CN106229635B - A kind of omnidirectional's dual circularly polarized antenna of ipsilateral feed - Google Patents

Abstract

The present invention provides an omnidirectional dual circularly polarized antenna fed from the same side, comprising: a radiation structure, a coaxial-like impedance matching structure, and a radio frequency excitation switching T-shaped connection structure, and the coaxial-like impedance matching structure is divided into the following A similar coaxial impedance matching structure and a lower coaxial impedance matching structure, the upper and lower ends of the radiation structure are respectively connected to the lower end of the upper coaxial impedance matching structure and the upper end of the lower coaxial impedance matching structure, the upper coaxial impedance The upper end of the matching structure is closed with a metal disc, and the lower end of the coaxial impedance matching structure is connected to the RF excitation conversion T-connection structure. The interface of the RF excitation conversion T-connection structure can directly use the SMA connector feeder for RF excitation. The present invention has good omnidirectional performance and axial ratio performance, and has a certain working bandwidth, a -10dB bandwidth of 600M (5.2GHz-5.8GHz), and an in-band gain greater than 5.2dB, up to 6.7dB.

Description

An Omnidirectional Dual Circularly Polarized Antenna Feed from the Same Side

technical field

The present invention relates to an antenna, in particular to an antenna capable of realizing omnidirectional dual circular polarization by feeding on the same side.

Background technique

Circularly polarized antennas are more and more widely used because of their ability to receive and transmit incoming waves with arbitrary polarization. In many application scenarios, received and transmitted signals come from all directions. In order to better handle these signals, omnidirectional circular polarization performance must be achieved. However, the gain reduction due to omnidirectional is more obvious.

After literature search, the article "Wideband Omnidirectional Circularly Polarized Patch AntennaBased on Vortex Slots and Shorting Vias" published in IEEE Trans.Antennas Propag. in 2014 by Dan Yu, Shu-Xi Gong et al. proposed an omnidirectional circularly polarized For the antenna, although the 10dB impedance bandwidth reaches 51.7%, and the 3dB axial ratio bandwidth also reaches 57.8%, the in-band gain is less than 2dBic.

In addition, even if a high omnidirectional gain and dual circular polarization characteristics can be achieved, it is still a problem to ensure that the dual circular polarizations do not interfere with each other. After literature search, the article "Dual Circularly Polarized Omnidirectional Antenna with Slot Array on Coaxial Cylinder" published by Zhou Bin, Junping Geng and others in the International Journal of Antennas and Propagation in 2015 proposed an omnidirectional dual circularly polarized antenna, although In the frequency band, the gain of about 5dBic and good circular polarization characteristics are realized. However, since the left and right circular polarization feed ports are distributed at both ends of the antenna, if the antenna wants to achieve horizontal omnidirectional circular polarization, the antenna must be placed vertically. At present, it is more convenient to use a cable to connect the lower feeder port, but the drooping part of the cable connected to the upper feeder port will definitely affect the radiation pattern, thus destroying the circular polarization characteristics of the loop antenna, resulting in the antenna needing to implement different circular poles. It needs to be reinstalled when upgrading, which brings inconvenience to users.

Contents of the invention

In view of the defects in the prior art, the object of the present invention is to provide an omnidirectional dual circularly polarized antenna with a certain working bandwidth. The -10dB bandwidth of the antenna reaches 10.9%, and the horizontal omnidirectional axial ratio within the entire bandwidth is less than 3dB, the horizontal omnidirectional gain in the band is greater than 5.2dB, and the highest gain reaches 6.7dB.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

An omnidirectional dual circularly polarized antenna fed from the same side, comprising: a radiation structure, a coaxial-like impedance matching structure, and a radio frequency excitation conversion T-shaped connection structure, and the coaxial-like impedance matching structure is divided into the above-mentioned coaxial impedance matching structure A matching structure and a lower-type coaxial impedance matching structure, the upper and lower ends of the radiation structure are respectively connected to the lower end of the upper-type coaxial impedance matching structure and the upper end of the lower-type coaxial impedance matching structure, and the upper end of the upper-type coaxial impedance matching structure Closed with a metal disc, the lower end of the lower coaxial impedance matching structure is connected to the RF excitation conversion T-connection structure, and the interface of the RF excitation conversion T-connection structure can directly use the SMA connector feeder for RF excitation.

