US2840811A - Dielectric bodies for transmission of electromagnetic waves - Google Patents

Dielectric bodies for transmission of electromagnetic waves Download PDF

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Publication number
US2840811A
US2840811A US43038854A US2840811A US 2840811 A US2840811 A US 2840811A US 43038854 A US43038854 A US 43038854A US 2840811 A US2840811 A US 2840811A
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dielectric
electromagnetic waves
walls
body
transmission
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Edward B Mcmillan
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Edward B Mcmillan
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q15/00Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
    • H01Q15/02Refracting or diffracting devices, e.g. lens, prism
    • H01Q15/08Refracting or diffracting devices, e.g. lens, prism formed of solid dielectric material
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T156/00Adhesive bonding and miscellaneous chemical manufacture
    • Y10T156/10Methods of surface bonding and/or assembly therefor
    • Y10T156/1002Methods of surface bonding and/or assembly therefor with permanent bending or reshaping or surface deformation of self sustaining lamina
    • Y10T156/1003Methods of surface bonding and/or assembly therefor with permanent bending or reshaping or surface deformation of self sustaining lamina by separating laminae between spaced secured areas [e.g., honeycomb expanding]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00Stock material or miscellaneous articles
    • Y10T428/24Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24149Honeycomb-like
    • Y10T428/24165Hexagonally shaped cavities

Description

SEARCH ROOM CROEI REFERENCE June 24, 1958 E E. B. MOMILLAN 2,840,811

DIELECTRIC BODIES FOR TRANSMISSION OF ELECTRQMAGNETIC WAVES Fxled May 1''! 1954 2 Sheets-Sheet 1 I" "W" mull will m WWII vFIGJA FIG. 2

June 24, 1958 5, cMlLLAN -2,840,811

DIELECTRIC BODI FOR ANSMISSION 0F ELECTROMAGNET WAVES Filed May 17, 1954 2 Sheets-Sheet 2 INVENTOR.

- becomes uneven.

United States Patent DIELECTRIC BODIES FOR TRANSMISSION OF ELECTROMAGNETIC WAVES Edward B. McMillan, Ipswich, Mass.

Application May 17, 1954, Serial No. 430,388

4 Claims. (Cl. 343-18) This invention relates to dielectric bodies for transmission of electromagnetic waves and particularly to a new type of dielectric body which may provide both high strength and light weight.

Dielectric walls for transmission of electromagnetic waves have in general been in the form of dielectric sheets or laminates selected as to material and formed as to shape to provide transmission of electromagnetic waves with minimum or controlled distortion. Such bodies have been too heavy or too weak for certain uses. Efforts to provide a light weight dielectric sheet have produced a foamed resin sheet carrying metallic particles dispersed through it. Such dielectric sheets have often been unsatisfactory where great precision is required because of inherent difliculty in securing and maintaining an even distribution of metallic particles during the process of expanding the resin. That is, portions of the resin expand more than others or in a different manner so that the distribution of metallic particles carried by the resin Additionally, the dielectric constants of sheets may vary and there is no available means for adjusting the dielectric constant of the foamed sheet to bring it to a desired value.

It is an object of the present invention to provide a new dielectric body providing a high degree of uniformity and capable of being adjusted to a predetermined dielectric constant.

It is a further object to provide a new dielectric body having a high strength in combination with light weight.

According to the present invention there is created a dielectric body operating as a continuous dielectric in which .a dielectric effect comparable to that of a continuous dielectric wall is secured through the provision of a multitude of regularly positioned walls disposed at a high angle to a wave receiving surface of the body. The dielectric walls carry metallic particles substantially uniformly distributed in electrically insulated relation and provide a very high dielectric constant along the walls in the direction of propagation of the waves.

Figure 1a is an orthogonal view of the edge of a dielectric body constructed in accordance with the present invention;

Figure 1b is an orthogonal view of the face of the dielectric body of Figure la;

Figure 2 is an isometric view of another dielectric body constructed in accordance with my invention;

Figure 3 is an isometric view of the dielectric body of Figures la and 1b abutting a solid dielectric slab;

Figure 4 is an isometric view with a cut-away section showing the dielectric body of Figures la and 1b sandwiched between two dielectric walls.

