straight line segment); 6-2——vibrator driver; 6-3——control plug; 6-4——vibrator recovery disk; 6-5——winding magnetic disk; 6-6——vibrator feeding device; 6-7——vibrator transmission device (transmission gear disk); 6-8——vibrator guide; 6-9——driving motor; 6-10——drive shaft connected to insulating column. DETAILED DESCRIPTION

[0053] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0054] Example 1, 7-30MHz shortwave high gain variable oscillator multi-element Yagi antenna:

[0055] Reference Figure 1 The shortwave high-gain variable-element Yagi antenna of the present invention comprises a truss 1, a rotating mechanism 2, seven fixed elements 3, seven variable elements 4, a variable element outer shape support rod 5, an element adjustment device 6 and a control unit.

[0056] Rotating mechanism 2 can rotate 360 ​​degrees 0 Rotate to achieve shortwave communication in different directions. The fixed vibrators 3 and variable vibrators 4 are 14 in total, which together form a multi-element Yagi antenna, including 7 fixed vibrators 3 and 7 variable vibrators 4, and all vibrators are fixed on the truss 1 at a certain interval. The variable vibrator 4 is built into the variable vibrator shape support rod 5, and the control unit 7 changes the length of the vibrator through the vibrator adjustment device 6 to achieve the purpose of working frequency tuning; under different working frequency states, with the change of the length of the variable vibrator 4 and the increase or decrease of the effect of the fixed vibrator 3, the number of vibrators of the Yagi antenna that actually works is also changing, achieving high-gain directional pattern characteristics at different frequency points.

[0057] The truss 1 is composed of three truss units spliced ​​together according to the required length. Each truss unit is assembled into a triangular prism structure by three metal angle aluminums. The structure is stable and reliable, and each truss unit is 4.5 meters long.

[0058] The rotating mechanism 2 includes four parts: a motor, a reducer, a rotating disk, and a fixed bracket. The motor, the reducer, and the rotating disk are all installed on the fixed bracket, and the fixed bracket is installed on the truss 1.

[0059] The vibrator adjustment device 6 includes 7 small motors and their servo mechanisms 6 - 1 , 6 - 2 , 6 - 3 , 6 - 4 , 6 - 5 , 6 - 6 , and 6 - 7 , which are respectively installed in the middle of the variable vibrator 4 .

[0060] There are 7 variable vibrators 4, including 5 long ones and 2 short ones; the longest one is the reflection vibrator 4-1, with the longest length of 2100cm; the second longest is the active vibrator 4-2, with the longest length of 2050cm; the other three longer ones are the guiding vibrators 4-3, 4-4, and 4-5, with the longest length of 2000cm respectively; the two short ones are also the guiding vibrators 4-6 and 4-7, with the longest length of 1000cm.

[0061] There are 7 fixed vibrators 3, which are made of carbon fiber tubes and are divided into four different lengths. The longest fixed vibrator 3-1 is 1500cm long and is located between the reflective vibrator 4-1 and the active vibrator 4-2, 300cm away from the active vibrator 4-1. The remaining fixed vibrators 3-2, 3-3, 3-4, 3-5, 3-6, and 3-7 are all used as guide vibrators, with lengths of 673cm, 637cm, 612cm, 612cm, 624cm, and 637cm respectively. The distance between the variable vibrator 4-1 and the fixed vibrator 3-1 is 5 meters, the distance between the fixed vibrator 3-1 and the fixed vibrator 3-2 is 2.5 meters, and the distance between the fixed vibrator 3-2 and the variable vibrator 4- 2 The spacing is 2.5 meters, the spacing between variable vibrator 4-2 and fixed vibrator 3-3 is 2.5 meters, the spacing between fixed vibrator 3-3 and variable vibrator 4-3 is 2.5 meters, the spacing between variable vibrator 4-3 and fixed vibrator 3-4 is 2.5 meters, the spacing between fixed vibrator 3-4 and variable vibrator 4-4 is 2.5 meters, the spacing between variable vibrator 4-4 and fixed vibrator 3-5 is 2.5 meters, the spacing between fixed vibrator 3-5 and variable vibrator 4-5 is 2.5 meters, the spacing between variable vibrator 4-5 and fixed vibrator 3-6 is 2.5 meters, the spacing between fixed vibrator 3-6 and variable vibrator 4-6 is 2.5 meters, the spacing between variable vibrator 4-6 and fixed vibrator 3-7 is 3 meters, and the spacing between fixed vibrator 3-7 and variable vibrator 4-7 is 4.5 meters.

