RU2360338C1 - Broadband three-band horn-microstrip antenna - Google Patents

Abstract

FIELD: radio engineering.

SUBSTANCE: present invention relates to radio engineering, particularly to broadband horn-microstrip antennae of the microwave range, and can be used in metrology, in communication systems, in microwave flaw detection and radio monitoring. The antenna has a horn (H), a resonator with corresponding connections and a ferrite ring (FR). The horn and shunt are in form of a right cylinder with a rectangular cross section. The rear wall of the horn is the reflector-screen, and the resonator plate is placed in parallel to the reflector-screen and is made from metal with the shape of an isosceles triangle. The peak of the isosceles triangle of the MP resonator is joined to the centre conductor of the supply coaxial line (CL). The supply coaxial line is connected to the MP resonator through the smaller lateral wall of the horn perpendicular to it. The outer conductor of the coaxial line is attached to the lateral wall of the horn, and he ferrite ring is attached to the reverse side of the dielectric substrate of the resonator plate such that, its centre is on the axis of symmetry of the isosceles triangle of the MP resonator in the middle between the shunt and the peak of the isosceles triangle.

EFFECT: reduced size and provision for efficient reception and transmission of signals of known standards of cellular and trunk communication systems.

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Description

The invention relates to radio engineering, in particular to broadband (ШП) horn-microstrip antennas of the microwave range, and can be used in metrology, in communication systems, in radio fault detection, radio monitoring, in solving problems of electromagnetic compatibility.

Known "Horn antenna" (see Pat. RU No. 2250542, IPC 7 H01Q 13/02, publ. 04/20/2005, bull. No. 11). It contains a rectangular horn, the end of which is closed by a metal plug, three metal ridges of a special shape and a special connection. The antenna provides reception and transmission of signals in a relatively wide frequency band with a high level of coordination and a linear phase-frequency characteristic. However, it is unsuitable for working with a significant class of NW signals due to insufficient broadband. In addition, the analog is characterized by sufficiently large dimensions, the value of which is determined by the average value of the signal frequency.

The well-known "Disk microstrip antenna" (see ed. St. USSR No. 1573487, IPC 5 H01Q 1/38, publ. 06/23/90, bull. No. 23). It contains a dielectric substrate, on one side of which there is a metal screen, and on the other - a conductive disk in which a slot, a pin probe, a coaxial feeder and a shunt with corresponding connections are made. The antenna provides the formation of an isotropic radiation pattern in the horizontal plane and a decrease in size by 2-4 times in comparison with known samples.

Also known is the "Small Antenna" (see ed. St. USSR No. 1141482, IPC 5 H01Q 13/10, publ. 02.23.1985, bull. No. 7). It contains two metal plates placed parallel to the metal screen, one of them is connected to the screen by means of a shunt, and the second is connected to the supply feeder, and a ferrite ring. The antenna provides increased stability of the shape of the pattern in the working frequency band while reducing dimensions and maintaining the gain.

As the main drawback of these analogs, their insufficient broadband for working with broadband signals of modern communication systems with mobile subscribers should be noted, they are large, especially at frequencies of 450 MHz and lower.

Closest in technical essence to the claimed device is "Ultra-wide compact horn-microstrip antenna with high directivity" (see Pat. RU No. 2289873, IPC 7 H01Q 3/02, publ. 12/20/2006, bull. No. 35) .

The prototype device contains a truncated conical horn, provided with a flat wall on the narrow side of the metal and which is a reflector screen, a resonator formed by a reflector screen and a round metal plate mounted coaxially and symmetrically on the shunt in the center of the inner side of the reflector screen, and the plane of the circular plate of the resonator is parallel to the reflector screen, which ensures reliable mechanical and electrical contact of the round plate with the reflector screen, a tip made of metal and having the shape a truncated cone with a diameter of the base and a height approximately equal to half the distance between the round plate and the reflector screen. The tip tip is connected to the central conductor of the supply coaxial line, and the axis of symmetry of the tip is perpendicular to the plane of the circular resonator plate and passes through its edge. The supply coaxial line is brought to the reflector screen perpendicular to it, and the external line conductor is fixed to it with a reliable electrical contact. The central conductor is connected to the edge of the circular resonator plate by a ferrule with a reliable electrical contact.