The radiating structure includes an inner conductor of the radiating structure, an outer conductor of the radiating structure, and an inner core, all of which are metal cylinders, the top of the inner core is connected to the metal disc, and a certain distance is separated between the inner conductor of the radiating structure and the top of the radiating structure to provide energy inflow/ outflow channel.

A medium is filled between the inner conductor and the outer conductor of the radiating structure, and between the inner conductor and the inner core of the radiating structure.

The outer wall of the radiation structure is provided with two rectangular gaps forming 90 degrees to each other,

A plurality of said slits are opened around the outer wall of the radiation structure, and the upper and lower groups radiate electromagnetic waves outward.

The quasi-coaxial impedance matching structure includes a matching structure inner conductor, a medium, and a matching structure outer conductor, and the matching structure inner conductor is a plurality of metal cylinders with different outer diameters and lengths.

A medium is filled between the inner conductor and the outer conductor of the matching structure.

The radio frequency excitation conversion connection T-shaped structure has two ports, wherein the feed-down port is connected to the inner conductor and the inner core of the radio frequency excitation conversion connection T-shaped structure; The inner conductor is connected, and the side feed port is a gradual coaxial line structure as a whole, and both ports can be connected to standard SMA heads.

The antenna is fed from the lower feed port from the T-shaped connection structure, and the energy propagates upward from the medium between the inner core and the inner conductor to the medium part between the inner conductor and the outer conductor (because the inner conductor is not connected to the top metal disc connection, so that the inner and outer media are connected), and then propagate downwards while radiating through the gap to realize left-handed circular polarization. Feed from the side-feed port of the T-shaped connection structure, the energy is transmitted from the tapered coaxial line into the medium between the inner and outer conductors, and propagates upward while radiating energy from the gap to realize right-handed circular polarization.

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

1. The omnidirectional dual circularly polarized antenna of the present invention has higher efficiency and better isolation between two ports, thus having higher gain.

2. The present invention has good omnidirectional performance.

3. The present invention has a wider -10dB bandwidth of 10.9%.

4. The down-feed port and side-feed port of the T-shaped connection structure of the present invention can be directly connected to the SMA head, which is convenient for connection and use.

5. The distance between the two feed points of the T-shaped connection structure of the present invention is relatively close and the isolation is good, and the left and right circular polarization can be conveniently realized according to the needs. It avoids the impact on the circular polarization performance caused by the feed point at both ends of the antenna which may cause simultaneous operation.

Description of drawings

Other characteristics, objects and advantages of the present invention will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 is the structural representation of omnidirectional dual circularly polarized antenna of the present invention;

Figure 2 is an exploded view of Figure 1;

Fig. 3 is a sectional view along A-A of Fig. 1;

Fig. 4 is a sectional view along B-B of Fig. 1;

5 is a return loss diagram of an omnidirectional dual circularly polarized antenna according to an embodiment of the present invention;

FIG. 6 is a horizontal omnidirectional axial ratio diagram of three frequency points between 5.2GHz, 5.5GHz, and 5.8GHz according to an embodiment of the present invention;

FIG. 7 is a horizontal omnidirectional gain diagram of three frequency points between 5.2GHz, 5.5GHz and 5.8GHz according to an embodiment of the present invention.

In the figure: 1 is the radiation structure of the antenna, 2 is the coaxial impedance matching structure of the antenna, 3 is the RF excitation conversion T-shaped connection structure, 4 is the upper and lower slots of one group of radiation units, 5 is the radiation slot array, and 6 is the antenna The outer conductor of the radiation structure, 7 is the filling medium of the antenna radiation structure (including the medium between the outer conductor and the inner conductor and the medium between the inner conductor and the inner core), 8 is the inner conductor of the antenna radiation structure, and 9 is the radio frequency excitation conversion T-type The outer conductor of the connection structure, 10 is the filling medium of the radio frequency excitation conversion T-shaped connection structure, 11 is the inner conductor of the radio frequency excitation conversion T-shaped connection structure, 12 is the downfeed port of the radio frequency excitation conversion T-shaped connection structure, and 13 is the radio frequency excitation conversion T-shaped connection Structure side feed port, 14 is the inner conductor of the upper matching structure, and 15 is the inner conductor of the lower matching structure.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

Please refer to Figs. 1 to 4 at the same time, the omnidirectional dual circularly polarized antenna provided by the present invention includes: 1, antenna radiation structure, 2, similar coaxial impedance matching structure, 3, radio frequency excitation conversion T type connection structure. The upper end of the above-mentioned coaxial impedance matching structure is closed with a metal disc, and the lower end is connected to the antenna radiation structure. The lower end of the antenna radiation structure is connected with a similar coaxial matching structure. The following type of coaxial matching structure is terminated with a radio frequency excitation conversion T-shaped connection structure. The lower end and side end of the RF excitation conversion T-shaped connection structure can directly use the SMA connector feeder for RF excitation.