[0062] The fixed vibrator 3 and the variable vibrator 4 are both fixed on the truss 1. Figure 6 .

[0063] The length of the active vibrator 4-2 can be changed by the vibrator adjustment device 6-2 to achieve tuning of different operating frequencies.

[0064] The lengths of the variable oscillators 4-1, 4-3, 4-4, 4-5, 4-6, and 4-7 can be changed by oscillator adjustment devices 6-1, 6-3, 6-4, 6-5, 6-6, and 6-7, respectively, to achieve a high-gain radiation pattern.

[0065] The variable vibrator shape support rod 5 is formed by sleeve-joining non-metallic tubes (glass fiber reinforced plastic tubes) of different diameters and is fixed on the truss 1 .

[0066] The variable vibrator 4 is made of a uniformly perforated metal strip (metal strip line). When the vibrator adjustment device 6 adjusts the antenna length, the gear will be stuck in the hole of the steel belt to achieve transmission. The specific structure can be: the vibrator adjustment device includes a motor, a reducer, a transmission gear assembly, a vibrator recovery disk and a vibrator guide. The variable vibrator can be regarded as being divided into a first straight segment, a first transmission tooth matching segment, a recovery segment, a second transmission tooth matching segment and a second straight segment in sequence, wherein the first straight segment and the second straight segment are respectively transitioned into the first transmission tooth matching segment and the second transmission tooth matching segment according to the deflection of the vibrator guide, and the first transmission tooth matching segment and the second transmission tooth matching segment are at different height positions but are located in the same vertical plane; the input shaft of the reducer is connected to the output shaft of the motor, and the output of the reducer drives the transmission gear assembly, and the transmission gear assembly includes two coaxial transmission tooth discs, and the two transmission tooth discs are connected by an insulating column; the two transmission tooth discs are respectively adapted and clamped with the positioning holes on the first transmission tooth matching segment and the second transmission tooth matching segment; the recovery segment is wound around the vibrator recovery disk.

[0067] The control unit 7 is composed of a hardware circuit and control software to adjust the length of the variable antenna element 4 .

[0068] The method for adjusting the length of the active vibrator 4-2 is to measure the standing wave ratio of the antenna through the impedance test module in the hardware circuit. When the standing wave ratio is ≤2:1, the length of the active vibrator 4-2 is the optimal length.

[0069] The length adjustment method of the passive vibrators 4-1, 4-3, 4-4, 4-5, 4-6, and 4-7 is to use the control software to first adjust the length of the passive vibrators to the theoretical value, that is, the reflection vibrator 4-1 is about 0.5 wavelengths, and the guiding vibrators 4-3 to 4-7 are 0.43 wavelengths. Then, the gain of the antenna is measured using the UAV antenna test system. By continuously adjusting the length of each passive vibrator 4-1, 4-3, 4-4, 4-5, 4-6, and 4-7, the maximum gain is found. At this time, the lengths of the passive vibrators 4-1, 4-3, 4-4, 4-5, 4-6, and 4-7 are the optimal lengths.

[0070] The active oscillator 4-2 is fed with a 1:1 transmission transformer balanced feeding method.

[0071] When the Yagi antenna works in the 7-13MHz frequency band, the 5-element Yagi antenna composed of 4-1, 4-2, 4-4, 4-6, and 4-7 oscillators can achieve a gain of 10dBi.