Example 1 In Figures 1a and 1b is illustrated a dielectric body constructed in accordance with the present invention. A regular cellular supporting structure composed of repeating cells, such as 12 and 14, of substantially uniform size and configuration and of dielectric material provides Patented June 24, 1958 walls typified by 16 and 18 defining hexagonal prisms normal to the wave receiving faces 20 and 22. The cells, such as 12 and 14, have an area taken in a plane parallel to the wave receiving faces 20 and 22 of a size less than cut-off for the electromagnetic waves to be transmitted. Thus wave guide action is avoided. A high dielectric constant along the walls of cells, such as 12 and 14, is provided by metallic particles which the walls support substantially uniformly distributed in electrically insulated relation in sufficient concentration for the purpose. Since cells, such as 12 and 14, are disposed at a high angle away from the wave receiving faces 20 and 22, the dielectric body artifically possesses electrically uniform behaviour in depth. Since it is easy to control the distribution of metallic particles on such faces, a high degree of uniformity can be maintained in securing a predetermined dielectric constant. While the body simulates a solid continuous homogeneous dielectric, its weight can be much less as the cells may be filled with a lighter material or even air. In addition, as the cellular supporting dielectric structure 10 may be very strong, a combination of high strength and low weight can be obtained. Since the dielectric body of Figures la and 1b simulates a continuous dielectric, it may be employed in mixed dielectric constructions to blend with reduced electrical discontinuity With solid dielectric pieces placed against its surfaces and edges.

The cells, such as 12 and 14, defined prisms whose depth was 0.270 inch and whose cross-sections parallel to the Wave receiving faces were equilateral hexagons having a width of 0.144 inch on each side. The walls, typified by 16 and 18, were 0.015 inch thick and comprised a strip of fiber glass fabric rigidified by a cured phenolic resin and covered on both sides with a 0.0045 inch thick cured coating of the following mixture:

Polyester-styrene resin weight parts Benzoyl peroxide catalyst 4.5 weight parts Extra fine aluminum lining powder 25 weight parts The concentration of uniformly distributed electrically insulated metallic particles in this coating imparted to the walls typified by 16 and 18 a sulficiently high dielectric constant so that the measured dielectric constant of the dielectric body in its entirety was 5.32 at 5000 me. It possessed the following mechanical strength properties normal to its wave receiving faces 20 and 22:

Ultimate compressive strength, p. s. i. 609 Ultimate shear strength, p. s. i. 445 Ultimate shear modulus, p. s. i. 21,800 Tensile strength, p. s. i. 488

Its density was only 7.75 pounds per cubic foot.

Example 2 In Figure 2 is illustrated another dielectric body constructed in accordance with the present invention. A regular cellular supporting structure 24 composed of repeating cells, such as 26 and 28, of uniformly varying size and configuration and of dielectric material provided walls typified by 30 and 32 defining rectangular prisms normal to the wave receiving faces 34 and 36. The cells, such as 26 and 28, had an area taken in a plane parallel to the wave receiving faces 34 and 36 of a size less than cut-off for the electromagnetic waves to be transmitted. Thus wave guide action did not take place. The cell walls 30 and 32 were constructed with the material of the cell walls 16 and 18 of Figures la and 1b and coated in the same way with a concentration of uniformly distributed electrically insulated metallic particles, but were filled with polyethylene. In the cellular supporting structure 24 comprising adjacent columns such as 38, 40 and 42 of successively smaller prisms, the

dielectric constant of the dielectric body was increased in the direction in which the cell size was decreased. Thus this dielectric body of uniform thickness effectively simulated a dielectric wedge capable of shifting the path of propagation of microwaves toward the direction of decreasing cell size.

Example 3 In Figure 3 is illustrated in isometric view the dielectric body 44 of Figures 1a and lb abutting a solid dielectric slab 46 having the same dielectric constant and thickness. In the prior art a dielectric Wall comprising a low density body contiguous at its edge with a solid dielectric slab would have caused diffraction and phase front distortion in an electromagnetic wave entering its wave receiving face. This has made it difiicult to construct practical reinforced or jointed dielectric Walls for the transmission of electromagnetic waves. However, when the low density body and the solid slab are designed in accordance with our invention so as to have the same dielectric constant as well as the same thickness, diffraction and phase front distortion are substantially reduced.

Example 4 In Figure 4 is illustrated in isometric view a cut-away section showing the dielectric body 48 of Figures 1a and lb sandwiched between two dielectric walls 50 and 52 having substantially the same dielectric constant as the body and being placed contiguous with its wave receiving faces 54 and 56. The assembly behaved effectively as a single dielectrically homogeneous panel to electromagnetic waves received through its faces. From an electrical viewpoint it was immaterial whether the walls 50 and 52 were thicker and the dielectric body 48 was thinner, as long as the total thickness remained the same. This provided greater independence of structural design variables from electrical design variables than had been found in the prior art.

For the purpose of describing my invention, certain specific embodiments and materials have been illustrated, but it is to be understood that the invention is not to be limited thereto, since it is evident that such other embodiments and materials are contemplated as are within the spirit and scope of the invention.

What I claim is:

1. A dielectric body for transmission of electromagnetic waves, comprising a substantially regular supporting structure of dielectric material in the form of a plurality of regularly positioned Walls disposed at a high angle toward the wave receiving face of said body, and metallic particles supported by said Walls substantially uniformly distributed in electrically insulated relation along said walls, the effective size of spaces defined by said walls being below the cut-ofi wavelengths of electromagnetic waves to be transmitted.

