RU2246156C1 - Slotted waveguide antenna array - Google Patents

Abstract

FIELD: microwave engineering; slotted waveguide antenna arrays for radar systems of flying vehicles.

SUBSTANCE: proposed low-silhouette slotted waveguide antenna array enabling use of group method for manufacturing its components is, essentially, multilayer waveguide system that has radiating antenna array divided into a number of subarrays and power distribution circuit. Radiating elements of slotted waveguide antenna array are longitudinal slots in wide walls of waveguides. Multilayer waveguide system is, essentially, multilayer structure assembled of alternating interconnected thin conducting plates and conducting bases, the latter being provided with through holes forming waveguide channels, and plates forming wide walls of waveguides are provided with through holes of radiating or coupling elements, or power supply elements.

EFFECT: facilitated manufacture, enhanced manufacturing and assembling precision, strength, and yield.

8 cl, 10 dwg

Description

The invention relates to techniques for microwave frequencies, namely, waveguide-slot antenna arrays (VCHAR) used in radar systems (radar) of aircraft.

Based on the requirements for radars installed on aircraft, the requirements are determined for the VShAR used in them, which should have minimum weight and dimensions, have high mechanical strength, work stably at high and low temperatures, when exposed to mechanical shocks and vibrations, withstand significant overloads. VCHAR allow you to implement optimal radiation patterns, the band of their operating frequencies can be expanded, and new functionality can be realized by dividing the antenna array (AR) into sublattices. VCHAR have relatively simple exciting devices and are easy to operate.

Known transmitting a waveguide-slot antenna array [1], consisting of parallel located waveguides with radiating slots and located perpendicular to them the exciting waveguide with inclined slots in their common wide wall for communication with radiating waveguides. An exciting waveguide terminates in a flange for connecting an energy source.

The antenna contains a plate with grooves (grooves) formed on it from two opposite sides, on one side of which boxes with radiating slots are inserted and then soldered into these grooves, which are part of the waveguides and form waveguides together with the plate, and on the other hand, a box part of the exciting waveguide. In the plate for communication of the exciting waveguide with the radiating waveguides, inclined slots are cut. The disadvantage of this design is the large thickness of the plate, which is caused by the need to create grooves on its two sides, as well as the inability to create an antenna array of a more complex structure, which allows to expand its functionality.

Closest to the proposed invention, a waveguide-slot antenna array [2], designed to operate in a single-pulse mode and containing two structurally separated nodes: a radiating antenna array and a waveguide power distribution circuit (monopulse comparator). The radiating antenna array is divided into four sublattices located in the quadrants of the circle. The radiating elements of each sublattice are longitudinal radiating slits cut in the wide walls of parallel emitting rectangular waveguides that form the first level of the VCHAR. These waveguides are excited by waveguides located perpendicular to them at the second level of the VCHAR with inclined slots in their common wide walls. The excitation waveguide of each sublattice is connected through a coupling gap to a leading waveguide located at the third level of the VCHAR, which is connected through a common flange to a power distribution circuit designed to form a combined radiation pattern and two difference (in azimuth and elevation) and having three corresponding outputs. The radiating antenna array contains a main body made of aluminum sheet by milling on both sides using a conductor, side parts made by milling, a plate with radiating slots and waveguide covers made of aluminum plate with a thickness of 0.4 and 0.5 mm and coated with the necessary solder . Details of the antenna array are connected by soldering in the melt. The power distribution scheme is made using milling technology on a numerically controlled machine and, like a radiating antenna array, is soldered in the melt and is a separate unit.

The disadvantage of this design of a slotted waveguide antenna is its low-tech nature, since the technology used provides for the application of metalworking methods for each part separately, which does not give good repeatability of dimensions, and hence the parameters of the antenna array, the presence of many small parts entails the use of a large amount of mechanical assembly work. In addition, the disadvantages of this design include the difficulty of implementing a low-profile AR (small thickness), which is caused, firstly, by the relatively large thickness of the aluminum plate with radiating slots, housing walls with inclined slots and waveguide covers due to the use of milling technology and the need to ensure sufficient mechanical rigidity of the aluminum structure and, secondly, due to the presence of two structurally separated units in the VCHAR, which leads to intermediate assembly and, consequently, to an increase in mass and thickness VSCHAR ins.