[0072] When the Yagi antenna works in the 13-18MHz frequency band, the 6-element Yagi antenna is composed of 4-1, 4-2, 4-3, 4-4, 4-5, and 4-6 oscillators, and the gain can reach 12dBi.

[0073] When the Yagi antenna works in the 18-30MHz frequency band, the remaining oscillators except 4-1 and 4-7 form a 12-element Yagi antenna, and the gain can reach more than 14dBi.

[0074] This embodiment achieves the characteristics of a 10dBi-15dBi high-gain radiation pattern in the full shortwave 7-30MHz frequency band by reasonably arranging the number, position and length of the guiding oscillators and the reflecting oscillators, while introducing adjustments to the lengths of the reflecting oscillators, active oscillators and some of the guiding oscillators.

[0075] Example 2, extended 4-30MHz shortwave high-gain variable-element Yagi antenna:

[0076] Reference Fig.11 This embodiment is basically the same as the first embodiment, except that the length and form of the active vibrator 4-2 are different in order to extend the frequency point to 4 MHz. Since the operating frequency is lower, the length of the low-frequency vibrator needs to be longer. In order to reduce the lateral size of the antenna, the active vibrator 4-2 is changed to a flat long ring vibrator with an opening in the middle, and the 4-7 MHz resonant operating frequency requirement is achieved by adjusting the length of the curved vibrator.

[0077] Embodiment 3, a simplified shortwave medium-gain bidirectional radiation variable dipole antenna:

[0078] Reference Fig.12 The simplified shortwave medium-gain bidirectional radiation variable dipole antenna of the present invention comprises a truss 1, a rotating mechanism 2, variable dipoles 4-1, 4-2, 4-3, a variable dipole shape support rod 5, a dipole adjustment device 6 and a control unit 7. The variable dipoles 4-1 and 4-3 are passive dipoles, and the variable dipole 4-2 is an active dipole.

[0079] In order to reduce the lateral size of the antenna, the active vibrator 4-2 is changed into a flat long ring vibrator with an opening in the middle, and the resonant working frequency requirement is achieved by adjusting the length of the curved vibrator. When the length of the variable vibrator 4-1 is greater than the length of the active vibrator 4-2, the antenna radiates forward, and vice versa, when the length of the variable vibrator 4-3 is less than the length of the active vibrator 4-2, the antenna radiates backward.

[0080] The above description is only a specific example of the present invention. Obviously, for professionals in this field, after understanding the content and principles of the present invention, it is possible to make various modifications and changes in form and details without departing from the principles and structures of the present invention. However, these modifications and changes based on the ideas of the present invention are still within the scope of protection of the claims of the present invention.

Claims

1. A shortwave high-gain variable-element Yagi antenna, characterized in that: The invention comprises a truss (1), a rotating mechanism (2), a plurality of fixed vibrators (3), a plurality of variable vibrators (4) and a vibrator adjusting device (6); the plurality of variable vibrators (4) are divided into a reflecting vibrator, an active vibrator and a plurality of variable guiding vibrators according to their functional properties; the longest one of the plurality of fixed vibrators (3) is located between the reflecting vibrator and the active vibrator, and the remaining fixed vibrators are all fixed guiding vibrators; all vibrators are fixed on the truss (1) at a set interval; the rotating mechanism (2) is used to drive the truss (1) to rotate so as to realize shortwave communication in different directions; the vibrator adjusting device (6) is configured in a one-to-one correspondence with the variable vibrators (4) and is used to adjust the length of the corresponding variable vibrator so as to realize working frequency tuning; The variable vibrator (4) is provided with a plurality of positioning holes evenly arranged along its length direction on the metal strip line, and the vibrator adjustment device (6) comprises a motor and a servo mechanism thereof, wherein the servo mechanism adopts a form of a transmission gear disk that cooperates with the positioning holes to engage and roll, thereby realizing adjustment of the effective length of the variable vibrator (4); There are seven variable vibrators (4), of which the longest one is used as a reflection vibrator, the second longest one is an active vibrator, and the remaining five are variable guiding vibrators; there are seven fixed vibrators (3), which are composed of metal rods of four different lengths, of which the longest fixed vibrator (3-1) is located between the reflection vibrator and the active vibrator, and the remaining fixed vibrators are used as fixed guiding vibrators.

