RU2552230C2 - Directional band antenna - Google Patents

Abstract

FIELD: physics, communications.

SUBSTANCE: invention relates to antenna engineering and can be used in communication equipment, radar and navigation as a single broadband radiator or as a component of multielement antenna arrays, preferably for the upper part of the decimetre range. The directional band antenna comprises at least one zigzag printed radiator made on one side of a dielectric plate, placed in parallel to a flat reflector, a matching device and a coaxial line which extends to the zero potential point of the radiator. The matching device is in the form of a microstrip transmission line located between the coaxial line and the radiator and formed by portions of different width. The microstrip line is located on the other side of the dielectric plate over the radiator strips which form the return conductor of the microstrip line. The width of the portion of the microstrip line is selected based on a condition of matching the input resistance of the radiator and the coaxial line. The radiator strips have the same width throughout the length of the strip in order to stabilise the input resistance of the radiator.

EFFECT: enabling matching of a zigzag radiator with a coaxial feed line with any wave impedance, preventing cross polarisation interference in the feed and matching line, simple design and improved manufacturability of the both an antenna with a single radiator and antenna arrays.

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Description

FIELD OF THE INVENTION

The invention relates to antenna technology and can be used in communication, radar and navigation equipment as a single broadband emitter or as an integral element of multi-element antenna arrays, preferably for the upper part of the decimeter range.

State of the art

A known antenna containing at least one printed radiator with a power supply coaxial cable, a connector for receiving and transmitting equipment and a flat reflector (patent RU 2225663, IPC H01Q 1/38, publ. 10.03.2004).

The printed version of the emitters provides low metal consumption, weight and dimensions of the antenna. However, the aforementioned antenna has a significant drawback - a narrow matching range, which is due to the implementation of the emitter in the form of a strip vibrator. In addition, when using vibrator emitters as elements of an antenna array, to ensure unidirectional radiation, boards with emitters must be fixed orthogonally to the plane of the common reflector, which creates difficulties in ensuring the mechanical strength of the antenna.

Known panel antenna having a wide range of radiation (see patent RU 2273079, IPC H01Q 21/08, publ. 03/27/2006), consisting of one or more emitters powered by a coaxial cable, each of which is made in the form of a flat mounted parallel to the reflector a metal frame with a slit and four loops in the form of plates to improve the matching of the emitter.

However, these loops provide coordination in a limited frequency band and at the same time create radiation orthogonal, relative to the radiation of the frame, polarization, which contributes to the appearance of cross-polarization interference. Placing a coaxial cable in the radiation field also leads to cross-polarization interference and distortion of the radiation patterns of the emitter. To reduce phase distortion in the power supply of the emitter, the braid of the coaxial cable should be soldered to the frame along the entire length of the contact, which creates certain technological difficulties.

For matching with the supply line of an arbitrary wave resistance, an additional matching device will be required.

The radiation pattern of the antenna array and, therefore, its directional coefficient are determined by the directional properties of the emitters, their location in the array, as well as the distribution law of the amplitudes and phases of the supply signals. To ensure these requirements, especially in the upper part of the decimeter range, it is necessary to set tight tolerances on the geometric dimensions of the emitters, matching devices, power lines, as the size mismatch leads to changes in the shape of the radiation pattern, a decrease in the coefficient of directional action.

In order to obtain a frame antenna with good repeatability in the aforementioned solution, it is necessary to use laser cutting or an adjustable stamp in its manufacture, which leads to a significant increase in the cost of production.

When creating highly directional antennas with a large number of emitters, the use of multi-element antenna arrays based on printed emitters having good repeatability of geometric dimensions is more promising.

Known broadband zigzag antenna (see patent RU 2373619, IPC H01Q 9/16, publ. November 20, 2009), containing a printed vibrator consisting of two identical metal shoulders of a ring-shaped elliptical shape, located symmetrically relative to the power points, and two matching elements in the form of conductive planes of elliptical shape, placed with a constant gap inside the shoulders of the vibrator, on the same side of the dielectric plate. This antenna can be used as a radiator of a multi-element array. To organize the power supply of the symmetric emitter with a coaxial cable, there is an additional balancing device located perpendicular to the board.

The disadvantage of this design is the difficulty of implementing a balancing device, because the latter has a length of 0.25λ, where λ is the wavelength at the middle frequency of the operating range, and the distance to the reflector is only (0.16-0.18) λ. As a result, it is impossible to fix the balancing device directly to the reflector. In addition, the antenna has a small gain (not more than 7 dB) and a matching band of 50-55%.

Known range directional antenna printed design (see patent RU 2076407, IPC H01Q 19/10, publ. 03/27/1997) containing a metal zigzag radiating fabric degenerated into a ring filled with two metal sectors with an angle β at the power terminals, and a flat screen reflector parallel to the emitter. This antenna can also be used as a radiator of a multi-element array, however, it has a low level of matching and a low gain (about 4 dB).