The objective of the invention is to provide a technologically advanced low-profile design of a slot-waveguide antenna array, which allows to obtain electrical parameters close to theoretically possible with good repeatability, while the proposed design should provide simplicity and accuracy of manufacturing and assembling of VCHAR, the possibility of group methods of manufacturing parts, high strength characteristics products and a high percentage of suitable products in industrial production.

The proposed waveguide-slot antenna array is made in the form of a multi-level system of waveguides and contains a waveguide power distribution circuit and a radiating antenna array divided into several sublattices, the radiating elements of which are made in the form of longitudinal slots in wide walls of parallel located rectangular radiating waveguides that form the first level of the waveguide slot antenna array, perpendicular to which at the second level of the waveguide-slot antenna array are located one for each sublattice exciting waveguides, each of which is electromagnetically coupled to radiating waveguides through communication elements in the form of inclined slots in their common wide walls and is electromagnetically connected to a sublattice supply waveguide located on the third level through a communication element in a common wide wall of these waveguides, while all sublattice waveguides are connected to a power distribution circuit, a multi-level system of waveguides forming a radiating antenna array and a waveguide power distribution circuit In fact, it is made in the form of a multilayer structure of alternating conductive thin plates and conductive bases connected to each other, and through holes are made in each base, forming channels of waveguides of the corresponding level of the slot-wave antenna array, and in adjacent thin plates forming wide walls of these of the waveguides, through holes are made, forming at the corresponding levels of the slot-guided antenna array either radiating elements or holes of the communication elements between the wave by novods of different levels, or openings for supplying energy to a waveguide-slot antenna array.

The coupling element of the exciting sublattice waveguide with the leading waveguide located at the third level is made either in the form of a gap in the common wide wall of these waveguides, or in the form of a round hole in their common wide wall and a pin passing through it, connecting the second opposite wide walls of these waveguides.

Conductive plates and bases are interconnected by soldering.

The conductive plates and bases are made of low carbon steel, while thin layers of conductive materials can be deposited on the surface of the conductive plates and bases, which serve as high-temperature solder when brazing the antenna array.

At least one through hole for controlling the degree of melting of the solder located in the central region of this plate is made in a conductive plate with radiating elements.

Through holes in the conductive plates and bases are made for pins fixing the exact relative position of the plates and bases during assembly.

The proposed multilayer construction of a waveguide-slot antenna array allows one to produce its parts by the group method, for example: plates - by the method of double-sided photolithography, bases - by the method of electric discharge machining of metals. The use of these technologies makes it possible to produce plates of thin steel tape (0.15-0.2 mm thick), and the bases, which are a flat part with through holes (2-3 mm thick), in a package of several pieces. Appropriate coatings are applied to the VChAR parts, which are selected in such a way that, when heated during the brazing process, they form the necessary solder. Soldering the waveguide-slot antenna array as a whole allows you to create a high-strength device with good weight and size characteristics, and the coatings applied to the parts provide high quality factor of the waveguide systems and good protection of the antenna from external factors.

Figure 1 presents a General view (top and bottom) of the slot-wave antenna array.

On figa and figb schematically presents a top and bottom view of the structure of the radiating antenna array, divided into sublattices.

Figure 3 shows parallel to the exciting and supplying waveguides VCHAR with a communication element made in the form of a slit.

Figure 4 shows the perpendicularly located exciting and supplying waveguides VCHAR with a communication element made in the form of a slit.

Figure 5 shows the excitation and supply waveguides of the VCHAR located at an arbitrary angle with a communication element made in the form of a hole and a pin.

Figure 6 shows the details of the waveguide-slot antenna array (thin plates and bases) in the order of their location in the finished VCHAR.

In Fig.7 shows a fragment of the plate and the base of the first level VCHAR with a hole for controlling the degree of solder melting.

