RU2812810C2 - Method for exciting slot antenna with multi-loop conductor and device for its implementation - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: invention relates to a method for exciting a slot antenna and a device for its implementation and is used in antenna-feeder devices. The technical result is an expansion of the tuning range of the slot antenna and ease of adjustment of the matching of the slot antenna with the feeder. The result is achieved by the fact that the slot antenna is excited by a multi-loop conductor, while N are made in the conducting plate with the slot, where N≥1, holes on one side and M, where M≥1, holes on the other side relative to the longitudinal axis of the slot, the outer conductor of the coaxial feeder is galvanically connected to a plate with a slot in the area of one of the holes from a set of N holes, the central conductor and the dielectric of the feeder are inserted in series into N holes to form N-1 loops, then laid above or below the slot to form a loop, inserted sequentially into the M holes to form M-1 loops.

EFFECT: expansion of the tuning range of the slot antenna and ease of adjustment of the matching of the slot antenna with the feeder.

2 cl, 7 dwg

Description

Field of technology to which the invention relates

The present method of exciting a slot antenna and the device for its implementation relate to the field of radio engineering, namely to antenna-feeder devices.

State of the art

There is a known method for exciting a slot antenna [A.L. Drabkin, V.L. Zuzenko, A.G. Kislov "Antenna-feeder devices". M.: Soviet radio. - 1974; rice. XI.8 on page 241], a piece of conductor located between the long edges of the slit. The conductor section is powered, for example, by a coaxial cable, as follows: the coaxial cable is laid on a plate with a slot, the outer conductor of the coaxial cable is galvanically connected to the plate at a first point on the first long edge of the slot, the center conductor of the coaxial cable is galvanically connected to the first end of the said conductor section , the second end of which is in galvanic contact with the plate at a second point on the second long edge of the slot. The central conductor of the cable can be used as a section of conductor exciting the slot antenna after removing the sheath and outer conductor from the cable in the area between the edges of the slot. To ensure matching of the slot antenna with the coaxial cable, the points of galvanic contact of the outer conductor of the coaxial cable with the first long edge of the slot and the piece of conductor with the second long edge of the slot are shifted from the center of the slot towards the short edge of the slot (The second point of galvanic contact is located opposite the first point of galvanic contact) .

Disadvantages of the above-described method of exciting a slot antenna and the device for its implementation:

- narrow tuning range of the slot antenna with coaxial cable; hereinafter, by the tuning range of an antenna with a feeder, we mean the frequency range in which the VSWR in the feeder feeding the antenna at the tuning frequency will not exceed the permissible VSWR value _permissible . It is natural to strive to obtain a traveling wave mode (VSWR = 1) in the feeder at the tuning frequency,

- difficulty in finding the point of galvanic contact of the outer conductor of the coaxial cable with the plate on the first edge of the slot to ensure alignment of the slot with the coaxial cable; the mentioned complexity is due to the narrow matching frequency band,

- in the design of the slot antenna there is no possibility of compensating the reactive component of the antenna input impedance,

- due to asymmetric excitation of the antenna, a wave appears that propagates into the lines formed by the outer conductor of the coaxial cable and the plate; As a result, noticeable cable radiation is observed (feeder antenna effect), while the antenna characteristics significantly depend on external operational factors.

The closest to the claimed technical solution - the prototype - is the slot antenna according to the patent RU 2574172 C1 (RU 2574172 C1, H01Q 13/12 (2006.01), "SLIT CYLINDRICAL ANTENNA", Patent holder: FSBEI HPE "South Ural State University" (National Research University) (FSBEI HPE "SUSU" (National Research University)) (RU), Authors: Voitovich N.I., Klygach D.S., Nizametdinov D.I., Repin N.N.. The slot cylindrical antenna contains a conducting cylindrical body with a longitudinal slot with first and second long edges and a feeder, additionally comprising a first conductive clamp, a second conductive clamp and a matching section of cable, wherein the first clamp is located to form a galvanic contact on the first edge of the slot, the second clamp is located to form a galvanic contact on the second edge of the slot , the feeder is laid on the surface of the cylinder along a straight line diametrically opposite to the longitudinal axis of the slot, with a bend in the vicinity of the point of excitation of the slot, laid through the first clamp with the outer conductor of the feeder forming a galvanic contact with the first clamp, a matching section of cable is laid through the second clamp; the central conductor of the feeder is galvanically connected to the first end of the exciting conductor, the second end of which is connected to the central conductor of the matching cable section.

