A coaxial series-parallel fed omnidirectional biconical dipole sleeve antenna

Abstract

The present invention relates to a coaxial serial-parallel fed omnidirectional biconical dipole sleeve antenna, which belongs to the field of antenna microwave technology and is composed of a biconical dipole sleeve antenna unit and a coaxial serial-parallel feeding network, mainly including a biconical dipole, a metal sleeve and a coaxial serial-parallel feeding network. The radiator gradient structure of the biconical dipole antenna unit can achieve better impedance matching with free space; the coaxial metal sleeve outside the radiator can further broaden the working bandwidth of the antenna unit; the biconical dipole antenna unit radiates omnidirectionally in the horizontal direction, and a coaxial serial-parallel feeding network is used to form an array in the vertical direction to achieve high gain performance of the antenna. The coaxial serial-parallel feeding network is composed of a linear gradient impedance transformation section and a two-stage coaxial power divider. The coaxial serial-parallel feeding network has no effect on the vertical plane directional pattern of the antenna, has a simple structure, is easy to implement, and can serve as a structural support for an omnidirectional antenna.

Description

Technical Field

[0001] The present invention belongs to the field of communication and radar technology and is related to the direction of antenna microwave technology. Background Art

[0002] Omnidirectional antennas are widely used in mobile communications, passive reconnaissance, electronic countermeasures and other fields due to their 360° coverage in the horizontal plane. Different application fields have different requirements for the working bandwidth, gain, polarization mode, structural form, etc. of omnidirectional antennas. At present, conventional omnidirectional antennas are mainly divided into two categories: one is to improve the monopole antenna, such as a single antenna such as a biconical antenna and a disc-conical antenna, and the polarization form is mostly vertical polarization; the other is to achieve horizontal or dual polarization in the form of an array composed of dipole antenna units. In order to achieve high gain, omnidirectional antennas generally have two implementation forms. One is to form an array of omnidirectional antenna units in the vertical direction, and the other is to use high-gain antenna units to form an array in the azimuth plane to achieve an omnidirectional radiation pattern and obtain high gain. Antenna units are generally fed by series feeding or parallel feeding, each of which has its own advantages and disadvantages: In theory, parallel feeding of array elements can ensure the consistency of amplitude and phase reaching each unit, but the structure of the feeding part is complex, which can easily affect the omnidirectional performance of the antenna in the horizontal plane; the structure of series feeding is simple and easy to implement, and the phase difference of each unit in the array will change with frequency, causing the vertical plane pattern of the omnidirectional antenna to scan, resulting in a narrowing of the working frequency band that meets the gain requirements.

[0003] In order to meet the requirements of broadband and high gain of omnidirectional antennas, the present invention designs a simple and efficient coaxial series-parallel feeding network to feed the double-conical dipole sleeve antenna arrayed in the vertical direction, which has a good impedance matching effect and realizes the high gain characteristics of the omnidirectional antenna. Summary of the invention

[0004] The present invention designs a coaxial series-parallel fed omnidirectional biconical dipole sleeve antenna, which adopts a coaxial series-parallel feeding network. While having a good impedance matching effect, it overcomes the influence of the feeding network on the omnidirectionality of the antenna and achieves the high gain performance of the omnidirectional antenna. The feeding network has a simple structure and is easy to implement.

[0005] The present invention is achieved through the following technical solutions:

[0006] The designed coaxial serial-parallel fed omnidirectional biconical dipole sleeve antenna is mainly composed of a sleeve biconical dipole antenna unit and a coaxial serial-parallel feeding network. Multiple biconical dipole antenna units are arrayed in the vertical direction to achieve the high gain characteristics of the antenna. From top to bottom, there are biconical dipole upper oscillator 1, biconical dipole lower oscillator 2, metal sleeve 3, and coaxial serial-parallel feeding network 4.

[0007] The tapered structure of the radiator of the biconical dipole antenna unit enables it to achieve better impedance matching with free space; the coaxial metal sleeve outside the radiator further widens the antenna bandwidth.

[0008] Furthermore, the inner conductors of the power divider branches of each level of the coaxial series-parallel feeding network 4 are connected to the upper dipole 1 of the double cone dipole, and the outer conductors are connected to the lower dipole 2 of the double cone dipole. The entire coaxial series-parallel feeding network also serves as a structural support for the omnidirectional antenna.