Figure 1 presents a General view of one of the embodiments of the proposed waveguide-slot antenna array, which contains a radiating antenna array 1, schematically shown in figa and fig.2b. The radiating AR is divided into four sublattices 2, 3, 4, and 5. In parallel emitting waveguides 6, longitudinal slots 7 are cut, which play the role of radiating elements of the sublattices. A perpendicular to the emitting waveguides in each sublattice at the second level is an exciting waveguide 8. In the common walls of the emitting and exciting waveguide, communication elements are made in the form of inclined slots 9. The exciting waveguides of each sublattice are connected through communication elements to the corresponding input waveguides 10 located at the third level of the VCHAR. The communication elements can be made in the form of a slit 11, as shown in Figs. 3 and 4, while the supply waveguide can be located both parallel (Fig. 3) and perpendicularly (Fig. 4) to the exciting one, and in the case of a perpendicular arrangement of waveguides In the supply waveguide, an exciting pin can be installed located near the slit parallel to the narrow wall of the waveguide. The communication element between the waveguides 8 and 10 can also be made in the form of a hole 12 in the common wide wall of these waveguides and a pin 13 passing through this hole and connecting the second wide walls of the waveguides, as shown in Fig.5. This embodiment of the coupling element has the advantage that the coupled waveguides can be positioned at any angle. Thickening in the form of washers can be made on the pin near the wide walls connected by it to improve matching.

The supply waveguides 10 are connected to a power distribution circuit, which in the proposed design variant of the VCHAR is a monopulse comparator - a sum-difference circuit forming a total and two difference, in azimuth and elevation, radiation patterns. The total-difference scheme is built on four flat double tees.

Figure 6 shows the main details of VCHAR in the order of their location in the finished VCHAR: 14-18 - thin conductive plates in which longitudinal radiating slots 7 are made, inclined communication slots 9 of radiating and exciting waveguides, holes of communication elements 12, and can also be other holes are made if necessary; 19-22 - conductive bases in which through holes 23-26 are made, forming channels of waveguides of the corresponding level, namely: 23 - holes in base 19, forming channels of radiating waveguides, 24 - holes in base 20, forming channels of exciting waveguides, 25 and 26 - holes in the bases 21 and 22, forming the waveguide channels of the input waveguides and power distribution schemes. The plates 16, 17, 18 and the bases 21, 22 form a power distribution scheme between the sublattices of the radiating antenna array formed by the plates 14, 15, 16 and the bases 19, 20. The flanges 27 and 28 of the total and two differential output channels are designed to supply energy to the VCHAR , the holes in the flanges are aligned with the holes for supplying energy to the VCHAR in the plates 17 and 18. In addition, coaxial energy input can be provided in the slot-wave antenna array, as shown in the proposed VCHAR embodiment, for which the sleeve 29 serves, and a hole is provided in the plate 18. The holes 30 and 31 in the antenna parts are designed for pins that serve to align these parts during assembly and fix them during the soldering process. Holes 30 are used to assemble parts that are part of the radiating antenna array, holes 31 are used to assemble parts included in the power distribution circuit. Between themselves, the combination and fixation of two nodes of the antenna is carried out using the holes in the base 20, in which two pairs of pin holes are made, two holes for each of the nodes. VCHAR in other embodiments can be assembled entirely on two pins.

Galvanic coatings were applied to all the details of the VCHAR, M6Ср18 (6 μm copper and 18 μm silver) on the bases, and Н6Ср3 (6 μm nickel as a sublayer and 3 μm silver) on the plates. The composition of the coating applied to the base is close to the eutectic composition of the copper-silver alloy. Due to this coating, the soldering of VCHAR is carried out. The quality of the solder, more precisely, the quality of the solder joints of all necessary surfaces, significantly affects the parameters of VCHAR. To ensure reliable contact of the brazed parts, VSCHAR is assembled in specially designed equipment for soldering. Soldering is carried out in a hydrogen furnace at a temperature of about 800 ° C, which ensures the melting of the solder formed by coating applied to the base. To control the heating of the node, which occurs from the periphery to the center, and determine the reliability of the soldered joints in the center of the plate 14 with radiating slots, a through hole 32 is made (Fig. 7). A groove is formed in the center of the collected VCHAR (the base 19 is the bottom of the groove), which is filled with molten solder during soldering. VCHAR heating stops when the solder spreads well.

Soldering of VSCHAR with copper-silver solder formed due to coating of parts provides high strength of soldered joints, low losses in VCHAR, as well as its protection against corrosion. The technological yield of the VCHAR of the described design is more than 90%.

