US2931034A - Variable inductance for loading antenna - Google Patents

Description

March 29, 1960 J. E. R. HARRISON ETAL VARIABLE INDUCTANCE FOR LOADING ANTENNA Original Filed Feb. 8, 1957 INVENTORS. JOHN EUGENE ROGER HARRISON. By SHOLLY KAGAN ,6, QM 54w 7%. 24

ATTORNEYS,

United States Patent VARIABLE lNDUCTAN CE FOR LOADING ANTENNA John Eugene Roger Harrison, Bedford, and Sholly Kagan,

Newton Highlands, Mass., assignors to Avco Manufacturing Corporation, Cincinnati, Ohio, a corporation of Delaware Application February 5, 1958, Serial No. 715,165, which is a division of application Serial No. 639,075, February 8, 1957. Divided and this application July 7, 1958, Serial No. 746,823

3 Claims. (Cl. 343-750) The present invention relates to an antenna of rugged, waterproof construction which is particularly well adapted for use in a portable communication set.

This application is a division of our copending patent application Serial No. 715,165, filed February 5, 1958, and entitled Transistorized Portable Communication Set, which in turn is a division of our copending patent application Serial No. 639,075, filed February 8, 1957, also entitled Transistorized Portable Communication Set, both of which are assigned to the same assignee as the present application and invention. We claim the benefits of the original filing date of February 8, 1957.

The general objects of the invention are as stated in the aforementioned copending patent applications.

Specifically, the present invention has as its principal object the provision of a readily adjustable, rugged loaded whip antenna construction for portable transmitter-receivers, the antenna being tunable over a range of carrier frequencies. A further object of the invention is to provide the combination of a normally open power switch, an antenna, a transmitter-receiver housing, and means for securing the antenna to the housing and simultaneously closing the power switch.

For a better understanding of the present invention, together with other and further objects, advantages, and capabilities thereof, reference is made to the following description of the accompanying drawings, in which:

Fig. 1 is a perspective view, broken away, of a transistorized portable transmitter-receiver in accordance with the invention of our parent patent application, Serial No. 715,165, filed February 5, 1958, entiled Transistorized Portable Communication Set, showing the mounting of the antenna in accordance with the present invention on the transmitter-receiverg I Fig. 2 is an elevational view of the antenna, that portion of the transmitter-receiver to which the antenna is secured being shown in section, and the antenna rod being partially broken away to facilitate illustration; and

Figs. 3 and 4 are elevational views of the central portion of the antenna, with various parts broken away and others shown in section.

Referring now generally to Figs. 1 and 2, the construction there shown comprises an antenna 11 and a housing 12. As best shown in Fig. 2, the antenna is secured to the housing by a base 16 which snugly but slidably fits in wedge-like manner into a notch 17, the latter being formed integrally with the housing 12 in such a manner as to complement the beveled edges of the base. A spring-biased push button 19 of a normally open power switch 20 is disposed below the base in such a way that placement of the base in the notch causes the base to depress the push button by cam action so as to close'the power circuits of the transmitter-receiver, as shown in detail in our aforementioned parent patent application, to which reference is made for a detailed showing.

The novel whip antenna shown in Figs. 2-4 comprises an upper metallic rod 240, a lower metallic rod 241, and

2,931,034 Patented Mar. 29, 1960 adjustable-inductance loading means between these conductive rods. To facilitate transportation, each of the rods may comprise a number of hollow metallic sections joined with a forced telescopic fit, as shown at 249.

A continuous flexible wire 250 is located within the upper rod, and a similar wire is within the lower rod. When the antenna is made in tubular sections, the several sections may be detached from each other and conveniently folded in order to save space.

The lower rod is secured to a cap 242 formed as an integral part of a cylindrical sleeve 257. A Litz wire loading inductance or coil 243 is wound on a cylindrical bobbin 244. The upper portion of the bobbin is axially bored, as shown at 251, to receive a cylindrical container 245 of a synthetic fibre material, within which is disposed an iron or ferrite tuning slug. In order to provide for axial positioning or displacement of the tuning slug relative to coil 243, and therefore tuning of the antenna, the lower portion of the bobbin is internally screw-threaded at 246. Container 245 is formed with an outward projection 247 which engages the groove of the thread 246 in such a way that rotation of the bobbin 244 and resultant thrust of the screw thread causes the container 245 to move upwardly or downwardly, depending on the direction of rotation of the bobbin.

The top rod 240 is secured to a generally circular cap 253 formed integrally with bobbin 244. The cap 253 is secured to an outer sheath 248 in rigid assembly, waterproofing being effected by the provision of a plastic O-ring 254, placed in a groove which is formed in cap 253. Screw 255 serves as a binding post for one lead of coil 243 and projects from the exterior of the cap 253 through the top rod 240. The arrangement is such that the top rod 240, cap 253, O-ring 254, bobbin 244, and manually operated sheath 248 are turned in unison to effect adjustment of the axial position of slug container 245 relative to the coil 243.

