US 3538441 A
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NOV4 3, 1970 V TAKASHI TANAKA 3,538,441
ANTENNA HAVING A RECEIVER THEREI-IlA Filed Feb. 23, 1967 's sheets-sheet 1 f/kf/ NVENTOR. TAKASH |V ANAKA WM/Wa ATTORNEY-s Nov. 3, 1970 TAKAsHl TANAKA 3,538,441
ANTENNA HAVING -A RECEIVER 'THEREIN v Filed Feb. 23. 1943*? INVENTOR.
ATTORNEYS Nov. 3, 1970 TAKASHITANAKA- v ANTENNA HAVING A RECEIVER-THEREIN n 3 Sheets-Sheet 3 Filed Feb;V 23. 1967 v l//l INVENTOR. ASHI T NAKA wml TA BY ATTORNEYS United States Patent O Fice 3,538,441 ANTENNA HAVING A RECEIVER THEREIN Takashi Tanaka, Osaka-fu, Japan, assignor to Matsushita Electric Industrial Co., Ltd., Osaka, Japan Filed Feb. 23, 1967, Ser. No. 618,103 Claims priority, application Japan, Feb. 24, 1966,
41/ 17,062; Mar. 28, 1966, 41/ 19,498
Int. Cl. H0411 1/18 U.S. Cl. S25-365 5 Claims ABSTRACT OF THE DISCLOSURE An antenna and receiver assembly comprising a core of a magnetic material having a winding thereon and having a hollow interior, and electronic and/ or mechanical components constituting at least part of a receiver for electromagnetic waves, such as radio waves, are positioned in the hollow interior and coupled to the winding which serves as the antenna for the receiver. A part or the whole of the remainder of the hollow interior is iilled with an insulating adhesive material in order to provide support and strength to the hollow core of magnetic material.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to an antenna for a receiver for electromagnetic waves, such as radio receiver and more particularly to an antenna comprising a magnetic core having a hollow therein in which at least some of the electrical and/ or mechanical components of the receiver are mounted.
Prior art A conventional antenna for use in a receiver, such as a radio receiver comprises a magnetic core having a winding thereon. The magnetic core consists of, for example, a ferrite material having a high magnetic permeability and is usually in the form of a rod, a plate or a tube. It is wellknown that the sensitivity of an antenna having a magnetic core depends upon the ratio of the length to the crosssectional area of said magnetic core. A higher ratio results in a higher sensitivity. As a practical matter, it is not easy to obtain a higher ratio because the maximum length of the magnetic core is limited by the size of the casing containing the radio receiver. It is also diiicult to reduce the cross-sectional area of the magnetic core comprising a ferrite because of the ferrite has poor mechanical strength. For example, a thin rod or plate which is long is easily broken when the receiver is dropped carelessly on the iloor during handling. A tubular core has a higher mechanical strength than a rod core with the same cross-sectional area and length, but the tubular core, has a larger outside dimension than a rod core.
It is desirable that a receiver be small in size. Recent developments in the electronic component industry have succeeded in miniaturizing the electronic components by employing various new elements, for example, transistors instead of electron tubes. Moreover, new techniques such as those for making micromodules and integrated circuits have increased the packing density of the components. On the other hand, it has not been possible to reduce the size of the antenna not without decreasing the sensitivity and/ or the mechanical strength thereof. Therefore, the conventional antenna occupies quite a large space in a radio receiver in comparison with the other miniaturized components and limits miniaturization of a receiver.
SUMMARY OF THE INVENTION It is an object of the present invention to provide an 3,538,441 Patented Nov. 3, 1970 antenna having a high sensitivity, a high mechanical strength and a small volume.
Another object of the invention is to provide an antenna containing therein at least some of the electrical and/ or mechanical components of a receiver.
The antenna according to the invention comprises an assembly of a magnetic core having a winding thereon and a hollow interior, and at least some electronic and/or mechanical receiver components are mounted in the hollow interior, and a part or the whole of the remainder of the hollow interior is lled with an insulation and adhesive material.
