Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1999-04-14
2001-08-28
Nguyen, Lee (Department: 2683)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S090300, C455S272000, C455S557000, C343S702000, C343S746000, C343S767000
Reexamination Certificate
active
06282433
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to antennas for mobile communication devices, such as cellular telephones, and more particularly to a slot antenna for a mobile communications device to allow the mobile communications device to communicate via an RF link with a local area network or computer.
BACKGROUND OF THE INVENTION
Personal communication terminals (PCTs), sometimes referred to as personal digital assistants (PDAs), combine a small, hand-held computer with a cellular telephone. A personal communications terminal can be used to run applications, retrieve and read e-mail, and browse the internet. Also, the PCT can be used as a standard cellular telephone for communication in a cellular network. Such devices often have infrared communications capability to allow the device to be connected to other computers and printers for transferring files or data between the devices. One drawback to infrared communications is that it requires direct line of sight between the connected devices. This requirement greatly limits the ability to connect to computers that are connected to an existing local area network (LAN) since all obstructions in the direct line of sight between the connected devices must be removed.
It is also known to use a low-power short-range radio transceiver to provide an RF link with an existing computer or LAN. An RF link does not require direct line of sight between the connected devices and is, therefore, more flexible than an infrared link. Such wireless networks are often used for home networks where computers reside in different rooms. One problem with adopting wireless network technology for use in a cellular phone is that two separate antennas are required because the short-range transceiver used for communications with another computer operates in a different frequency band than the cellular phone transceiver. There is also a problem with interference since both transceivers may be active at the same time. Therefore, it is necessary to separate the antennas to avoid interference. This presents a problem in small, hand-held devices, such as PCTs.
SUMMARY OF THE INVENTION
The present invention relates to antenna systems for personal communications terminals (PCT) that combine a cellular telephone and application processing unit (APU). The APU functions as a small, palm top computer that is capable of running application programs, such as a personal information manager, e-mail program, and web browser. The APU includes a mobile computing interface (MCI) module having a short-range RF transceiver for connecting the APU to a nearby computer or local area network.
An external dipole antenna is used for long-range communications with a cellular communication network. The MCI module employs a slot antenna for communications with the external computer. The housing of the PCT is made of a conductive material and serves as the ground plane for the slot antenna. A one-half wave length slot is formed in the housing and functions as the radiating element of the antenna. The MCI module is electrically coupled to the slot antenna. In the preferred embodiment of the invention, the MCI module is inductively coupled to the slot antenna. The MCI module includes a coupling loop that is placed in close proximity to one end of the slot in the housing. During transmission, the voltage signal across the coupling loop is transferred to the slot antenna which, in turn, radiates electromagnetic waves. Similarly, electromagnetic waves acting on the slot antenna will induce a current in the coupling loop during reception of a transmitted signal.
In some embodiments, the PCT also includes an optional infrared module that allows communications between the APU and the nearby computer or local area network via an infrared link. The infrared module is preferably placed behind the slot so that infrared signals transmitted and received by the infrared module pass through this slot. Thus, there is no need to form an additional opening for the infrared link.
REFERENCES:
patent: 4704581 (1987-11-01), Clark
patent: 0851530A2 (1998-07-01), None
patent: 2325091A (1998-05-01), None
Haartsen, Jaap, “Bluetooth-The Universal Radio Interface for Ad Hoc, Wireless Connectivity,” Ericsson Review No. 3, 1998, pp. 110-117.
Coats & Bennett
Ericsson Inc.
Nguyen Lee
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