Disadvantages of the excitation method and the device for its implementation of the above-mentioned slot cylindrical antenna:

- narrow tuning range of the slot antenna with coaxial cable,

- the mentioned excitation device is applicable only for exciting a slot on a closed cylindrical surface,

- tuning a slotted cylindrical antenna to resonance by cutting the matching section of the cable causes a shift in the resonance of the slotted cylindrical antenna towards low frequencies; if it is necessary to reconfigure the antenna to resonance at the frequency of the original range, it is necessary to install a new matching section of cable into the design of the slotted cylindrical antenna,

- repeated tuning of a slotted cylindrical antenna to resonance in the frequency range leads to inefficient use of components due to the need to replace the matching cable section.

Disclosure of the Invention

The technical result of the proposed method of exciting a slot antenna and the device for its implementation is:

- expanding the tuning range of the slot antenna,

- in the convenience of setting up the coordination of the slot antenna with the feeder.

The technical result is achieved by introducing an additional multi-loop conductor into the antenna and adjusting the number and geometric dimensions of the loops of the multi-loop conductor.

The introduction of a multi-loop conductor into the slot antenna makes it possible to solve the following problems:

- settings for matching the slot antenna with the feeder in a wide frequency range,

- compensation of the reactive component of the input impedance of a slot antenna by changing the number and size of loops of a multi-loop conductor,

- ensuring the transmission of maximum microwave signal power by matching the slot antenna with the feeder,

- provides the ability to repeatedly tune the slot antenna to resonance in the operating frequency range.

The solution to the problems is illustrated below with drawings.

Brief description of drawings

In fig. Figure 1 shows a cross-section of a slot antenna excited by a three-loop conductor, a plane perpendicular to the long edges of the slot. The slot antenna is powered by a coaxial cable.

In fig. 1 the following notations are introduced:

1 - slot antenna excited by a three-loop conductor,

2 - conductive plate,

3 - slot,

4 - coaxial cable,

5 - first end of the coaxial cable,

6 - second end of the coaxial cable,

7 - radio frequency connector,

8 - three-loop conductor,

9 - holes in the plate on the first side relative to the longitudinal axis of the slot,

10 - holes in the plate on the second side relative to the longitudinal axis of the slot,

11 - outer conductor of the coaxial cable,

12 - galvanic contact of the outer conductor of the coaxial cable with the plate,

13 - central conductor of the coaxial cable,

14 - dielectric of a coaxial cable.

In fig. Figure 2 shows an assembled slot antenna excited by a multi-loop conductor.

In fig. Fig. 3 shows a slot antenna excited by a multi-loop conductor, assembled, with a feeder located on a conducting plate parallel to the longitudinal axis of the OO slot.

In fig. 4. shows a cross-section passing through the axis of a coaxial cable 4 feeding a slot antenna excited by a multi-loop conductor.

In fig. 5 shows the VSWR as a function of the frequency of a slot antenna excited by a multi-loop conductor according to the present invention.

In fig. 5 the following notations are introduced:

15 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the first configuration of a multi-loop conductor,

16 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the second configuration of a multi-loop element,

17 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the third configuration of a multi-loop exciting element,

18 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the fourth configuration of a multi-loop exciting element,

19 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the fifth configuration of a multi-loop exciting element,

20 - dependence of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for the sixth configuration of a multi-loop exciting element,

21 - envelope of the family of dependences of the VSWR of a slot antenna excited by a multi-loop conductor on frequency for a set of configurations of a multi-loop conductor.

In fig. Figure 6 shows the VSWR dependences of a “classical” slot antenna in the frequency range.