The prototype antenna provides reception and transmission of signals in a relatively wide frequency band (at SWR = 2, f _av = 4.5 GHz, ∆F = 0.6 GHz). In addition, it became possible, while maintaining the antenna gain, to reduce its dimensions (to reduce the thickness of the horn by about three times) and reduce the level of the side lobes of the radiation pattern.

The prototype antenna also has a significant drawback. It is unsuitable for working with a significant class of NW signals due to insufficient broadband.

Currently, the urgent task of creating compact directional antennas for receiving and transmitting signals in communication networks with macro and microcellular structures using the following frequency bands: 450-470 MHz, 890-1000 MHz and 1690-2400 MHz (see Ratinsky M. B. Fundamentals of Cellular Communication / Edited by D.V. Zimin. - M.: Radio and Communications, 1998). Even greater complexity is the development of a compact directional ultra-wideband antenna that provides efficient reception and transmission of signals simultaneously in all of these frequency ranges.

The aim of the proposed technical solution is to develop a broadband tri-band compact antenna that provides efficient reception and transmission of signals of known standards of cellular and trunk communication systems.

This goal is achieved by the fact that in the known device, consisting of a horn made of metal, the back wall of which is a reflector screen, a resonator formed by a reflector screen and a metal plate located on a dielectric substrate and mounted coaxially and symmetrically on the shunt in the center of the inner side of the reflector screen, while the plane of the resonator plate is parallel to the reflector screen and reliable mechanical and electrical contact of the plate with the reflector screen is provided, and I feed coaxial line, an additional ferrite ring is introduced, located on the other side of the dielectric substrate of the resonator metal plate, the shunt and horn are in the form of a straight cylinder with a rectangular cross section, and the resonator plate is made in the form of an isosceles triangle, the axis of symmetry of which is perpendicular to two opposite smaller sides of the horn and passes through their axis of symmetry and the point of attachment of the plate with a shunt, and the apex of the isosceles triangle of the metal plate is resonant The aperture is complemented by symmetrically protruding strip elements, the location and dimensions of which are determined by the values of the specified operating frequency bands, the apex of the isosceles triangle of the resonator metal plate is connected to the central conductor of the supply coaxial line by a reliable electrical contact, and the supply coaxial line is connected to the resonator metal plate through the side wall of the horn perpendicular to it, and the external conductor of the line is fixed to the side wall of the speaker with reliable electrical contact, and the ferrite ring is fixed on the dielectric substrate of the resonator plate in such a way that its center is located on the symmetry axis of the isosceles triangle of the resonator metal plate in the middle between the shunt and the top of the isosceles triangle of the resonator metal plate.

The listed new set of essential features due to the fact that a ferrite ring is introduced and the shape of the horn, resonator and shunt is changed allows us to achieve the goal of the invention: to develop an effective broadband tri-band compact antenna.

The technical result is achieved by creating an antenna that combines the positive qualities of two different types of antennas: a microstrip antenna and a speaker with the addition of a ferrite ring. The microstrip antenna emitter is designed in the form of an isosceles triangle with the addition of symmetrically protruding strip elements. The combination of a box-shaped horn in the form of a straight cylinder with a rectangular cross-section (see Zhuk M.S., Molochkov Yu.B. Designing antenna-feeder devices. - M .: Energia, 1966, pp. 509-512)) and a radiator of the named form Together with the shunt and ferrite ring, it is possible to obtain the optimal distribution of the electromagnetic field over the antenna aperture in three frequency sub-bands: 450-470 MHz, 850-1000 MHz and 1500-2100 MHz. When solving this problem, the multiplicity of the considered frequency ranges was taken into account. The proposed antenna design allows, while maintaining the gain, to reduce the overall characteristics of the product in thickness to values

0.07λ ₁ , 0.17λ ₂ and 0.29λ ₃ (where λ ₁ , λ ₂ and λ ₃ are the wavelengths for the middle frequencies of the used sub-bands), which is significantly less than that of the prototype. In addition, the size of the antenna aperture has been significantly reduced (for various frequencies from 2.5 to 10 times compared with the prototype). The proposed antenna design has significantly increased the width of the working frequency range. The width of only the third sub-band of operating frequencies was 600 MHz with an average frequency f _cp.3 = 1.8 GHz (for the prototype 600 MHz at f _cf = 4.5 GHz), which corresponds to the gain of the claimed antenna in broadband even without taking into account the first and second sub-bands in relative units η = ∆f / f _cp 2.5 times.