2. A shortwave high-gain variable-element Yagi antenna according to claim 1, characterized in that: The vibrator adjustment device (6) comprises a motor, a reducer, a transmission gear assembly, a vibrator recovery disk and a vibrator guide, the variable vibrator (4) is divided into a first straight section, a first transmission gear matching section, a recovery section, a second transmission gear matching section and a second straight section in sequence, the first straight section and the second straight section are respectively transitioned into a first transmission gear matching section and a second transmission gear matching section according to the deflection of the vibrator guide, and the first transmission gear matching section and the second transmission gear matching section are at different height positions but are located in the same vertical plane; the input shaft of the reducer is connected to the output shaft of the motor, the output shaft of the reducer is provided with the transmission gear assembly, the transmission gear assembly comprises two coaxial transmission gear discs, and the two transmission gear discs are connected by an insulating column; the two transmission gear discs are respectively adapted to be clamped with the positioning holes on the first transmission gear matching section and the second transmission gear matching section; the recovery section is wound around the vibrator recovery disk.

3. A shortwave high-gain variable-element Yagi antenna according to claim 1, characterized in that: It also comprises a plurality of variable vibrator shape support rods (5), each variable vibrator (4) is built into a corresponding variable vibrator shape support rod (5), and the variable vibrator (4) can freely expand and contract within the variable vibrator shape support rod (5).

4. A shortwave high-gain variable-element Yagi antenna according to claim 3, characterized in that: All the vibrators are parallel to each other and are arranged perpendicularly to the truss (1).

5. A shortwave high-gain variable-element Yagi antenna according to claim 1, characterized in that: The rotating mechanism (2) comprises a driving motor, a rotating disk and a fixed bracket, wherein the driving motor and the rotating disk are both mounted on the fixed bracket, and the truss (1) is mounted on the rotating disk. The driving motor is used to drive the rotating disk and thereby drive the truss (1) to rotate.

6. A shortwave high-gain variable-element Yagi antenna according to claim 1, characterized in that: The active vibrator is a flat and long ring vibrator with an opening in the middle, and the requirement of a resonant operating frequency of 4-7 MHz is achieved by adjusting the length of the bent vibrator.

7. A shortwave medium-gain bidirectional radiation variable dipole antenna, characterized in that: The invention comprises a truss (1), a rotating mechanism (2), a plurality of variable vibrators (4) and a vibrator adjusting device (6); the plurality of variable vibrators (4) are fixed on the truss (1) at set intervals, the rotating mechanism (2) is used to drive the truss (1) to rotate, so as to realize shortwave communication in different directions; the vibrator adjusting device (6) is configured in a one-to-one correspondence with the variable vibrators (4), and is used to adjust the length of the corresponding variable vibrators, so as to realize working frequency tuning; The variable vibrator (4) is provided with a plurality of positioning holes evenly arranged along its length on the metal strip line. The vibrator adjustment device (6) comprises a motor and a servo mechanism thereof. The servo mechanism adopts a form of a transmission gear disc that cooperates with the positioning holes to engage and roll, thereby achieving adjustment of the effective length of the variable vibrator (4).

8. The method for adjusting the shortwave high-gain variable-element Yagi antenna according to claim 1, characterized in that: include: 1) The length of the active vibrator is adjusted by measuring the standing wave ratio of the antenna through the impedance test module; the length of the active vibrator is continuously adjusted until the current standing wave ratio is ≤2:1, at which point the length of the active vibrator is the optimal length; 2) The length of the passive vibrator is adjusted to the theoretical value based on theoretical calculations; the gain of the antenna is measured using the drone antenna test system; the length of each passive vibrator is continuously adjusted to find the maximum value of the gain, at which point the length of the passive vibrator is the optimal length.

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