In the reception mode, the VCHAR receives the incident wave through it emitting longitudinal slots 7, the location of which in the wide walls of the emitting waveguides 6 is determined by the required amplitude distribution. The received signal from the emitting waveguides 6 through the inclined slots 9 is transmitted to the exciting waveguides 8 and then through the communication elements shown in Fig. 5 to the input waveguides 10 of the four sublattices. The signals from the input waveguides are fed to the total-difference scheme, which generates three radiation patterns: the total and two difference, in azimuth and elevation, and accordingly has three outputs for supplying energy, located on two flanges, total 27 and double differential 28.

In transmission mode, the signal is fed to the total input of the VCHAR on the flange 27, is divided into four equal parts by a power distribution circuit, and fed through the supply waveguides 10 of the sublattices to the exciting waveguides 8, of which through the inclined slots 9, into the emitting waveguides 6 and then radiated into free space through the radiating slots 7. The slope of the slots 9 is determined by the magnitude of the signal power, which according to a given amplitude distribution must be transmitted to the radiating waveguides.

In the general case, depending on the magnitude, functional purpose of the VCHAR and the required electrical parameters, the radiating antenna array can be divided into a significantly larger number of sublattices, while the power distribution scheme between the sublattices becomes more complex and can be located at several levels of the VLAR, the number of which is determined complexity of the circuit. Nevertheless, it can be constructed according to the principles proposed in this invention using the described technological methods.

Sources of information:

1. US patent No. 4005431, declared. 05/30/75, No. 582085, publ. 06/25/77. MKI N 01 Q 13/10, NKI 343/771, 767, 770.

2. Harvey P. Muhs, "mm - Wave Antenna," Microwave Journal, pp. 191-194, vol. 28, No. 7, 1985.

Claims (8)

1. The waveguide-slot antenna array, made in the form of a multi-level system of waveguides and containing a waveguide power distribution circuit and a radiating antenna array, divided into several sublattices, the radiating elements of which are made as through holes in the wide walls of parallel located rectangular radiating waveguides that form the first level waveguide-slot antenna array, perpendicular to which at the second level of the waveguide-slot antenna array are located one for each lattices to the exciting waveguide, each of which is electromagnetically connected to the radiating waveguides through communication elements in the form of through holes in their common wide walls and is electromagnetically connected to the sublattice supply waveguide located on the third level through communication elements in the form of through holes in the common wide wall of these waveguides, at this all the supply waveguides of the sublattices are connected to the waveguide power distribution circuit, characterized in that the multilevel system of waveguides forming a radiating antenna This array and the waveguide power distribution circuit is made in the form of a multilayer structure of interconnected alternating conductive thin plates and conductive bases, with through holes made in each base, forming channels of waveguides of the corresponding level of the slot-wave antenna array, and in adjacent thin the plates forming the wide walls of these waveguides are made through holes, forming at the appropriate levels of the slot-wave antenna array or radiating elements or hole coupling elements between the waveguides of different levels, or for supplying energy holes. 2. The slotted waveguide antenna array according to claim 1, characterized in that the radiating elements are made in the form of longitudinal slots, the communication elements between the radiating and exciting waveguides are made in the form of inclined slots, and the coupling element of the exciting sublattice waveguide with a leading waveguide located at the third level made either in the form of a gap in the common wide wall of these waveguides, or in the form of a round hole in their common wide wall and a pin passing through it, connecting the second opposite wide walls of these waves waters. 3. The waveguide-slot antenna array according to claim 1 or 2, characterized in that the conductive plates and bases are interconnected by soldering. 4. The waveguide-slot antenna array according to any one of claims 1 to 3, characterized in that the conductive plates and bases are made of low carbon steel. 5. The waveguide-slot antenna array according to claim 4, characterized in that thin layers of conductive materials are deposited on the surface of the conductive plates and bases. 6. The waveguide slot antenna array according to claim 5, characterized in that the layers of conductive materials perform the function of high-temperature solder when soldering the antenna array. 7. The waveguide-slot antenna array according to claim 3 or 6, characterized in that at least one through hole for controlling the degree of solder melting located in the central region of this plate is made in a conductive plate with radiating elements. 8. The waveguide-slot antenna array according to any one of claims 1 to 7, characterized in that through holes for pins are made in the conductive plates and bases, fixing the exact relative position of the plates and bases during assembly.

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