Further, the antenna radiation structure 1 is a similar (similar) dual-coax structure, and the outer conductor 6 of the radiation structure is metal, with a thickness of 1.5 mm, a diameter of 25 mm, and a length of 150.9 mm. There are 4 rectangular slits with an included angle of 90 degrees), 4 in a week, and 4 groups up and down to form a radiation slit array. 8 is the inner conductor of the antenna radiation structure, with a diameter of 1.5 mm and the same length as the outer conductor, and a medium 7 is filled between the inner and outer conductors. The medium is Teflon with a dielectric constant of 2.1. The radius of the inner core is 0.46mm and the length is equal to that of the outer conductor.

Further, the coaxial-like (similar) impedance matching structure 2 is directly connected to the upper and lower sides of the radiating structure 1, and the outer conductor of the matching structure is connected to the outer conductor 6, the inner core, and the inner conductor of the radiating structure. The inner conductor 14 of the upper matching structure and the inner conductor 15 of the lower matching structure of the upper and lower coaxial impedance matching structures are three sections of metal cylinders with different diameters, and the inner diameter is equal to the outer diameter of the inner conductor. The diameters of the metal rings used as the internal conductors of the matching structure are 3.7mm, 6.0mm, and 6.5mm, and the lengths are 7.9mm, 6.0mm, and 6.5mm respectively; the diameters of the three metal rings of the lower coaxial impedance matching structure are 3.2mm. , 7.4mm, 6.9mm, and the lengths are 8.1mm, 5.5mm, and 8.1mm respectively. They are directly connected, and the impedance transformation is realized by the transmission line theory. The filling medium 10 between the inner conductor and the outer conductor of the matching structure is Teflon.

Further, the RF excitation conversion T-shaped connection structure 3 is connected under the coaxial impedance matching structure of the following type, the outer conductor of the coaxial impedance matching structure of the following type is connected with the cylindrical joint at the lower end of the T-shaped head through a gradual structure, and the thickness is similar to the coaxial impedance The outer conductor of the matching structure is the same. The outer conductor 9 contained in the cylindrical joint at the lower end of the T-shaped head and the thickness of the inner diameter of the inner core are the same as those in the radial structure and the quasi-coaxial impedance matching structure. The joint on the side of the T-shaped head is a gradual coaxial cable structure, and the inner core is connected to the outer conductor 9 in the lower end of the T-shaped head. The diameter is the same as that of the outer conductor, and then gradually changes to a standard SMA interface. Both the lower end connector and the side end connector of the T-shaped head can be directly connected with the SMA connector.

The working principle of the omnidirectional dual circular polarization of the present invention is as follows:

As shown in Figures 1 to 4, the omnidirectional dual circularly polarized antenna provided by the present invention can realize left-handed and Right-handed circular polarization properties. The antenna is fed from the feed-down port of the T-shaped connection structure, and the energy propagates upward from the medium between the inner core and the inner conductor to the medium part between the inner conductor and the outer conductor (because the inner conductor is not connected to the top metal disc, Make communication between the inner and outer media), and then propagate downwards while radiating through the gap to realize left-handed circular polarization. Feed from the side-feed port of the T-shaped connection structure, the energy is transmitted from the tapered coaxial line into the medium between the inner and outer conductors, and propagates upward while radiating energy from the gap to realize right-handed circular polarization.

Specifically as shown in Figure 4, the RF excitation signal is fed to the antenna through the feed-down port 12 in Figure 4, and the signal first passes through the inner core and the RF excitation conversion T-shaped connection structure inner conductor 11 and the medium 10 between them. The axial structure propagates upwards, spreads outward after reaching the top of the antenna, and starts to propagate downward along the coaxial structure composed of inner conductor, outer conductor and the medium between them. Due to the impedance mismatch between the internal and external coaxial structures, the impedance matching structure of the above coaxial structure is first used to make the S11 less than -10dB in the range of 5.2GHz-5.8GHz to achieve impedance matching. The signal is radiated outward from the slot array on the radiation structure 1, so that there is a higher gain. The energy starts to radiate outward from the first slot, and there is very little energy at the fourth slot, so that only a little energy enters the T-shaped structure side feed port, so that the isolation between the two ports is better. If a higher gain needs to be achieved, the number of radiation slots can be appropriately increased.

