RU2475902C1 - Microstrip antenna - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: invention may be widely used as an independent receiving or transmitting antenna or an element of a phased antenna array, in particular, the antenna may be used as a receiving antenna in equipment of users of space navigation systems (GPS, GLONASS/GPS, etc.). The microstrip antenna includes a radiating plate, a screen arranged underneath, capacitance elements, fixed on the edges of the radiating plate, and a communication pin, which connects the plate with a power supply line, the antenna is equipped with a dielectric substrate, on the upper surface of which there is a radiating plate, made symmetrical relative to its central axis and having along the contour 2n through cuts with slots reaching the plate edge, and capacitance elements are fixed in the above slots and form together with cuts a metamaterial. Cuts arranged on one axis of the radiating plate clockwise or counterclockwise from a communication pin are made with area of S_n+1, which is more than the area S_n of other cuts, the angle of rotation relative to the communication pin makes, accordingly, +(45±5)° (right polarisation) or -(45±5)° (left polarisation), and ratio of areas of cuts is determined on the basis of the following dependence S_n+1/S_n=1.1+0.05.

EFFECT: reduction of microstrip antenna dimensions without reduction in efficiency of its radiation.

6 cl, 7 dwg

Description

The invention relates to radio engineering, in particular to antennas, and can be used to receive radio signals, in particular, as an active receiving antenna in the equipment of users of space navigation systems (GPS, GLONASS / GPS / GALILEO).

Microstrip antennas (MPAs), due to their compactness and manufacturability, are widely used in many communication systems. Recently, there has been an acute problem of their miniaturization. One of the ways to reduce the dimensions of MPA is to use dielectric substrates with a high dielectric constant (more than 10) [B.A. Panchenko, E.I. Nefedov. Microstrip antennas. M.: Radio and communications, 1986, 145 S.].

However, this leads to a decrease in the MPA matching band and, ultimately, to a decrease in the MPA radiation efficiency.

An alternative way to reduce the size of MPA is to use metamaterials in the design of antennas [C. Caloz, T. Itoh. Elektromagnetic Metamaterial: Transmission Line Theory and Microwave Applications. New York: Wiley and IEEE Press, 2005].

Known MPA with metamaterial, consisting of a loop antenna surrounded by metamaterial [US Application No. 20090140946, class. H01Q 1/50; H01Q 15/08; H01Q 7/08; H01Q 9/16, publ. 2009-06-04].

Its disadvantage can be considered relatively large dimensions, since it is a three-dimensional antenna.

Also known is an antenna consisting of a set of printed circuit boards shorted in the center to the earth plane (mushroom structures) [US Application No. 200880258981, class. H01Q 1/24; H01Q 1/38, publ. 2008-10-23].

The disadvantage of this design is the presence of shorting pins connecting the printed circuit boards with the ground plane.

The closest technical solution to the proposed one is a microstrip antenna, including a radiating plate, a screen located below it, capacitive elements mounted on the edges of the radiating plate, and a communication pin connecting the plate to the power line [RF Patent No. 2390890, cl. H01Q 3/00, H01Q 1/38, H01Q 21/24, publ. 05/27/2010].

In the known antenna, the radiating plate and the screen are located opposite and separated from each other, capacitive elements are made on the edges of the radiating plate and the screen in the form of a set of short ribs bent inward between the screen and the radiating plate to reduce the resonant size.

The disadvantage of this antenna is that the plates overlap the radiation region of the microstrip antenna located along the perimeter of the radiating element between its edge and the screen, which, if the resonant size of the radiating plate is sufficiently large, worsens the radiation efficiency.

An object of the invention is to reduce the size of the microstrip antenna without reducing the efficiency of its radiation.

This problem is solved in that the microstrip antenna, including a radiating plate, a screen located beneath it, capacitive elements mounted on the edges of the radiating plate, and a communication pin connecting the plate to the power line are provided with a dielectric substrate, on the upper surface of which there is a radiating plate made symmetrical in shape with respect to its central axis and having 2n through cuts along the contour, where n = 1, 2, 3 ..., with slots extending to the edge of the plate, and capacitive elements are fixed in the above firs and form, together with cutouts metamaterial.

Preferably, the radiating plate was made of any of the known symmetrical shapes, for example round, square, polygonal, and the cutouts of the plate were also made of a symmetric shape, for example, round, diamond, square, polygonal ..

Preferably, the cutouts of the plate perform the same area.

Preferably, the cutouts located on the same axis of the plate clockwise or counterclockwise from the connection pin are made with an area S _{n + 1} larger than the area S _{n of the} remaining notches, while the turning angle relative to the connection pin is + (45 ± 5) ° or - (45 ± 5) °, and the ratio of the area of the cutouts is determined from the dependence S _{n + 1} / S _n = 1.1 ± 0.05.

It is advisable that the antenna has a high-frequency connector connecting the pin to the power line.

Figure 1 presents a General view of the MPA with metamaterial.

Figure 2 - options for the topology of the printed circuit board.

Figure 3 - equivalent circuit MPA with metamaterial.

Figure 4 is a photograph of the proposed antenna.

Figure 5 - standing wave ratio (SWR) of the inputs of the antenna element.

Figure 6 - radiation patterns (MD) of a microstrip antenna at a frequency of 1600 MHz.

Figure 7 - azimuthal dependence of the radiation field for a frequency of 1600 MHz.

The microstrip antenna includes a radiating plate 1, made of a symmetrical shape relative to its central axis and having a contour 2n of through cutouts 2, where n = 1, 2, 3 ..., with slots extending to the edge of the plate 1 and capacitive elements 3, mounted in the above-mentioned slots , and forming together with the cutouts 2 metamaterial (figure 1).

The antenna also contains a dielectric substrate 4, a conductive screen 5 and a communication pin 6 connecting the plate to the power line.