Formed integral with the lower cap is the base 256 of a sleeve 257. The sleeve is slotted at 258 to permit contact of projection 247 (extending through the slot) with the screw thread 246 in the bobbin. Sleeve 257 is provided with an interior bore in continuity with the interior bore 251 of bobbin 244. The sleeve fits over container 245 and provides for wide loading adjustment. In

order to secure the sheath and bobbin in axial position relative to the base 256 of the sleeve, such base is formed with an annular groove 259, formed to receive and to engage a complementary projection 26%) secured to the sheath 248. A water-tight plastic O-ring 268 is located in an annular groove in cap 242. From the foregoing it will be seen that as sheath 248 and bobbin 244 are turned, sleeve 257 and its base 256 and cap 242 are stationary, so that the lead of the thread 246 causes axial or linear displacement of projection 247 and container 245 in order to vary the loading as desired. Accordingly,

slip ring contact arrangements are provided so as to establish a conductive relationship between lead 261 of coil 243 and the lower antenna rod 241. To that end lead 261 is secured to an outer slip ring 262, which rotatably embraces an interior ring 263 permanently conductively connected to lower rod 241 by a pin 264, the rod being biased against the pin by a spring 265.

Describing the adjustment of the antenna in other words, the sleeve 257 and its base 256 and the inner slip ring and the lower cap 242 and the lower rod 241 are stationary members which neither rotate nor move axially. The bobbin 244 and coil 243 and upper cap 253 and upper rod 240 and sheath 248 rotate in unison. Such rotation causes the screw thread 246 to move relative to projection 247. A screw thread moving relative to a projection which cannot rotate causes axial displacement of such projection. To permit such axial displacement,

the slug container 245 and its projection 247 are mounted with one degree of freedom relative to sleeve 257 to permit axial displacement within the sleeve. This is accomplished by providing slot 258 in the sleeve 257, which slot permits axial movement of projection 247. The net result of the foregoing is that when sheath 248 is man ually rotated in one direction or the other, the slug container 245 and the magnetic slug are advanced or retracted relative to the coil 243.

The antenna is rugged, of small size, collapsible, light in weight and waterproof, and it maintains efiicient operation over a substantial tuning range.

While there has been shown and described what is at present considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various modifications and changes andsubstitutions of equivalents may be made therein within the true scope of the invention as defined by the appended claims.

What is claimed is:

l. A waterproof adjustable loading coil for an antenna comprising a relatively non-rotatable sleeve having an axial slot formed therein, a slug tube disposed at least in part within the sleeve and provided with a projection extending through said slot, a concentric bobbin rotatably mounted on said sleeve and formed with a smooth axial bore for receiving said slug tube and a screw threaded portion for receiving said sleeve, the projection extending into the screw thread so that rotation of the bobbin causes axial displacement of the tuning slug relative to the bobbin, a loading inductance coil wound on the end of said bobbin adjacent said bore, a concentric sheath secured to said bobbin for rotating the bobbin, a cap rigidly secured to said sheath and bobbin at the coil end of the bobbin, and a fixed cap secured to the sleeve at the other end of the bobbin, said sheath tightly rotatably fitting said fixed cap.

2. A whip antenna having an adjustable loading coil and comprising upper and lower antenna rods, a relatively non-rotatable sleeve having an axial slot formed therein, a slug tube disposed at least in part within the sleeve and provided with a projection extending through said slot, a concentric bobbin formed with an upper smooth axial bore for receiving said slug tube and a lower screw-threaded portion for receiving said sleeve, said bobbin being rotatably mounted on said sleeve, the projection extending into the screw threads so that rotation of the bobbin causes axial displacement of the tuning slug relative to the bobbin, a loading inductance coil wound on the end of said bobbin adjacent said bore and having leads in circuit with said rods, a concentric sheath secured to said bobbin for rotating the bobbin, an upper cap rigidly secured to said sheath and bobbin at the upper end of the bobbin adjacent the coil, and a lower fixed cap secured to such sleeve at the other end of the bobbin, said rods being individually secured to said upper and lower caps, said sheath tightly rotatably fitting said lower fixed cap.

3. A whip antenna having an adjustable loading coil and comprising upper and lower antenna rods formed of telescoping sections, a relatively non-rotatable sleeve having an axial slot formed therein, a slug tube disposed at least in part within the sleeve and provided with a projection extending through said slot, a concentric bobbin formed with an upper smooth axial bore for receiving said slug tube and a lower screw-threaded portion for receiving said sleeve, said bobbin being rotatably mounted on said sleeve, the projection extending into the screw thread so that rotation of the bobbin causes axial displacement of the tuning slug relative to the bobbin, a Litz wire loading inductance coil wound on the upper end of said bobbin adjacent said bore and'having leads in circuit with said rods, a concentric sheath secured to said bobbin for rotating the bobbin, an upper cap rigidly secured to said sheath and bobbin at the coil end of the bobbin, and a lower fixed cap secured to the sleeve at the other end of the bobbin, said sheath tightly rotatably fitting said lower fixed cap, said rods being individually secured to said upper and lower caps.

References Cited in the file of this patent UNlTED STATES PATENTS 2,206,820 Mydlil July 2, 1940 2,236,151 Marzetti Mar. 25, 1941 2,673,964 Morton et al Mar. 30, 1954 2,841,789 Bassett July 1, 1958

Images