In fig. 6 the following notations are introduced:

22 - dependence of the VSWR of a “classical” slot antenna on frequency for the first position of the galvanic contact of the outer conductor and the central conductor at the edges of the slot of the prototype antenna,

23 - dependence of the VSWR of a “classical” slot antenna on frequency for the second position of the galvanic contact of the outer conductor and the central conductor at the edges of the slot of the prototype antenna,

24 - dependence of the VSWR of a “classical” slot antenna on frequency for the third position of the galvanic contact of the outer conductor and the central conductor at the edges of the slot of the prototype antenna,

25 - envelope of the family of dependences of the “classical” slot antenna on frequency for the set of contact positions of the outer conductor and the central conductor at the edges of the slot.

In fig. 7 shows for comparison the VSWR tuning ranges of a slot antenna excited by a multi-loop conductor according to the present invention and a “classical” slot antenna.

Carrying out the invention

Referring to FIG. 1, which is a cross-section of a slot antenna, with a three-loop conductor in a plane perpendicular to the long edges of the slot, according to the present invention. Antenna 1 contains a conductive plate 2 with a slot 3, a feeder 4 with the first 5 and second 6 ends, a radio frequency connector 7, a multi-loop conductor 8. On the conductive plate 2, in general, N holes 9 are made on the first side (in Fig. 1 N=2 ) and M of the holes 10 on the second side (in Fig. 1 M=2) relative to the longitudinal axis of the slot 3, respectively. The outer conductor 11 of feeder 4 has a galvanic contact 12 with the conductive plate 2. The second end 6 of feeder 4 is embedded in a radio frequency connector 7.

A sheet of material such as aluminum, copper, brass, foil-coated getinax and other sheet conductive materials can be used as a conductive plate 2 with a slot 3.

A serial coaxial cable can be used as feeder 4.

Manufacturing the slot antenna 1 according to the present invention is convenient in that the feeder 4 and the multi-loop conductor 8 can be made of the same coaxial cable. In the section from the radio frequency connector 7 to the entrance to the first of the N holes, the cable serves as a feeder. In the area from the entrance to the first of N holes to the end of the multi-loop conductor, the sheath and outer conductor are removed. The central conductor and dielectric, freed from the sheath and outer conductor of the coaxial cable, form a multi-loop conductor that excites the slot antenna.

To form galvanic contact 12 of the outer conductor 11 of the feeder 4 with the conductive plate 2, for example, tin-lead solder can be used. Previously, the surface of the conductive plate 2 is coated with a highly conductive layer, for example, a layer of a tin-bismuth alloy.

As a radio frequency connector 7, a serial radio frequency coaxial connector can be used.

In the conductive plate 2 there is a slot 3, N holes 9, where N≥1, on one side relative to the longitudinal axis of the slot 3 and M, where M≥1, holes 10 on its other side. The outer conductor of the feeder 11 at its first end 5 is galvanically connected to the plate 2 with a slot 3 in the area of the first hole from a set of N holes 9. The central conductor 13 of the feeder with a dielectric is sequentially inserted into the N holes 9, forming N-1 loops, laid over (under) the slot 3, with the formation of a loop, is introduced sequentially into the M holes 10 on the other side relative to the longitudinal axis of the slot 3 with the formation of M-1 loops.

Feeder 4 can be connected to the antenna orthogonally to the surface of board 2, as shown in FIG. 2. This option is convenient when a slot antenna is used with a reflector, i.e. is a one-way slot antenna. The feeder 4 may be located on the surface of the plate 2, as shown in FIG. 3 and fig. 4. This option is convenient when using a double-sided slot in the screen.

Principle of operation

A slot antenna excited by a multi-loop conductor operates as follows. In coaxial cable transmission mode, electromagnetic energy is supplied to a multi-loop conductor. As a result of the flow of electric current through a multi-loop conductor, a magnetic field arises in the immediate vicinity of the conductor, under the influence of which an electric field arises between the long edges of the slot, generating surface electric currents on the surface of the plate. Surface currents are secondary sources of the electromagnetic field in the surrounding space.

By changing the number or geometric dimensions of loops of a multi-loop conductor, it becomes possible to tune a slot antenna to resonance in a wide frequency range.

