Communications: radio wave antennas – Antennas – With radio cabinet
Reexamination Certificate
2000-02-01
2001-03-20
Phan, Tho (Department: 2821)
Communications: radio wave antennas
Antennas
With radio cabinet
C343S895000
Reexamination Certificate
active
06204818
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a stretchable antenna for mobile phones, and especially to a stretchable antenna capable of increasing capability of signal receiving and emitting.
2. Description of the Prior Art
A conventional antenna for mobile phones is divided mainly into two kinds; they are the quarter-wave and the half-wave antennas. The quarter-wave antennas have lower impedance in servo link, and do not need using of impedance transformers, but they are inferior to the half-wave antennas in the capability of signal receiving and emitting. The half-wave antennas have higher impedance, and need using of impedance transformers in the interior of their mobile phones.
In the recent years, mobile phones tend to be minimized. Half-wave antennas occupy larger space in their mobile phones by using impedance transformers; other redundant parts used further increase their costs. Lengths of half-wave antennas generally are hard to suit modern pocket mobile phones; such lengths are disproportional to the main bodies after assembling. In view of this, pocket mobile phones generally use quarter-wave antennas; however, quarter-wave antennas are evidently insufficient in the capability of signal receiving and emitting even when the rods of antennas as radiators are fully stretched.
In a “Antenna device for portable equipment” U.S. Pat. No. 5,757,325 granted to Saldell, an impedance transformer is evidently used.
In another U.S. Pat. No. 5,661,495 granted to Saldell, a technique is disclosed to use a switching device to separate a quarter-wave antenna when the antenna is retracted; however, it is still insufficient in the capability of signal receiving and emitting.
In another U.S. Pat. No. 5,771,023, a coil antenna for broad bands is disclosed, wherein, a broadband antenna is formed by connecting two coil antennas respectively with a rod of antenna.
A U.S. Pat. No. 5,650,789 provides a retractable antenna for an indoor wireless telephone set, of which two coil antennas are respectively used at the end of a rod of antenna and the telephone set. The coil antenna at the end of the rod of antenna is electrically broken when it is stretched out, but can form electromagnetic coupling with a fixed coil antenna on the surface of an engaging seat when the coil antenna at the end of the rod of antenna is retracted for signal receiving and emitting. This patent still cannot increase capability of signal receiving and emitting by using a quarter-wave antenna.
SUMMARY OF THE INVENTION
The present invention provides a stretchable antenna for mobile phones, wherein, a coil antenna is provided at the end of the rod of antenna which can be stretched to elastically combined with a rod of antenna when is stretched out. When the rod of antenna is retracted, the coil antenna at the end of the rod of antenna enters the interior of a fixed coil antenna in the body of the mobile telephone set in a limiting mode to decouple electromagnetically. Thereby, a stretchable antenna is completed; as a quarter-wave antenna, it can increase capability of signal receiving and emitting when it is stretched out.
In a preferred embodiment of the above stated coupling/decoupling device, an end piece is provided at the end of a rod of antenna. The end piece can be abutted against an annular piece by elastic stretching force of the coil antenna thereabove when the latter is stretched out. And when the rod of antenna is retracted, the bottom end of the coil antenna is limited to separate the end piece from the annular piece and out of contact therewith.
The present invention will be apparent in its novelty and features after reading the detailed description of the preferred embodiment thereof in reference to the accompanying drawings.
REFERENCES:
patent: 4435713 (1984-03-01), Gasparaitis et al.
patent: 5661495 (1997-08-01), Saldell
patent: 5764191 (1998-06-01), Tsuda
patent: 5771023 (1998-06-01), Engblom
patent: 5900839 (1999-05-01), Duperray
Chang Daniel
Chiang Chi-Ming
Auden Technology Mfg. Co. Ltd.
Dougherty & Troxell
Phan Tho
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