The inventive antenna is illustrated by drawings, where

figure 1 shows a fully assembled antenna in accordance with the claimed invention;

figure 2 illustrates a triangular resonator plate in a scale of 1: 1;

figure 3 shows the dimensions of the inventive antenna;

figure 4 shows a graph of the measured frequency characteristics of the inventive antenna (the dependence of the SWR from the frequencies used) in the band from 400 MHz to 2.2 GHz;

figure 5 illustrates the dependence of the SWR from the used frequency in the band 450-470 MHz;

figure 6 shows the measured values of the input impedance of the antenna for frequencies 450-470 MHz;

7 illustrates the dependence of the SWR for the frequency band from 800 to 1030 MHz;

on Fig shows the measured values of the input impedance of the antenna for 860-940 MHz;

figure 9 illustrates the measured values of the SWR in the frequency band 1400-2200 MHz;

figure 10 shows the measured values of the input impedance of the antenna for frequencies 1500-2000 MHz;

on figa, b, c shows the distribution of the field E and current I on the proposed resonator plate for frequencies 450-470 MHz, 800-1000 MHz and 1500-2200 MHz, respectively.

Figure 3 presents the optimal dimensions of the antenna, which were obtained on the prototype, tuned to three frequency bands: 450-470 MHz, 850-1000 MHz and 1500-2200 MHz. The antenna aperture area D _A × D _B was 140 × 60 mm. The area of the grounded horn reflector screen is also 140 × 60 mm. The resonator plate is made in the form of an isosceles triangle with a base of 58 mm and a height of D _p = 130 mm with the addition of strip elements (see figure 2). The installation height of the resonator plate above the ground h _p = 37 mm, which is 0.4λ ₃ for the third subband. The latter is selected experimentally to provide a maximum antenna gain of +10 dBi in the third subband. The gain in the first and second sub-bands is 6 dBi and 7 dBi, respectively. The height (or thickness) of the antenna _with h taking into account the wall thickness of the reflector is 40 mm. The diameter of the shunt 3 is 30 mm.

The broadband tri-band horn-microstrip antenna (see FIGS. 1 and 2) comprises a horn 1 made of metal, the back wall of which is a reflector screen, a resonator 2 formed by a reflector screen and a metal plate located on a dielectric substrate 6 and mounted coaxially and symmetrically on a shunt 3 in the center of the inner side of the reflector screen, while the plane of the resonator plate 2 is parallel to the reflector screen of the horn 1 and reliable mechanical and electrical contact is provided, and the supply coax nuyu line 4.

To ensure efficient reception and transmission of signals of known standards of cellular and trunk communication systems, a ferrite ring 5 is additionally introduced, placed on the other side of the dielectric substrate of the metal plate of the resonator 2. The horn 1 and shunt 3 are made in the form of a straight cylinder with a rectangular cross section. The resonator plate 2, in turn, is made in the form of an isosceles triangle. The axis of symmetry of the resonator plate 2 is perpendicular to the two opposite smaller side walls of the horn 1 and passes through their axis of symmetry and the mounting point of the plate with shunt 3. The top of the isosceles triangle of the resonator plate 2 is complemented by symmetrically protruding strip elements 7.1, 7.2, 8.1, 8.2 (see Fig. .2), the location and dimensions of which are determined by the specified values of the operating frequency bands. The top of the isosceles triangle of the resonator plate 2 is connected to the central conductor of the supply coaxial line 4 by a reliable electrical contact, and the supply coaxial line 4 is connected to the horn 1 through a small side wall perpendicular to it. The external conductor of line 4 is fixed to this side wall of the speaker 1 by a reliable electrical contact. The ferrite ring 5 is fixed on the dielectric substrate of the plate of the resonator 2 so that its center is located on the symmetry axis of the isosceles triangle of the metal plate of the resonator 2 in the middle between the shunt 3 and the top of the isosceles triangle of the metal plate of the resonator 2.