BRIEF DESCRIPTION OF THE FIGURES The invention will now be described in connection with the accompanying drawings, in which:
FIG. 1 is a perspective view of one embodiment of an antenna according to the invention;
FIG. 2 is a longitudinal sectional View of the antenna of FIG. l;
FIG. 3 is a perspective view, partly broken away, of another embodiment constructed by the so-called micromodule technique;
FIG. 4 is a longitudinal sectional view of the antenna of FIG. 3;
FIG. 5 is a perspective View, partly broken away,of still another embodiment, in which all the components of the receiver are mounted in the hollow within the antenna core; and
FIG. 6 is a longitudinal sectional view of the antenna of FIG. 5.
DESCRIPTION OF PREFERRED EMBODIMENTS The present invention is an antenna for a receiver for electromagnetic waves, which antenna comprises a magnetic core having a hollow therein and in which hollow various kinds of components are mounted. The provision of the hollow in the antenna core makes the cross-sectional area smaller and increases the ratio of the length to the cross-sectional area. The use of a thin wall for the core results in the said higher ratio, but it also results in a lower mechanical strength. It has been discovered according to the invention that the hollow antenna core can have its mechanical strength improved by mounting electronic components in the hollow interior by means of an insulating adhesive material so that the hollow interior can provide the space necessary for the components of a receiver.
Referring to FIGS. l and 2, reference character 1 designates a magnetic core having a hollow interior 3 and having a winding 2 wound on the magnetic core 1. Said hollow has positioned therein various components 4, comprising, for example, resistors, capacitors and transistors. Said various components are positioned in said hollow by an insulating adhesive material 5 such as organic resin or sealing glass.
According to the invention, the ratio of the length of the core to the cross-sectional area can be increased by making the wall of the magnetic core thinner without increasing the length. The hollow magnetic core having a thin wall can be provided with a high mechanical strength by filling the hollow with insulating adhesive material, and the hollow can provide space for components.
A magnetic core according to the invention can be prepared from any available magnetic material having a high magnetic permeability. `Operable materials are nickel Zinc ferrites, copper zinc ferrites and manganese ferrites. Such errites can be formed into a magnetic core by a per se well-known ceramic fabrication technique. Magnetic powder cores are also operable. Such a powder core can be made by a per se well-known technique; that is, finely divided magnetic powder such as iron powder or permalloy powder mixed with a suitable insulating binding material is compressed into a pressed body. The cross-sectional shape of the magnetic core and the hollow interior can be any form, such as circular, square, rectangular or ellipsoidal.
It is important that the temperature coefficient of thermal expansion of the insulating adhesive material with which the hollow 3 is lled is close to that of the magnetic core. Epoxy resin, silicone rubber and polyester are operable for a magnetic core comprised of nickel zinc ferrites, copper zinc ferrites or manganese `zinc ferrites, Pitch made from coal-tar and wax such as paraffin are also operable as an insulating adhesive material for a magnetic core comprising the above ferrites and powder cores. A sealing glass having a melting temperaturelower than 400 C. is an excellent insulating adhesive material for the magnetic core consisting of the above ferrites and containing components of a high heat resistance, such as wire resistors or glass capacitors, because the sealing glass has a temperature coefficient of thermal expansion very close to those of the above ferrites,
Various components are combined together into a receiver network and are positioned in the hollow of the magnetic core. -One end of the hollow is covered by, for example, a glass plate or a mica plate 6 and then the aforesaid insulating material `S in a liquid state is poured into the hollow from the other end. The necessary lead wires of the receiver network extend through the insulating adhesive material, which is solidified by cooling or curing.
The magnetic core having the various components positioned therein is provided with the winding 2 by a per se well-known method for making an antenna for a receiver and the winding is coupled to the receiver components to serve as the antenna therefor. The antenna according to the invention can contain all of the necessary vcomponents of a receiver except the large components, such as a speaker, and canbe a receiver in which the antenna itself is used as the case.