[0009] Furthermore, the coaxial series-parallel feeding network 4 is composed of a coaxial impedance linear gradient transformation section 4-1, a primary coaxial power divider 4-2 and a final coaxial power divider 4-3. The design method of first impedance transformation and then power division is adopted, and the one-to-eight coaxial power divider is regarded as a one-to-five unequal coaxial power divider and a one-to-four equal coaxial power divider connected in series. During the design, the structural dimensions of each output port and the intermediate impedance transformation section are obtained through reverse impedance matching analysis.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] The present invention realizes good omnidirectional performance and has the characteristics of ultra-wideband and high gain; the coaxial series-parallel feeding network has good impedance matching, low transmission loss, simple structure, and is easy to implement. It does not affect the omnidirectionality of the antenna and can be used as a structural support for the omnidirectional antenna. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagram of the biconical dipole shape of the antenna of the present invention;

[0013] Figure 2 It is a schematic diagram of biconical dipole feeding of the antenna of the present invention;

[0014] Figure 3 It is a schematic diagram of the coaxial series-parallel feeding network structure of the antenna of the present invention;

[0015] Figure 4 It is a schematic diagram of the biconical dipole structure of the antenna of the present invention;

[0016] Figure 5 It is an equivalent circuit diagram of the coaxial series-parallel feeding network of the antenna of the present invention;

[0017] Figure 6 is the reflection coefficient of the input port of the coaxial series-parallel feeding network of the antenna of the present invention;

[0018] Figure 7 is the transmission coefficient of the output port of the coaxial series-parallel feeding network of the antenna of the present invention;

[0019] Figure 8 is the reflection coefficient of the input port of the antenna of the present invention;

[0020] Fig. 9 is the horizontal plane radiation pattern of the center frequency f0 of the antenna of the present invention;

[0021] Fig.10 It is the vertical plane radiation diagram of the center frequency f0 of the antenna of the present invention.

[0022] Among them: 1, upper oscillator of double cone dipole; 2, lower oscillator of double cone dipole; 3, metal sleeve; 4, coaxial series-parallel feeding network; 4-1, coaxial impedance gradient transformation section; 4-2, primary coaxial power divider; 4-3, final coaxial power divider. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific implementation examples.

[0024] Reference Figure 1 A coaxial serial-parallel fed omnidirectional biconical dipole sleeve antenna is mainly composed of a sleeve biconical dipole antenna unit and a coaxial serial-parallel feeding network, which are biconical dipole upper oscillator 1, biconical dipole lower oscillator 2, metal sleeve 3, and coaxial serial-parallel feeding network 4 from top to bottom. The inner conductors of the power divider branches of each level of the coaxial serial-parallel feeding network 4 are connected to the biconical dipole upper oscillator 1, and the outer conductors are connected to the biconical dipole lower oscillator 2.

[0025] Reference Figure 2 and Figure 3 The coaxial series-parallel feeding network 4 is composed of a coaxial impedance gradient transformation section 4-1, a primary coaxial power divider 4-2, and a final coaxial power divider 4-3.

[0026] Example 1

[0027] Reference Figure 4 , the biconical dipole antenna unit uses the gradient structure of the radiator to achieve a better match between the impedance transformation of the feed port and the free space. The upper and lower radii of the biconical dipole are a and b respectively, and the height is h2; the coaxial metal sleeve outside the radiator further widens the antenna bandwidth, and the radius of the sleeve is d and the height is h3. When the total height remains unchanged, the matching and radiation performance of the antenna is mainly determined by the ratio of the total height of the sleeve antenna to the sleeve height h3. This ratio has an optimal value. Under this optimal ratio, the bandwidth of the antenna is the widest. There is also an optimal ratio between the radius b of the sleeve and the radius a of the inner conductor. When other parameters are given, adjusting the value of b can effectively change the impedance bandwidth of the antenna.