The radiating plate is located on the dielectric substrate 4, under which the screen 5 is mounted.

Possible topologies of the antenna element are presented in figure 2. The radiating plate 1 of the antenna is made of any of the known symmetrical shapes, for example round, square, polygonal.

The power elements are a high-frequency connector (not shown in FIG. 1) and pin 6. Pin 6 is attached to the connector at one end and to the radiating plate 1 at the other end. The place of connecting pin 6 to the plate is selected from the condition for obtaining an input resistance of 50 Ohm at the center frequency of the range. This distance from the center of the plate 1 is about a third of half its size.

The conductive screen 5 serves to create a predominantly unidirectional radiation (reception) of a microstrip antenna.

The cutouts 2 of the plate 1 are made of a symmetrical shape, for example, round, diamond-shaped, square, polygonal, and can have the same area or different.

To ensure radiation of the field of circular polarization, the cutouts 2 in the plate 1 are not the same, and their location relative to the batteries should be strictly fixed.

For a right-polarized field, cutouts 2 located on the same axis clockwise from pin 6 of plate 1 should be slightly larger in area relative to the other cutouts 1, and the rotation angle relative to the feed point should be + (45 ± 5) °.

For a left-polarized field, cutouts 2 located on the same axis counterclockwise from the feed point of the plate 1 should be slightly larger in area relative to the other cutouts 2, and the rotation angle relative to the feed point should be - (45 ± 5) °.

The magnitude of the difference in the area of the enlarged cuts, as well as their exact location within a given range of angles, is determined by the parameters of the dielectric constant of the substrate 4 — its thickness and the value of the dielectric constant. These values are determined numerically. Numerical studies of various configurations of the emitting plate, the characteristic results of which are given in the table for different values of the dielectric constant of the dielectric substrate and its thickness, showed that the ratio of the cut-out areas can be determined from the dependence S _{n + 1} / S _n = 1.1 ± 0.05 .

Table Radiant Plate Shape ε substrate Substrate Height Sn + 1 / Sn square twenty 6 mm 1.05 square 16 6 mm 1,08 octahedron 9.5 3 mm 1.15 round twenty 6 mm 1.05 square 3.6 3 mm 1.15

The principle of operation of a microstrip antenna is well known and consists in the fact that when a high-frequency signal is fed to the antenna input, high-frequency oscillations of a certain type are excited in it, and the radiation is due to the field “protruding” from the edges of the antenna, namely, from the gaps between the radiating plate 1 and screen 5.

In plate 1, excitation of many types of oscillations (modes) is possible, but only the lowest of them forms an axial MD, higher types of oscillations give toroidal MDs with a dip in the axial direction. The lowest types of vibrations for the simplest types of radiating plate 1 are: mode ТМ10 for a rectangular one, mode ТМ11 for a round radiator. To coordinate the plate 1 with the supply pin 6, the connection point (power point) must be combined with the point at which the input impedance is 50 Ohms at the center frequency of the range. In the operating frequency range, the input impedance becomes complex, and the matching range for a given value of the SWR is wider, the thicker the dielectric substrate 4.

In the microstrip antenna under consideration, the radiating plate 1 is made as a composite annular left-handed screw (vectors E, H, k form the left three vectors) of the transmission line formed by concentrated capacitances C ₁ and inductances L _{1 of the} notches of plate 1.

The concentrated capacitances C ₁ and inductances L ₁ form a metamaterial that can be represented as an equivalent CL chain [Fig. 3]. Through the plate 1, the inductors L _{1 are} mounted on the base of the antenna through a large capacitance formed by the plate 1 and the screen 5.

The inclusion of metamaterial around the perimeter of the emitting plate 1 reduces its dimensions without reducing the radiation efficiency.

Based on the above principles, the GLONASS / GPS navigation antenna was calculated and designed (Fig. 4). In the design of the emitting plate 1, MT16 ceramics with ε _g = 16 was used. Its dimensions were 18 mm × 18 mm × 6 mm, and the screen size was 5-19 mm × 19 mm

The experimental characteristics of this antenna are shown in FIGS. 5-7.

From the above data it can be seen that the antenna has a wide beam, which is extremely important for a navigation antenna. The azimuthal dependence of the radiation field in the far zone has a symmetrical shape.

Claims (6)

1. Microstrip antenna, including a radiating plate, a screen located below it, capacitive elements mounted on the edges of the radiating plate, and a communication pin connecting the plate to the power line, characterized in that the antenna is provided with a dielectric substrate, on the upper surface of which a radiating plate is located, made of a symmetrical shape relative to its central axis and having 2n through cuts along the contour, where n = 1, 2, 3 ..., with slots extending to the edge of the plate, and capacitive elements are fixed in the above-mentioned slots x and form, together with cutouts metamaterial. 2. The microstrip antenna according to claim 1, characterized in that the radiating plate is made of any of the known symmetrical shapes, for example round, square, polygonal. 3. The microstrip antenna according to claim 1, characterized in that the cutouts of the plate are made of a symmetrical shape, for example round, diamond-shaped, square, polygonal. 4. The microstrip antenna according to claim 1, characterized in that the cutouts of the plate are made of the same area. 5. The microstrip antenna according to claim 1, characterized in that the cutouts located on the same axis of the plate clockwise or counterclockwise from the communication pin are made with an area S _{n + 1} greater than the area S _{n of the} remaining notches, the angle of rotation relative to the communication pin is respectively + (45 ± 5) ° or - (45 ± 5) °, and the ratio of the area of the cuts is determined from the following dependence S _{n + 1} / S _n = 1.1 ± 0.05. 6. The microstrip antenna according to claim 1, characterized in that the antenna has a high-frequency connector connecting the pin to the power line.

Images