RU2490760C1 - Frequency scanning monopulse antenna - Google Patents

Abstract

FIELD: radio engineering, communication.

SUBSTANCE: antenna consists of two travelling wave power dividers in form of short and long waveguide coils fed from a halver - a hybrid T, coupling windows and a waveguide-slit fabric with alternating-inclined slits on narrow walls of lines, wherein each coupling window on the short coil increases in size successively from the first lower coupling window to the last by 1-2%, and on the long coil all coupling windows remain the same and are equal to the size of the coupling window located in the middle of the short coil; inclination angles of slits also increase from the beginning to the middle of the line from 1° to 20°, and from the middle to the end of the line, inclination angles of slits remain the same, without terminal loads in the coils and lines of the fabric with jumper leads at the ends of the lines, lying at quarter-wavelength distance from the last slits in the lines, made in form of metal plates, while providing the required amplitude distribution.

EFFECT: high antenna efficiency and high accuracy of determining angular coordinates in the scanning plane.

3 dwg

Description

The invention relates to radar systems (radar) tracking with increased accuracy in determining angular coordinates.

Known monopulse antenna, which is a close analogue (prototype) of the claimed device (see. Guide to radar, edited by Meryl I. Skolnik, translated from English by KN Trofimov, Volume 2, Radar antenna devices, Moscow, "Soviet Radio", 1977, p. 287, fig. 16 “a” [1]). The peculiarity of this monopulse antenna is that for the total difference pattern formation with frequency scanning in the traveling wave scheme, two delay lines are used in the form of power dividers on the waveguide snake - short and long. These two power dividers form the desired amplitude distribution (uniform or falling to the edges) common to the entire antenna in the scanning plane through the couplers. Since the last coupler in the short snake is in the middle of the entire antenna, therefore, it should branch out the highest power. The main disadvantage of this technical solution is that the coupler cannot branch more than half of the power that approached it. In this regard, when calculating the load in a short snake up to 25% of the total power is forcedly laid. Consequently, large power losses occur, and as a result of this, a low coefficient of performance (COP).

The problem to which the invention is directed, is to increase the accuracy of determining the angular coordinate in the plane of scanning, to increase the efficiency by eliminating the waste of supplied microwave power in traveling wave antennas in absorbing loads.

The technical result is to increase the antenna efficiency, reliability, improving the accuracy of determining the angular coordinate in the scanning plane.

To achieve the indicated technical results in a monopulse antenna with frequency scanning, consisting of two traveling wave power dividers in the form of waveguide snakes - short and long, powered from a double divider - a double T-bridge, communication windows and from a waveguide-slotted web with variable slanting slots on the narrow walls of the rulers (see [1] p. 286, Fig. 15), each communication window on a short snake is increased in size sequentially from the first lower communication window to the last by 1-2%, and on the long snake all windows communications remain one are equal in size to the size of the communication window located in the middle of the short snake, and the slope angles of the slots increase from the beginning to the middle of the ruler from 1 ° to 20 °, and from the middle to the end of the ruler the slope angles remain the same, without end loads in the snakes and rulers canvases with shorts at the ends of the rulers located at a quarter-wave distance from the last slots made in the form of metal plates, which provides the necessary amplitude distribution. Due to the increase in the size of communication windows and the slope of slots on the rulers, as well as the elimination of loads, the antenna efficiency has been increased to 25%. All calculations were performed using the HFSS Ansoft program.

That is, the presence of connecting segments of the waveguides allows you to send power to the next line, which previously goes into the load of snakes [1], eliminating these loads on the snakes from the antenna. To simplify the design, when calculating the slope of the slots in the rulers, the power equal to 0.1% (30 dB) is laid in the load, and instead of the load, a short circuit is established at a quarter-wave distance from the last slots in the rulers. At the same time, there is practically no damage to the antenna, as a mirror beam (lobe) of 30 dB is small - comparable with the diffraction lobes of the desired amplitude distribution. Due to this, there is a gain in efficiency, complexity and cost, as well as in increasing the reliability of the antenna.

A distinctive feature of the prototype is that in a monopulse antenna with frequency scanning, each communication window on a short snake increases in size sequentially from the first lower communication window to the last by 1-2%, and on a long snake all communication windows remain the same and equal to the size of the window the connection located in the middle of the short snake, and the slope angles increase from the beginning to the middle of the line from 1 ° to 20 °, and from the middle to the end of the line the slope angles remain the same, without end loads to the snake axes and rulers of the canvas with shorts at the ends of the rulers located at a quarter-wave distance from the last slots in the rulers made in the form of metal plates.

The proposed monopulse antenna with frequency scanning is illustrated in detail in the graphic materials in figure 1-3.

Figure 1 schematically shows a monopulse antenna with frequency scanning, front view.

Figure 2 presents a schematic image with the claimed technical solutions that increase the parameters of a monopulse antenna with frequency scanning, front view.

Figure 3 presents the design of the antenna, a top view.

A monopulse antenna with frequency scanning includes a long snake 1, a short snake 2, a double T-bridge 3, which forms the sum and difference radiation patterns (Σ and Δ), connecting segments of waveguides 4 of the same size for snakes 1 and 2, communication windows (couplers ) 5, shorts 6, waveguide-slotted rulers 7, forming a lattice-web, slots 8.

The waveguide-slotted lines 7 forming the lattice-web are at the ends of the short-circuit 6. Each short-circuit 6 is a metal plate covering the waveguide. Short circuits 6 are placed at a quarter-wave distance from the last slots 8 in the rulers, which ensures an increase in efficiency.

The angles of inclination of slots 8 in the horizontal plane in each line 7 of the web increase from the beginning to the middle of the line from 1 ° to 20 °, and from the middle to the end of the line, the angles of inclination of slots 8 remain the same (see Fig. 2), which provides the antenna with the required amplitude distribution, low level of the petals and the required beam width at a given size.

Each communication window 5 on the short snake 2 increases in size sequentially from the first lower communication window 5 to the last by 1-2%, and on the long snake 1 all communication windows 5 remain the same and equal to the size of the communication window located in the middle of short snake 2.

The essence of the work of this invention lies in the fact that the antenna is fed from the double T-bridge 3 from the bottom, communication windows (taps) 5 feed the bottom line 7 of the canvas from a short snake 2 to the middle. There are no connection windows in the lower part of the long snake 1, therefore, the communication windows 5 and the connecting segments of the waveguides 4 start from the middle of the long snake 1, feeding the upper part of the canvas. Unlike the prototype [1], the power that goes into the load earlier is distributed to all the taps with the highest intensity (by changing the size of the communication windows and the slope of the slots on the rulers, and all absorbing loads are excluded from the antenna).

Thus, thanks to new technical solutions, a monopulse antenna with frequency scanning provides high accuracy in determining the angular coordinate in the scanning plane with increased efficiency. And also reduces the complexity, cost and reliability of the antenna.

Claims (1)

Monopulse antenna with frequency scanning, consisting of two traveling wave power dividers in the form of short and long waveguide snakes, powered from a double divider - a double T-bridge, communication windows and from a waveguide-slotted web with variable-inclined slots on narrow ruler walls characterized in that each communication window on a short snake increases in size sequentially from the first lower communication window to the last by 1-2%, and on a long snake all communication windows remain the same and equal to the size of the communication window, located in the middle of the short snake, the slope angles from the beginning to the middle of the ruler also increase from 1 ° to 20 °, and from the middle to the end of the ruler, the slope angles remain the same, which ensures the necessary amplitude distribution without end loads in the snakes and web rulers with shorts at the ends of the rulers located at a quarter-wave distance from the last slots in the rulers made in the form of metal plates.

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