[0028] Reference Figure 5, the branches of the two-stage power divider of the coaxial series-parallel feeding network 4 are directly connected to the antenna, and the mutual coupling at the output end does not have a great influence on the transmission. In order to simplify the design, no isolation resistor is used to improve the isolation of the output end. The input power P0 is unequally divided according to 1:1:1:1:4, and then the branch P0 / 4 in the primary coaxial power divider is divided into four equal parts, thus forming a one-to-eighth equal part. If the characteristic impedance of the input and output of the coaxial power divider is Z0, the final coaxial power divider can be considered as a one-to-four equal coaxial power divider, and its input characteristic impedance Z in2 Can be done through Z in2 =Z 05 / / Z 06 / / Z 07 / / Z 08 , Knowable The primary power divider can be regarded as a one-to-five unequal coaxial power divider. so

[0029] The antenna in implementation case 1 is simulated using commercial simulation software. First, the coaxial series-parallel feeding network 4 is simulated, and the simulation results are the electrical reflection coefficient of the input port and the transmission coefficient of the output port of the coaxial series-parallel feeding network; then the coaxial series-parallel feeding omnidirectional biconical dipole sleeve antenna is simulated, and the simulation results are the input port reflection coefficient, the horizontal plane radiation pattern of the center frequency f0, and the vertical plane radiation pattern of the antenna of the present invention.

[0030] Reference Figure 6 The coaxial series-parallel feeding network 4 works in the L band, and the input port reflection coefficient ratio is less than -10dB in the frequency range of 0.55*f0 to 1.45*f0, and has good impedance matching characteristics.

[0031] Reference Figure 7 The simulation results are the transmission coefficients of the eight output ports of the coaxial series-parallel feeding network, S21~S51 are the transmission coefficients of the output ports of the primary coaxial power divider, S61~S91 are the transmission coefficients of the output ports of the final coaxial power divider, the amplitude consistency of the output ports of the same level is good, and the amplitude difference between the primary and final output ports is within 0.5dB.

[0032] Reference Figure 8 , the simulation result is the reflection coefficient of the input port of the antenna of the present invention, and the working bandwidth of the antenna is in the frequency range of 0.9*f0~1.1*f0;

[0033] Reference Fig. 9 and Fig.10 , are respectively the horizontal plane radiation pattern and the vertical plane radiation pattern of the center frequency f0 of the antenna of the present invention.

[0034] In summary, the present invention is used to design a coaxial series-parallel fed omnidirectional biconical dipole sleeve antenna, and the array is formed in the vertical direction to achieve the high gain characteristics of the omnidirectional antenna. The input end of the feeding network adopts 50 ohm coaxial feeding, and the coaxial series-parallel feeding network is composed of an impedance linear gradient transformation section and a two-stage coaxial power divider. It has good impedance matching, low transmission loss, simple structure, and is easy to implement. It overcomes the influence of the feeding network on the omnidirectionality of the antenna and can serve as a structural support for the omnidirectional antenna.

Claims

1. A coaxial series-parallel fed omnidirectional biconical dipole sleeve antenna, characterized in that: The antenna is composed of a sleeve biconical dipole antenna unit and a coaxial serial-parallel feeding network, which are, from top to bottom, the biconical dipole upper oscillator (1), the metal sleeve (3), the coaxial serial-parallel feeding network (4), and the biconical dipole lower oscillator (2); the coaxial serial-parallel feeding network (4) is a one-to-eight coaxial power divider, which is composed of a coaxial impedance linear gradient transformation section (4-1), a primary coaxial power divider (4-2), and a final coaxial power divider (4-3); the primary power divider (4-2) is a one-to-five unequal coaxial power divider, and the final coaxial power divider (4-3) is a coaxial power divider. (4-3) is a one-to-four coaxial power divider; the input power P0 is input from the coaxial port of an antenna, and is divided unequally in the ratio of 1:1:1:1:4 in the primary power divider (4-2) through the coaxial impedance linear gradient transformation section (4-1); the final coaxial power divider (4-3) further divides the 4P0 / 8 branch in the primary power divider (4-2) into four equal parts, thereby forming a one-to-eighth coaxial power divider; the inner conductors of the power divider branches of each level of the coaxial series-parallel feeding network (4) are connected to the upper oscillator (1) of the double-cone dipole, and the outer conductors are connected to the lower oscillator (2) of the double-cone dipole.

Images