Example of a slot antenna excited by a multi-loop conductor

The characteristics of a sample slot antenna excited by a multi-loop conductor were simulated, as shown in Fig. 2. A prototype of a slot antenna excited by a three-loop conductor was made.

The prototype of a slot antenna excited by a three-loop conductor contains a plate made of aluminum alloy AMG6 measuring 195 × 110 mm, in the center of which there is a slit 180 × 10 mm. Plate thickness 2 mm. There are four holes on the plate. The centers of the holes are located on a straight line passing through the center of the antenna perpendicular to the longitudinal axis of the slot. The centers of the first holes, lying on opposite sides of the longitudinal axis of the slot, are located at a distance of 20 mm from the axis of the slot. The second holes are spaced 15 mm from the first holes. A coaxial cable with a characteristic impedance of 50 Ohms is connected to one of the second holes (for definiteness, let's call it the right one) orthogonally to the plate. The cable braid is combed and soldered onto the plate using POS 61 solder. The sheath and braid are removed from the part of the coaxial cable outside the second hole on the right side. The center conductor in the dielectric is passed through the first right hole to form a first loop, passed under the slot to form a second loop, passed through the first left hole in the plate, and then passed through the second hole to form a third loop. The height of the loops could be adjusted from 2 mm to 20 mm.

In fig. Figure 6 shows the calculated dependences of VSWR on frequency for six variants of loop heights (configurations). As can be seen from examining the graphs in Fig. 5, by changing the height of the loops, you can shift the matching band of the antenna with the feeder in a wide frequency range.

In fig. Figure 6 presents the results of modeling the matching of a slot antenna with a feeder with traditional excitation of the antenna by a piece of conductor located between the long edges of the slot.

In fig. For comparison, Fig. 7 shows the envelopes of the minima of the dependence of VSWR on frequency. As can be seen from examining the graphs in Fig. 7, the tuning band of a slot antenna excited by a multi-loop conductor is significantly wider than the tuning band of a slot antenna excited by a section of conductor between the long edges of the slot. So, for example, at the VSWR level = 1.15, the tuning ranges differ by 8 times.

Experiments carried out on a mock-up of a slot antenna excited by a multi-loop conductor showed that the tuning range of the antenna with the feeder, as agreed upon at the VSWR level = 1.1, is 400 MHz with an average frequency of the tuning range equal to 1000 MHz. Thus, the tuning bandwidth of a slot antenna excited by a multi-loop conductor is an order of magnitude greater than the tuning bandwidth of a slot antenna excited by a section of conductor located between the long edges of the slot.

Application

A slot antenna excited by a multi-loop conductor can be used as an independent transmitting, receiving or transceiver antenna, as well as being a radiating element of an antenna array, a feeder for aperture antennas, and an exciter for box antennas.

It should be clear that not only a coaxial cable, but also any other electromagnetic energy transmission line containing conductors can serve as the feeder of a slot antenna excited by a multi-loop conductor: a symmetrical strip line, an asymmetric strip line, a microstrip transmission line. A multi-loop conductor can be made of a conductor with other cross-sectional shapes: square, rectangular, elliptical, or a non-canonical cross-section. Any dielectric material can be used as a dielectric: polyethylene, fluoroplastic and others.

Claims (2)

1. A method for exciting a slot antenna with a multi-loop conductor, characterized in that the slot antenna is excited with a multi-loop conductor placed in a plane perpendicular to the plane of the slot. 2. A slot antenna containing a conducting plate with a slot, a coaxial feeder with an outer conductor and a central conductor in a dielectric, characterized in that the conductive plate with a slot has N, where N≥1, holes on one side relative to the longitudinal axis of the slot in a straight line , intersecting with the axis of the slot, M, where M≥1, holes on its other side on the continuation of the mentioned straight line, the outer conductor of the coaxial feeder is galvanically connected to the plate with the slot in the area of one of the holes from a set of N holes, the central conductor of the feeder is located in the dielectric in a plane passing through the said straight line perpendicular to the plane with the slot, inserted sequentially into N holes to form N-1 loops, then laid above or below the slot to form a loop, and then inserted sequentially into M holes to form M-1 loops.