Communications: radio wave antennas – Antennas – Balanced doublet - centerfed
Reexamination Certificate
1998-09-22
2001-03-20
Wimer, Michael C. (Department: 2821)
Communications: radio wave antennas
Antennas
Balanced doublet - centerfed
C343S805000, C343S881000
Reexamination Certificate
active
06204824
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to antennas for receiving transmitted signals, and more particularly to folded dipole antennas.
2. Description of the Related Art
In order for televisions and radios to receive transmissions, they must be equipped with antennas. One such type of antenna is known in the art as a “folded dipole” antenna. A conventional folded dipole antenna is shown in wire schematic form in FIG.
1
.
FIG. 1
shows the direction of current flow in a conventional folded dipole. Conventionally, the overall length of a folded dipole is dimensioned equal to ½ the wavelength of a signal it is intended to receive. Thus, if a signal has a frequency of approximately 72 MHz (i.e., TV channel 4) and has a wavelength of approximately 4.0 m, the folded dipole would optimally be approximately 2.0 m in length. One such conventional folded dipole antenna is the TERK TV-50, the teaching of which is hereby incorporated by reference. Smaller antennas are available for FM radio reception, for example, the TERK-FM antenna, the teaching of which is herein incorporated by reference.
The above conventional folded dipole antenna suffers from several drawbacks. Primarily, because it is typically made as a single solid piece, it is very cumbersome. For example, the TERK TV-50 antenna is 76 inches long. As a result of this great size, the conventional folded dipole is difficult to carry, difficult to mount, and difficult to install. Further, from a manufacturing and sales perspective, the conventional device is difficult to store, difficult to transport, difficult to package, and difficult to display. Its height and width are typically not large, however its length is problematic at best.
Accordingly, it is an object of the invention to provide a folded dipole antenna that is not as cumbersome as conventional folded dipole antennas.
It is another object of the invention to provide a folded dipole antenna that is easy to carry, mount, install, store, transport, package, and display.
SUMMARY OF THE INVENTION
The above and other objects are achieved by the invention, which is an antenna for receiving electromagnetic signals, having a body section housing electronic components and at least two arm sections housing a folded dipole conductor. The arm sections are attached to the body section and the folded dipole conductor is electrically connected to the electronic components. The arm sections are preferably disposed on opposite sides of the body section. At least one of the arm sections is movable between a first extended position and a second collapsed position; an overall length of the antenna is smaller when the movable arm section is in the second collapsed position as compared to the first extended position.
In a preferred embodiment, the antenna has a body section, housing electronic components, the body section having hinged portions, and at least two arm sections housing a conductor, hingedly attached and electrically connected to the body section at the hinged portions, disposed on opposite sides of the body section. The arm sections pivot about the hinged portions and are movable between a first extended position in which the arm sections extend from the body in substantially opposite directions to a second collapsed position in which the arm sections extend from the body section subtending an angle of substantially less than 180°. Preferably, the arm sections extend from the body section in substantially the same direction when in the second collapsed position. The antenna is preferably a folded dipole antenna.
A wire conductor is provided in the arm sections and is electrically connected to the body section. The wire has a section that is external to both the arm and body sections; that is, the wire conductor passes along the arm section, passes out of one or more holes in the arm section external to the antenna, and enters the body section to be electrically connected therein. Preferably, the external section of the wire conductor is provided with slack so that the arm sections may be freely moved from the first extended position to the second collapsed position with ease and without putting strain on the conductor.
Preferably, the antenna includes a locking mechanism for securing the arms in the extended or collapsed positions. The locking mechanism is preferably structured as follows. Each of the hinged portions has a hub fixedly attached to the body section and a bore formed in each of the arm sections. The hub is disposed in the bore. The locking mechanism includes at least one protuberance or ridge disposed on either the hubs or the inner walls of the bores and at least two indentations or grooves formed in the other of the inner walls of the bores and the hubs, the protuberance being selectively engageable in the indentations. When the protuberance is engaged in a first indentation, the arm section is secured in the first position, and when the protuberance is engaged in a second indentation, the arm section is secured in the second position. Alternatively, one indentation and two protuberances may be employed.
Preferably, the antenna has mutual inductance cancelling coils disposed at opposite ends of the folded dipole for the purpose of further reducing the length of the VHF element of the antenna. Additionally, the antenna is preferably provided with a UHF element including a printed circuit board having a printed UHF element and an amplifier.
REFERENCES:
patent: 3290689 (1966-12-01), Rieth
patent: 5886669 (1999-03-01), Kita
patent: 5892484 (1999-04-01), MacGahan
Davi Leonard A.
Gilbert Harvey E.
Levisohn, Lerner, Berger and Langsam
Recoton Corporation
Wimer Michael C.
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