As the closest analogue, characterized by a combination of features closest to the set of essential features of the claimed technical solution, the design of the zigzag antenna is disclosed in the patent for invention SU 1617501, IPC H01Q 19/00, publ. 12/30/1990

The aforementioned antenna comprises a zigzag printed emitter made on one side of the dielectric board, a flat reflector placed parallel to the emitter, a matching device and a coaxial power line.

The emitter is formed by a pair of zigzag strips connected by ends to form two rhombic cells located symmetrically relative to the supply points. The use of a zigzag emitter above the reflector allows to obtain a gain of 8-9 dB in the working frequency band.

A coaxial cable supplying the emitter is laid on one side of the diamond-shaped section. To obtain stable parameters in this antenna, it is necessary to solder the cable braid to the diamond-shaped section along the entire length, since the arbitrary position of the cable relative to the conductors of the diamond-shaped section will lead to phase instability of the signal supplying the emitter, which is unacceptable in multi-element gratings. The implementation of antennas and antenna arrays with such a design of the emitter is fraught with technological difficulties, because it is necessary to achieve repeatability of the location of the cable on the emitter.

Another significant disadvantage of the antenna of patent SU 1617501 is a complex matching device made in the form of metal tape conductors located on both sides of the board and having electromagnetic coupling with the emitter. Mentioned tape conductors create radiation orthogonal, relative to the emitter, polarization, which contributes to the appearance of cross-polarization interference.

Disclosure of invention

The technical problem to which the claimed invention is directed is to solve the problems of matching a zigzag printed radiator with a coaxial power line of arbitrary wave impedance and eliminating cross-polarization interference while maintaining a high gain and a wide operating frequency range. As well as improving the manufacturability of the antenna.

The technical problem is solved due to the fact that in a band directional antenna containing at least one zigzag printed emitter made on one side of a dielectric board placed parallel to a flat reflector, a matching device and a coaxial line for supplying the emitter, according to the claimed invention, a coaxial line brought to the point of zero potential of the emitter, and the matching device is made in the form of a microstrip signal transmission line from the coaxial line to the emitter Formed by portions of varying width and disposed on the second side of the dielectric board of the emitter strips, which form the return conductor of the microstrip line, the microstrip line width of portions selected based on the condition matching the input impedance of the radiator and the coaxial line.

The above set of essential distinguishing features of the claimed technical solution allows to obtain the following positive technical results:

- providing the possibility of matching a zigzag emitter with a coaxial power line with any impedance;

- elimination of cross-polarization interference in the power line and matching;

- simplification of the design;

- increase the manufacturability of manufacturing both an antenna with a single emitter and antenna arrays;

- ensuring high mechanical strength of the antenna.

The main difference between the proposed device and the prototype is the design of the matching device in the form of a microstrip line, which ensures the transmission of the signal from the coaxial power line to the emitter and does not create cross-polarized radiation.

The microstrip line is made on the side of the dielectric board opposite to the emitter and is located directly above the emitter strips, i.e. repeats the outlines of the radiating part, above which it is located, and parallel to them.

Such a design of the matching device made it possible, firstly, to remove the coaxial power line beyond the action of the emitter — to the point of zero potential, so that it does not create additional cross-polarization radiation. Secondly, the asymmetric microstrip line itself generates radiation consistent with the polarization emitter, which also eliminates the appearance of cross-polarization interference.

At the same time, the proposed design of the matching device allows the use of a coaxial line with any arbitrarily specified wave impedance, and not just a standard coaxial cable, as a coaxial power supply line for the emitter. By varying the width of the strip of the signal wire of the matching device (the width of the sections of the microstrip line), they achieve coordination of the input impedance of the emitter with the coaxial line in a wide band of operating frequencies.

In fact, the microstrip line is an input matching resistance transformer, which can be either single-stage or multi-stage, depending on the width of the operating frequency range or level of matching (see, for example, Prince A.L. Feldstein, L.R. Yavich, V.P. Smirnov. A Guide to Elements of Waveguide Technology, Sovetskoe Radio Publishing House, Moscow, 1967, p. 270-345). The calculation of the width of the microstrip line can be performed, for example, using the Passive Circuits section of the AppCad program (Agilent Technologies).

The possibility of using arbitrary wave impedance coaxial for powering the emitter can significantly simplify and increase the manufacturability of antenna arrays by significantly simplifying the matching of the input impedance of the emitter with the signal distribution scheme over the emitters of the array.

The emitter strips perform not only their direct radiation function, but also form the return wire of the microstrip line, which can significantly simplify the design of the matching device and the antenna as a whole. In this case, the minimum width of the strips of the emitter is selected sufficient to create the return wire of the microstrip line.

The emitter strips in combination with the microstrip line form the antenna balancing device.

The emitter strips also have an unequal stripe width, which makes it possible to achieve stability of the input impedance of the emitter in the operating frequency range.

The dielectric board with the emitter and matching device is fixed to the reflector at points of zero potential by means of racks.