Referring to FIGS. 3 and 4 showing an antenna having so-called micromodule elements, a hollow ferrite core 11 is made by the usual fabrication techniques, such as extrusion, and a winding 12 is Iwound thereon to pick up magnetic waves concentrated by the core 11. The internal dimensions of the hollow in the core 11 are about 10 x l0 to 12 x 12 mm. An assembly of micromodule elements is inserted into the hollow of the core 11. Electrical cornponents, such as resistors, capacitors, inductors, transistors, diodes (not shown), are mounted or deposited on wafers 13 made of ceramics such as alumina or beryllia. Waters 13 are about 8 x 8 to 10 x 10 mm. in area and 0.3-0.5 mm. thick. Riser wires 14 are connected electrically and mechanically in notches (not shown) in the wafers. in order to insulate the wires 14 from the core, a film of insulator 15 such as polyester lm is positioned against the inner surface of the core 11 before the assembly of wafers 13 and wires 14 is inserted into the hollow, or the assembly consisting of wafers 13 and wires 14 is wrapped with a film of insulator 1S before being inserted into the hollow of the core 11. After insertion, the space within the hollow of the core 11 is lled with the above described insulating material. This is useful not only for strengthening the core, but also for protecting the cornponents from moisture and the like.
When only a small number of elements make up a receiver, such as a receiver for a personal signaling system or a low-class simple radio receiver, all the small parts of the receiwer can be fitted into the hollow of the antenna core. Referring to FIGS. 5 and 6, reference character 21 designates a hollow antenna core and a winding 22 is provided thereon. An assembly of electrical parts 23, such as transistors, inductors, resistors or capacitors, and a battery 24 etc. are positioned in the hollow in the antenna core 21. A switch 25, a volume control 26 and a variable capacitor 27 are mounted in the antenna core so that they can be operated from outside the core.
Only the assembly of parts 23 is cast in a resin such as epoxy. The switch 25, the volume `control 26 and the variable capacitor 27 are attached to-an insulating plate 29 and electrically connected to the assembly of parts 23. In this embodiment, the antenna core also lls the role of the case for the receiver. The receiver can thus be made smaller than would be possible using a conventional antenna because the antenna of the present invention eliminates the need for a case. It is preferable that the Winding and the core be covered by a plastic lm 28 such as vinyl or polyethylene in order to provide a high resistance to moisture.
What is claimed is:
1. An antenna comprising a magnetic core having an unbroken outer annular wall with a winding only on said outer annular wall, said core further having a hollow interior, and receiver components mounted in said hollow interior, and at least a part of the remainder of said hollow interior having an insulating adhesive material therein.
2. An antenna as claimed in claim 1, wherein said magnetic core is made of a ferrite.
3. An antenna as claimed in claim 1, wherein said magnetic core is a magnetic powder core.
4. An antenna as claimed in claim 1, in which said insulating adhesive material completely lls said hollow interior around said components, said insulating adhesive material being selected from the group consisting of epoxy resin, silicone rubber, polyester, pitch, wax and sealing glass.
5. An antenna and receiver assembly comprising a casing of a magnetic material having an unbroken annular wall with a winding thereon and having a hollow interior, said magnetic material casing serving as a magnetic antenna core, a plurality of components in said hollow interior connected to form a receiver for electromagnetic waves, said antenna winding being coupled to said receiver, and at least a part of the remainder of said hollow interior having an insulating adhesive material therein.
References Cited UNITED STATES PATENTS 3,307,108 2/1967 Induni S25-354 XR 3,111,669 11/1963 Walsh 343-788 XR 2,955,286 10/1960 Klein 343-788 XR 1,618,468 2/1927 Palmer B25- 354 3,204,224 8/ 1965 Wollmann 340-174 ROBERT L. GRIFFIN, Primary Examiner R. S. BELL, Assistant Examiner