Broadband tri-band horn microstrip antenna operates as follows. The inventive antenna (see figures 1, 2 and 3) consists of three main parts: horn 1, resonator 2, which is a slotted antenna of a special shape and fed in a special way directly through the small side wall of the horn 1, shunt 3 and ferrite ring 5 The task of shunt 3 is to compensate the reactive components of the input impedance of the antenna in the first frequency subband, as well as prohibiting (as part of open loops) the spreading of currents I along the corresponding part of the triangular plate of the resonator 2 to ensure the formation of a base the characteristics of the antenna in the frequency bands 450-470 MHz, 850-1000 MHz and 1500-2100 MHz (Eisenberg G.Z. Short-wave antennas - M .: State Publishing House for Communications and Radio, 1962, pp. 677-680). The triangular plate of the resonator 2 contains additional symmetrically protruding rectangular strip inhomogeneities, the location, shape and dimensions of which determine the specified values of the frequency bands and were selected experimentally. The height of the triangular cavity plate 2 is approximately λ _1/4 (f ₁ = 450 MHz).

The electrical signals necessary for transmission are supplied to the inventive antenna via coaxial cable 4. The excitation of the resonator 2 begins on the section of the coaxial line 4 between points 10 and 11 (see figure 3). The need for a tip used in the prototype device, has disappeared due to the small length of the Central conductor of the coaxial line 4 in the area 10-11.

The excited electromagnetic wave between the resonator plate 2 and the grounded shield-reflector of the horn 1 forms a distribution of electric and magnetic fields similar to the prototype device on the aperture of the claimed antenna.

Let us consider in more detail the operation of the antenna in the claimed frequency subbands. In the frequency band 450-470 MHz in the maximum amount of play of the antenna 2. The shunt resonator 3 is disposed at a distance of approximately λ _1/8 of powering point and the center of the ferrite ring 5 - removing approximately λ _1/16. As a result, the shunt does not prevent (in conjunction with strip elements) the current I from spreading over the entire surface of the resonator plate 2. The approximate values in the above and the following relations are due to the shortening of the wavelength in the antenna parts, the influence of the dielectric and the horn body. For all two pairs of strip elements 7.1 and 7.2, 8.1 and 8.2 (see FIGS. 2, 4, 5, 6, and 11a) symmetrically protruding from the triangular plate of the resonator (see Figs. 2, 4, 5, 6, and 11a), mutually compensating each other. The characteristics of the antenna under consideration with a triangular resonator plate and central excitation, as well as the physical processes taking place in it, are close in nature to the corresponding characteristics and processes in shunt vibrators above the screen (see Ultra-wideband antennas. Transl. From English S.V. Popova, V.A. Zhuravleva - M .: Mir, 1964, pp. 394-402). The latter include the value of the standing wave coefficient (SWR) in combination with the bandwidth of the working frequency range, the distribution of currents on the resonator plate, and the structure of the emitted field. The measurement results shown in FIGS. 5 and 6 indicate that in the first subband of the claimed frequencies 450-470 MHz, the SWR in the middle is 3. The input impedance in the main part of the subband has a resonant character. The characteristics of the antenna in this subband are adjusted by changing the width of the slit above the base of the isosceles triangle of the resonator plate 2, as well as by varying the size and location of the protrusions 9.1 and 9.2 at its base. On figa illustrates the distribution of the field E and current 7 on a triangular plate of the resonator.

The 890-1000 MHz frequency band the antenna is involved truncated to the level 3 of the shunt resonator 2. Open stub 7.1-7.2 (included approximately 0,18λ _cp2 from the feed point and having a length close to λ _CP2 / 4) prevents spreading currents I along the plate of the resonator 2 during the transition to the second subband with an average frequency f _cp2 .

At the same time, the section from the power point to the loop 7.1-7.2 inclusive can be considered as an asymmetric vibrator with an upper load and a resonant frequency corresponding to the frequencies of the second subband.

The principle of operation of the antenna in this subband is similar to that discussed above. 7 and 8 show the results of measurements of the dependence of the SWR and the input impedance of the antenna from the used frequency band. The latter indicates that in the second sub-frequency range of 890-1000 MHz the SWR is on average 3.5, and the input impedance of the antenna fits in a circle equal to the KBW 0.25. On figb illustrates the distribution of the field E and current I on a truncated plate of the resonator 2. The tuning of the characteristics of the antenna in the second subband is carried out by varying the sizes of the pair of strip elements 7.1-7.2 symmetrically protruding from the triangular resonator. The length of the strip elements 8.1-8.2 determines the average frequency value of the second subband, and their thickness determines the frequency band of the second subband. It should be noted that it is possible to increase the length and thickness of the strip elements 7.1-7.2 and 8.1-8.2 only within certain limits due to the mutual influence of the latter on the characteristics of the antenna realized with their help.

