RU2307432C2 - Composite dielectric material and antenna lens made of this material - Google Patents

Abstract

FIELD: antenna engineering.

SUBSTANCE: proposed composite dielectric material used, for instance, to produce antenna lenses of desired dielectric constant and density capable of operating under vibrating load conditions at temperatures ranging between -60 and +85 °C has epoxy resin functioning as binder and hollow glass microspheres and titanium, as fillers, their proportion being given in invention specification.

EFFECT: enhanced resistance to vibrations, enlarged operating temperature range.

2 cl, 1 tbl

Description

The invention relates to radio engineering and can be used in antenna technology.

The development of the technique of lens antennas along with the improvement of their designs, including involves the creation of composite dielectric materials with specified electrophysical and physico-mechanical properties.

In the article “Dielectric Lens Antennas for EHF and Microwave Ranges” (Foreign Radio Electronics No. 4/1990, Moscow, “Radio and Communication”, authors A. Skorodumov, Doctor of Technical Sciences G. Troshin, k. the so-called Kharlanov Yu.Ya., p.93-94) it is indicated that composite dielectrics are mixtures of various materials, changing the ratio and composition of which allows you to achieve the required characteristics, including electrical. Syntactic plastics (syntactic foams) are a fundamentally new type of gas-filled plastics. They consist of a polymer (binder) in which hollow or non-porous microspheres (organic or inorganic) are evenly distributed over the volume. Microspheres, the preferred diameter of which is 20 ... 80 μm, can be made of polymers or ceramics, but glass is most often used (ε _eff = 1.2 ... 1.3; tgδ = (2 ... 8) · 10 ^-4 ). Microspheres have a closed-cell structure, so syntactic foams have a number of advantages over conventional foams: low water absorption, high specific and absolute compressive strength, uniform bulk density, low shrinkage during curing, and increased dimensional stability with increasing temperature. The dielectric properties of syntactic plastics can vary widely, changing the ratio of binder and filler, as well as their composition and manufacturing technology. In addition, the introduction of microspheres into composite dielectrics makes it possible to achieve the required material density.

Known dielectric dielectric lens made of a composite material designed to operate at radio frequencies (H01Q 19/06, US 6489928 B2, published 03.12.2002). The dielectric lens is made of a composite material containing an inorganic dielectric filler and an organic polymer with a dielectric constant of from 1 to 1.05, which have foams. The disadvantage is the possible heterogeneity of the composite material, as a result of which a non-uniform dielectric constant is possible inside the shell made of such a material.

Closest to the proposed invention is a composite dielectric material with improved uniformity (Н01Q 15/08, Н01В 3/44, НВВ 3/00 (11), EP 1126545 A1, published August 22, 2001) containing polystyrene foam and a filler as a binder - titanium dioxide. To improve the adhesion of titanium dioxide to polystyrene foam, the composite dielectric material additionally contains a bonding material, for example wax, polyurethane or epoxy resin, in an amount of 1-25% with respect to the total weight of the composition. Despite the fact that polystyrene foam has the lowest level of heat loss, its disadvantages are low thermal stability (68-70 ° C) and increased combustibility.

The aim of the invention is to obtain a composite dielectric material with high uniformity, operable in the temperature range from -60 to + 85 ° C and under vibration loads, intended, for example, for the manufacture of a spherical dielectric lens.

This goal is achieved by the fact that the composite dielectric material contains epoxy resin as a binder, and glass hollow microspheres and titanium dioxide as fillers in the following ratio of components, wt.%:

Epoxy resin 74.3-82.8 Glass hollow microspheres 5.7-12.5 Titanium dioxide rest

The use of epoxy resin provides manufacturability and wetting ability, high adhesive and cohesive strength, low shrinkage during curing without isolation of by-products, as well as high moisture resistance of the composite dielectric material, the stability of its physicomechanical and dielectric properties and, accordingly, the stability of the radio technical characteristics of the product.

The use of glass hollow microspheres and titanium dioxide provides a composite dielectric material with a given permittivity and density.

Composite dielectric material made from these components has a uniform structure, which ensures repeatability of the manufacture of lenses with desired characteristics.

Four compositions of dielectric compositions were made. The permittivity was measured on samples with a size of 23 ± 0.1 × 10 ± 0.1 × 9.3 mm.

Measurements of ε were carried out on a swivel measuring instrument panoramic Р2-61 at a frequency of 10 ¹⁰ Hz.

The measurement results are shown in table No. 1.

Table number 1 Composition Components Composition, wt.% one 2 3 four Epoxy resin 81.25 82.8 74.3 92.3 Titanium dioxide 6.25 10.3 twenty - Microsphere 12.5 6.9 5.7 7.7 The dielectric constant at a frequency of 10 ¹⁰ Hz 2,53 2.6 3.2-3.3 2.45 Density g / cm ³ 0.896 0.925 1,168 0.987

The introduction of glass hollow microspheres into the epoxy resin lowers its density from 1.16 to 0.987, and the dielectric constant from 4.8 to 2.45 (composition No. 4).

Of the composite dielectric material with the required dielectric constant and density, in particular, lenses were made using the following technology.

Preparation of composite dielectric material:

1. Warm up the epoxy resin ED - 16 to a temperature of (120 ± 10) ° C for 1 h.

2. Dry titanium dioxide on a metal baking sheet with a layer of 2 to 3 cm at a temperature of 110 to 120 ° C for 3.0-3.5 hours and cool at room temperature.

