Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
1999-10-28
2001-05-29
Le, Hoanganh (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S895000, C343S793000
Reexamination Certificate
active
06239755
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
The present invention relates generally to antennas. More specifically, the present invention relates to a balanced, retractable dipole antenna for mobile phones.
II. Description of the Related Art
Recent advancements in electronics have significantly improved the performance of mobile phones. For example, advancements in integrated circuit technology have led to high performance radio frequency (RF) circuits. The RF circuits are used to construct transmitters, receivers and other signal processing components typically found in mobile phones. Also, advancements in integrated circuit technology have led to a reduction in the size of RF circuits, thereby leading to a reduction in the overall size of a mobile phone.
Similarly, advancements in battery technology have resulted in smaller, lighter and longer lasting batteries used in mobile phones. These advancements have resulted in smaller and lighter mobile phones that operate for a longer period of time on a single charge.
Generally, a user of a mobile phone must be able to communicate with another user or a ground station that can be located in any direction from the user. For this reason, the antenna in the user's mobile phone must be able to receive and transmit signals from and in all directions. Consequently, it is desirable that the antenna exhibit a symmetric radiation pattern having a uniform gain in the azimuth. In addition, it is desirable for mobile phones to have antennas that are retractable.
Unfortunately, antennas found in today's typical mobile phones do not exhibit a symmetric radiation pattern. Mobile phones generally utilize monopole antennas (for example, a whip antenna) that, due to the presence of unbalanced currents, exhibit asymmetric radiation patterns. This is primarily due to the fact that the shape and dimension of a monopole are not equivalent to to the shape and dimension of a ground plane of a printed wire board (PWB) used as a counterpoise, resulting in an unequal current distribution in the monopole and in the ground plane.
As a result, it has been recognized that there is a need for an antenna for a mobile phone that exhibits a symmetric radiation pattern.
SUMMARY OF THE INVENTION
The present invention is directed to a balanced, retractable dipole antenna for mobile phones, such as cellular and PCS phones. The balanced, retractable dipole antenna comprises a first radiator element that is selectively extendable from, and retractable into, a mobile phone casing, a second radiator element, and a counterpoise that is electrically isolated from a printed wire board (PWB) of a mobile phone. The balanced, retractable dipole antenna further comprises a signal balancing means coupled between a signal source and at least the second radiator element and counterpoise to generate first and second signals, respectively. The first and second signals are substantially equal in magnitude but out of phase by 180 degrees. When the first radiator is extended, the first signal is transferred to the first and second radiator elements, and the second signal is transferred to the counterpoise. When the first radiator element is retracted, the first signal is transferred to the second radiator, while the second signal is transferred to the counterpoise and the first radiator element. The first and second signals produce balanced currents, thereby producing a symmetric radiation pattern.
REFERENCES:
patent: 5446469 (1995-08-01), Makino
patent: 5479178 (1995-12-01), Ha
patent: 5635943 (1997-06-01), Grunwell
patent: 5703602 (1997-12-01), Casebolt
patent: 5969684 (1999-10-01), Oh et al.
patent: 6034650 (2000-03-01), Kuramoto
Klemens Guy
Ozaki Ernest T.
Tran Allen Minh-Triet
Brown Charles D.
Dinh Trinh Vo
Hom Raymond B.
Le Hoang-anh
Qualcomm Incorporated
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