The principle of operation of the antenna in the third subband 1500-2100 MHz is basically similar to its operation in the first two subbands (see Fig. 11c). Working in a predetermined frequency band is achieved by using the lower part of the resonator 2. The play of the vertex of the triangular plates supplemented with 8.1-8.2 strap members located above the screen (horn rear wall) at a distance of approximately λ _3/4.

In the third sub-band of the claimed antenna, a bandwidth of 600 MHz is implemented. The value of the relative bandwidth

Δf '= f ₃ / f _sr3 is 0.3, which entails the multi-resonance nature of its characteristics. To smooth the frequency characteristics, a ferrite ring is used 5. It is located in the region of the highest current density I excited by an electromagnetic field with frequencies of the third subband (in the middle between shunt 3 and the apex of the isosceles triangle of the resonator plate). At the same time, the ferrite ring 5 does not significantly affect the distribution of currents of the second and third sub-frequency bands.

The inclusion of a ferrite ring of grade 10SCh makes it possible to smooth the characteristic of the input resistance and achieve agreement in the entire considered frequency sub-range. The use of ferrite does not lead to a noticeable deterioration in the efficiency of the antenna. In the third subband, the reduction in efficiency is 2-3% and does not have a noticeable effect on its operation in the second and first subranges.

Figures 9 and 10 show the results of measuring the dependence of the SWR and the input impedance of the antenna on the used frequency band 1500-2000 MHz. The latter indicate that the SWR in the considered frequency band is 2, and the input impedance of the antenna fits into a circle equal to the KBM 0.5 and has a multi-resonance character in the region of 50 Ohms. On figv illustrates the distribution of the field E and current I on a truncated plate of the resonator 2. The tuning of the characteristics of the antenna in the third subband is carried out by moving the ferrite ring 5. With it, a change is achieved (within small limits) the average frequency f _cf3 and the boundaries of the third subband frequencies.

The proposed embodiment of the resonator plate 2 was obtained experimentally by varying the sizes of strip elements 7.1-7.2 and 8.1-8.2, a ferrite ring 5.

The inventive antenna can be used as part of a phased array antenna to measure the spatial parameters of the signals in these frequency ranges.

All parts of the antenna according to the present invention have a simple shape and are made of a uniform and uniform conductive material. This makes it possible to realize their manufacture in mass production easily and cheaply, using a pressing or plastic molding followed by a conductive coating.

Claims (1)

Broadband tri-band horn-microstrip antenna, consisting of a horn made of metal, the back wall of which is a reflector screen, a resonator formed by a reflector screen and a metal plate located on a dielectric substrate and mounted coaxially and symmetrically on the shunt in the center of the inner side of the screen -reflector, while the plane of the metal plate of the resonator is parallel to the screen-reflector and reliable mechanical and electrical contact of the plate with the screen -reflector, and a supply coaxial line, characterized in that an additional ferrite ring is placed on the other side of the dielectric substrate of the resonator metal plate, the shunt and horn are in the form of a straight cylinder with a rectangular cross section, and the resonator metal plate is made in the form of an isosceles triangle, the axis of symmetry which is perpendicular to the two opposite smaller side walls of the horn and passes through their axis of symmetry and the point of attachment of the plate with a shunt, and the vertex is equal the shed triangle of the metal plate of the resonator is supplemented by symmetrically protruding strip elements, the location and dimensions of which are determined by the values of the specified operating frequency bands, the top of the isosceles triangle of the plate of the resonator is connected to the central conductor of the supply coaxial line by a reliable electrical contact, and the supply coaxial line is connected to the metal plate of the resonator through the side wall the horn is perpendicular to it, and the external conductor of the line is fixed to b the horn wall of the horn with a reliable electrical contact, and the ferrite ring is mounted on the dielectric substrate of the resonator plate so that its center is located on the symmetry axis of the isosceles triangle of the resonator metal plate in the middle between the shunt and the top of the isosceles triangle of the resonator metal plate.

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