2. A dielectric body for transmission of electromagnetic waves, comprising a substantially regular cellular supporting structure of dielectric material providing walls extending at a high angle to the wave receiving face of said body, and metallic particles supported by said cellular structure substantially uniformly distributed in electrically insulated relation along the walls of said cellular structure, the effective size of cells of said cellular supporting structure being below the cut-off wavelengths of electromagnetic waves to be transmitted.

3. A dielectric body for transmission of electromagnetic waves, comprising a substantially regular cellular structure of dielectric material composed of repeating cells of substantially uniform size and configuration providing walls extending at a high angle to a wave receiving face of said body, and metallic particles supported by said cellular structure substantially uniformly distributed in electrically insulated relation in sufficient concentration to provide a high dielectric constant along the Walls of said cellular structure, the effective size of said cells being below the cut-off wavelengths of electromagnetic waves to be transmitted.

4. A dielectric body for transmission of electromagnetic waves as defined in claim 3 in which the walls of said cellular structure define prisms substantially normal to the wave receiving face of said body, the effective size of said cells being below the cut-off wavelength of electromagnetic Waves to be transmitted.

References Cited in the file of this patent UNITED STATES PATENTS

US2840811A 1954-05-17 1954-05-17 Dielectric bodies for transmission of electromagnetic waves Expired - Lifetime US2840811A (en)

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2973294A (en) * 1957-09-09 1961-02-28 Hexcel Products Inc Fan-shaped honeycomb and method of making same
US2985880A (en) * 1958-04-24 1961-05-23 Edward B Mcmillan Dielectric bodies for transmission of electromagnetic waves
US3018209A (en) * 1957-02-19 1962-01-23 Dijksterhuis Fokko Panel with cellular inside structure
US3049464A (en) * 1956-11-28 1962-08-14 Sperry Rand Corp Process of manufacturing metalized plastic microwave lens
US3070198A (en) * 1959-09-29 1962-12-25 Haskell Boris Honeycomb structures
US3124798A (en) * 1954-06-11 1964-03-10 Reflection-free damping structure for
US3137000A (en) * 1959-08-10 1964-06-09 Gen Electric Co Ltd Quarter-wave reflecting plate with support core of resin-impregnated paper honeycomb
US3168432A (en) * 1961-12-22 1965-02-02 Thore M Elfving Core material
US3231663A (en) * 1962-11-01 1966-01-25 Schwartz Edward Electromagnetic shield having multiple electroconductive passages
US3871001A (en) * 1972-11-15 1975-03-11 Hitco Radome
US3886558A (en) * 1972-08-04 1975-05-27 Secr Defence Brit Artificial dielectric material for controlling antennae patterns
US6747607B1 (en) * 1988-02-12 2004-06-08 The Directv Group, Inc. Radiation power limiter

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2511610A (en) * 1944-11-16 1950-06-13 Hazeltine Research Inc High-frequency electromagneticwave translating element
US2677056A (en) * 1950-07-28 1954-04-27 Elliott Brothers London Ltd Aerial system

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2511610A (en) * 1944-11-16 1950-06-13 Hazeltine Research Inc High-frequency electromagneticwave translating element
US2677056A (en) * 1950-07-28 1954-04-27 Elliott Brothers London Ltd Aerial system

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124798A (en) * 1954-06-11 1964-03-10 Reflection-free damping structure for
US3049464A (en) * 1956-11-28 1962-08-14 Sperry Rand Corp Process of manufacturing metalized plastic microwave lens
US3018209A (en) * 1957-02-19 1962-01-23 Dijksterhuis Fokko Panel with cellular inside structure
US2973294A (en) * 1957-09-09 1961-02-28 Hexcel Products Inc Fan-shaped honeycomb and method of making same
US2985880A (en) * 1958-04-24 1961-05-23 Edward B Mcmillan Dielectric bodies for transmission of electromagnetic waves
US3137000A (en) * 1959-08-10 1964-06-09 Gen Electric Co Ltd Quarter-wave reflecting plate with support core of resin-impregnated paper honeycomb
US3070198A (en) * 1959-09-29 1962-12-25 Haskell Boris Honeycomb structures
US3168432A (en) * 1961-12-22 1965-02-02 Thore M Elfving Core material
US3231663A (en) * 1962-11-01 1966-01-25 Schwartz Edward Electromagnetic shield having multiple electroconductive passages
US3886558A (en) * 1972-08-04 1975-05-27 Secr Defence Brit Artificial dielectric material for controlling antennae patterns
US3871001A (en) * 1972-11-15 1975-03-11 Hitco Radome
US6747607B1 (en) * 1988-02-12 2004-06-08 The Directv Group, Inc. Radiation power limiter

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