Similarly, the radio frequency excitation signal is fed to the antenna through the side feed port 13 in Fig. 4, and the signal is transmitted to the radiator through the tapered coaxial line, and enters the outer coaxial line structure composed of the inner conductor, the outer conductor and the medium between them Propagate upward, radiating energy outward from the gap as it propagates. Due to the mismatch between the impedance of the tapered coaxial line (T-shaped structure) and the coaxial structure outside the class, first go through the following coaxial matching structure, so that the S22 is less than -10dB in the range of 5.2GHz-5.8GHz, which is similar to the coaxial matching structure The design is based on transmission line theory to achieve impedance matching. Signals are radiated outward from the four groups of slot arrays 5 on the radiation structure 1, so that there is a relatively high gain. Energy starts to radiate outward from the fourth slot, and there is very little energy at the first slot, so that only a little energy enters the inner coaxial structure until the feed-down port 12, so that the isolation between the two ports is better.

As shown in FIG. 5 , the return loss diagram obtained by the simulation of this embodiment is shown. It can be seen from the figure that the return loss is less than -10dB in the 5.2GHz-5.8GHz frequency band.

As shown in FIG. 6 , the axial ratio diagrams obtained by the simulation of this example at three frequency points of 5.2GHz, 5.5GHz, and 5.8GHz are horizontally omnidirectional (Theta=90°). It can be seen from the figure that in the 5.2GHz-5.8GHz frequency band, the maximum average value of the axial ratio is basically below 3dB.

As shown in FIG. 7 , the gain diagram obtained by the simulation of this example at three frequency points of 5.2GHz, 5.5GHz, and 5.8GHz is horizontally omnidirectional (Theta=90°). It can be seen from the figure that in the 5.2GHz-5.8GHz frequency band, the minimum value of the gain is greater than 5.2dB, and the maximum value reaches 5.7dB, and the omnidirectional performance of the antenna is good.

Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art may make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. In the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims (2)

1. an omnidirectional dual circularly polarized antenna fed from the same side is characterized in that it comprises: radiation structure, similar coaxial impedance matching structure, radio frequency excitation conversion T-type connection structure, and described similar coaxial impedance matching structure is divided into It is an upper-type coaxial impedance matching structure and a lower-type coaxial impedance matching structure, and the upper and lower ends of the radiation structure are respectively connected to the lower end of the upper-type coaxial impedance matching structure and the upper end of the lower-type coaxial impedance matching structure. The upper end of the axial impedance matching structure is closed with a metal disc, and the lower end of the lower coaxial impedance matching structure is connected to the radio frequency excitation conversion T-shaped connection structure. The inner conductor and the inner core of the excitation conversion T-shaped connection structure; the inner core of the side feed port is connected with the inner conductor of the RF excitation conversion T-type connection structure of the down feed port. Use SMA connector feeder for RF excitation; The radiating structure includes an inner conductor of the radiating structure, an outer conductor of the radiating structure, and an inner core, all of which are metal cylinders, the top of the inner core is connected to the metal disc, and a certain distance is separated between the inner conductor of the radiating structure and the top of the radiating structure to provide energy inflow/ For the outflow channel, a medium is filled between the inner conductor of the radiation structure and the outer conductor of the radiation structure, and between the inner conductor of the radiation structure and the inner core, and the outer wall of the radiation structure is provided with two rectangular gaps at 90 degrees to each other; The quasi-coaxial impedance matching structure includes an inner conductor of the matching structure, a medium, and an outer conductor of the matching structure. The inner conductor of the matching structure is a plurality of metal cylinders with different outer diameters and lengths. A dielectric is filled between the conductors. 2 . The omnidirectional dual circularly polarized antenna fed from the same side according to claim 1 , wherein a plurality of rectangular slots are opened around the outer wall of the radiation structure, and multiple groups of upper and lower groups radiate electromagnetic waves outward. 3 .