In a preferred embodiment of the device, the coaxial power line of the emitter is made in the form of one of the racks for fixing the emitter to the reflector. The hollow tubular housing of the rack forms an external coaxial wire and is fixed by means of flanges on one side to the reflector and, on the other hand, to the emitter strips at the point of zero potential. The central conductor of the coaxial, missed inside the tubular body, is connected at one end to the microstrip line, and the other to the central contact of the high-frequency connector (in the case of a single emitter) or to the signal conductor of the strip pattern of the distribution and matching of the antenna array.

The aforementioned pattern of distribution and matching of the antenna array is a printed circuit board, which is fixed on the back of the reflector.

Thus, the proposed antenna is characterized by high mechanical strength of the structure, the absence of transitional devices and high adaptability.

Brief Description of the Drawings

The feasibility of the industrial feasibility of the proposed technical solution is confirmed by the following example, illustrated by drawings, where:

figure 1 - shows an antenna with one emitter, General view, isometry;

figure 2 is a view of the printed circuit board from the side of the emitter.

The implementation of the invention

The directional antenna (see Fig. 1) contains a dielectric board 1 with a zigzag printed emitter and matching device, a flat reflector 2 placed parallel to the board 1, and a coaxial line 3.

The zigzag printed emitter 4, located on the side A of the dielectric board 1, consists of two zigzag strips 5 and 6, connected by ends to form two identical rhombic cells located symmetrically relative to the power points (see figure 2).

On the B side of the dielectric board 1, above the strips of the emitter 4, there is a microstrip line 7 (MPL) connecting the supply point 8 of the emitter 4 with a coaxial line 3 brought to the point of zero potential 9 of the emitter.

MPL 7 is formed by linear sections of different widths. Varying the width of the sections of the microstrip line 7, they achieve coordination of the input impedance of the emitter with the coaxial power line 3 with any wave impedance over the entire operating frequency range. The possibility of using a coaxial of arbitrary wave resistance can significantly simplify and increase the manufacturability of manufacturing antenna arrays.

The width of the strips 5 and 6 of the emitter is also performed unequally in different areas along the length of the strips.

Firstly, the minimum strip width is selected sufficient to create the return wire of the microstrip line 7, while the calculations are performed by known methods (for example, see Prince LN Kechiev. Designing printed circuit boards for digital high-speed equipment. ITD Group LLC, Moscow , 2007, p. 218-220).

Secondly, the width of strips 5 and 6 should ensure the stability of the input impedance of the emitter in the operating frequency range.

The dielectric board 1 is fixed to the reflector 2 at points of zero potential by means of racks 10 and 11.

In one example of the implementation of the antenna, the coaxial line 3 is passed inside the rack 10, while the outer conductor of the coaxial has contact with the radiating part at the point of zero potential 9, and the internal one is soldered to the microstrip matching line 7.

In another example implementation of the antenna, the coaxial line 3 is made in the form of a rack 10. In this case, the hollow tubular body of the rack forms an external coaxial wire, which is fixed by means of flanges on one side to the reflector 2, and on the other hand, to the strips of the emitter 4 at the point of zero potential . The central conductor of the coaxial, passed inside the tubular body, is soldered at one end to the microstrip line 7, and the other to the central contact of the high-frequency connector or to the signal conductor of the strip distribution and matching antenna array located on the back of the reflector 2 (not shown in the drawings).

The proposed technical solution can be used both in an antenna with a single emitter, and in complex antenna systems with multi-element arrays with linear or spatial arrangement of emitters, depending on the desired shape of the antenna pattern.

The antenna generates directional radiation in a wide frequency range and has a high gain of 8-9 dB. The antenna works as follows.

The signal from the coaxial line 3 is transmitted to the microstrip line 7, which excites the emitter 4. In this case, the asymmetric microstrip line 7 of the matching device has radiation that is consistent with the polarization emitter 4, which eliminates the appearance of cross-polarization interference. Due to the fact that the coaxial line 3 is removed from the coverage area of the emitter, it does not create additional cross-polarized radiation.

Claims (3)

1. A directional antenna containing at least one zigzag printed emitter made on one side of a dielectric board parallel to a flat reflector, a matching device and a coaxial line for powering the emitter, characterized in that the coaxial line is brought to the point of the transmitter’s zero potential and the matching device is made in the form of a microstrip signal transmission line from the coaxial line to the emitter, formed by sections of different widths and placed on watts swarm dielectric board side strips over the emitter forming the return conductor of the microstrip line, the microstrip line width of portions selected based on the condition matching the input impedance of the radiator and the coaxial line. 2. The antenna according to claim 1, characterized in that the emitter strips are made with an unequal length of the strip width to stabilize the input impedance of the emitter. 3. The antenna according to claim 1, characterized in that the coaxial power line of the emitter is made in the form of a rack for fixing the emitter to the reflector, the hollow tubular body of which forms an external coaxial wire, attached to the reflector on one side and the strips of the emitter on the other side, and the central conductor of the coaxial, missed inside the tubular body, is connected at one end to the microstrip line, and the other to the central contact of the high-frequency connector or to the signal conductor of the strip distribution circuit and asovaniya array antenna placed on the back of the reflector.

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