Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1998-11-06
2001-02-20
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S900000, C343S901000
Reexamination Certificate
active
06191741
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to antennas for personal computer card modems or radios.
2. State of the Art
Integrated circuit cards, particularly cards conforming to the Personal Computer and Memory Card International Association (PCMCIA) standards, have become a mainstay of mobile computing. PCMCIA cards are available in a variety of form factors including, in order of increasing thickness, Type I, Type II, and Type III cards. A variety of devices use the PCMCIA format including memory cards, modems, disc drives, etc. In particular, the development of mobile computing has resulted in an increased demand for wireless modems.
An example of an antenna for use with a PCMCIA modem card is described in the patent, Stein et al., U.S. Pat. No. 5,628,055. This reference shows a PCMCIA card with a conventional rotatable antenna.
It is desired to have improved antenna for use with a PCMCIA card.
SUMMARY OF THE INVENTION
The present invention generally relates to an antenna for a use with a personal computer card modem having a “closed” position and an “expanded” position. The antenna has two main elongated elements: a first antenna element and a movable second antenna element. In the “expanded” position, the two antenna elements are electrically connected to form a single large antenna, which is connected to an antenna port through an impedance matching circuit. In the “closed” position, the movable second antenna element is directly connected to the antenna port by-passing the impedance matching circuit.
The antenna can thus work in two different configurations. The operation of the antenna does not rely on the user remembering to expand the antenna. The bypass switch allows the shorter antenna configuration to have a good impedance match and thus improves the gain of the shorter antenna configuration. In one embodiment of the present invention, each of the two antenna elements is about a fourth of the length of the center wavelength transmitted/received. Thus, the expanded antenna is roughly a half wavelength antenna, and the closed antenna is roughly a quarter wavelength antenna. The impedance matching for the “closed” quarter wave length antenna is improved when the matching circuitry for the “extended” half wavelength antenna is by-passed.
In one embodiment, the first antenna element is a conductive trace formed on a circuit board. The impedance matching circuit can be placed on the circuit board, as well.
The base of the second antenna element preferably forms a contact for selectively connecting to a bypass switch or to the top of the first antenna element. The second antenna element can be shaped so that it is preferentially held in either the fully closed or fully extended positions. This can be done by making the antenna element thicker at the conductive base to allow a friction fit both at the fully extended and fully closed positions.
REFERENCES:
patent: 4270128 (1981-05-01), Drewett
patent: 5212491 (1993-05-01), Chin et al.
patent: 5455595 (1995-10-01), Yokoyama et al.
Gauld Craig S.
Gleener Andrey
Vanderhelm Ronald J.
Burns Doane , Swecker, Mathis LLP
Le Hoang-anh
Sierra Wireless Inc.
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