3. Sift through a 0.05 sieve and pour into a tightly closed container made of aluminum, sheet metal or glass. Use dried titanium dioxide for a month. After a month, repeat the drying of titanium dioxide according to claim 2.

4. Dry the microsphere at a temperature of 70 ° C for 2 hours

5. Weigh the components according to the recipe (except PEPA), mix thoroughly for 10-15 minutes.

6. The resulting mixture is heated at a temperature of 80 ° C for 1 h. Then, the mixture is evacuated at a temperature of 65 to 75 ° C and a residual pressure of 5 to 10 mm Hg. until the cessation of active blistering.

Cool the evacuated mixture to a temperature of (25 ± 10) ° С and introduce polyethylene polyamine with uniform stirring.

Vacuum the composite dielectric material at a residual pressure of 5 to 10 mm Hg. not more than 10 minutes, given the viability of the compound.

7. The viability of the prepared composite dielectric material is not more than 40 min depending on the ambient temperature: (25 ± 10) ° С.

8. After preparing the composite dielectric material, fill the product.

Filling lenses made of composite dielectric material:

1. Degrease the form with an alcohol-nephras mixture using a coarse calico swab or brush.

2. Dry at a temperature of 25 ± 10 ° C for at least 30 minutes and coat with SKT grease (synthetic rubber from 5 to 10 parts by weight, toluene from 95 to 90 parts by weight) or Penta - 107. “Penta - 107” should be dried at a temperature of (25 ± 10) ° С for no more than 45 minutes.

3. Keep the mold in air for 15-20 minutes. Apply a second coat of SKT grease. Place a mold coated with a second layer of grease in a thermostat and hold for 2 hours at 180 ° C. Then cool to room temperature.

4. Pour into the mold, after all the air bubbles come out - close the mold.

5. Maintain the mold in air at a temperature of (25 ± 10) ° С for 3 hours, then at a temperature of (60 ± 10) ° С for 6 hours.

6. Remove the product with the mold from the oven and cool.

7. Disassemble the mold, remove the part and remove the flake.

8. Parts made of composite dielectric material must be kept under normal conditions for 24 hours before mechanical or climatic tests, at least.

Further, the lenses are tested for climatic aging according to GOST 9.707-81 “Polymer materials. Accelerated Climate Aging Test Methods. ” The test for the influence of negative temperature, simulating one year of storage of products in any climatic region, was carried out in the following mode:

- exposure at a temperature of -20 ° C - 30 min;

- exposure at a temperature of -60 ° C - 6 hours;

- exposure at a temperature of + 20 ° C - 1 hour.

An imitation of 7 years of storage was carried out.

The test for the effects of temperature differences simulating one year of storage in any climatic region was carried out in the following mode:

- exposure at a temperature of -60 ° C - 2 hours;

- exposure at a temperature of + 85 ° C - 2 hours.

A total of 12 cycles were carried out - an imitation of 12 years of storage.

Test for moisture resistance for 10 days at a temperature of 55 ± 2 ° C and relative humidity of 98-100%.

After testing, the lenses did not change in appearance, there were no cracks, no chips, and the sizes of the lenses did not change geometrically.

With lenses made of composite dielectric material, the antennas were assembled and tested:

1. For cyclic temperature changes from -60 ° C to + 85 ° C with an exposure of 2 hours at each temperature, only 5 cycles.

2. Heat resistance with exposure at a temperature of + 85 ° C for 2 hours, then with exposure at a temperature of 100 ° C - 10 minutes.

3. On moisture resistance at a temperature of + 40 ° C and relative humidity of 98% for 10 days.

4. Mechanical tests of antennas:

a) the effects of random broadband vibration.

Frequency range, Hz Spectral vibration density over the entire range, m ² / s ⁴ Hz (g ² / Hz) RMS total acceleration, m / s ² (g) Time h 20-2000 Over the entire range, linear 147 (15) twenty

Test in three positions with a uniform breakdown of the total time of 20 hours;

b) on the impact of mechanical shocks of a single action.

Peak shock acceleration, m / s ² (g) Duration of impact acceleration, ms The number of strokes in each direction 1470 (150) 2-6 3

Test in three positions;

c) on the impact of repeated mechanical shock.

Peak shock acceleration, m / s ² (g) Duration of impact acceleration, ms Total hits on three axes 740 (75) 5-10 4000

Test in three positions with a uniform breakdown, the total number of strokes - 4000.

5. For cyclic temperature changes from -60 ° C to + 85 ° C with an exposure of 2 hours at each temperature, a total of 5 cycles.

After each type of test, control was made in appearance.

6. After climatic and mechanical tests, the PTX antennas were checked.

Antennas with the claimed composite dielectric material from which the lenses are made correspond to the technical requirements for the product.

Thus, as this is confirmed by the results of experiments and tests, the task was solved and the required technical result was achieved. The use of composite dielectric material, for example, for the manufacture of lenses, made it possible to ensure a given dielectric constant and density, as well as operability under conditions of vibration loads in the temperature range from -60 to + 85 ° C.

Claims (2)

1. Composite dielectric material containing a polymeric binder material - epoxy resin and fillers - titanium dioxide and microspheres, characterized in that it contains glass hollow microspheres and is made with the following ratio of components, wt.%: epoxy resin 74.3-82.8 glass hollow microspheres 5.7-12.5 titanium dioxide Rest 2. Antenna lens, characterized in that it is made of a composite dielectric material according to claim 1.