Multiple service user terminal

• US 6,122,524 A
• Filed: 11/13/1997
• Issued: 09/19/2000
• Est. Priority Date: 11/13/1996
• Status: Expired due to Term

• Current Assignee: Inmarsat Global Limited (Inmarsat PLC)
• Original Assignee: International Maritime Satellite Organization
• Inventors: Goerke, Thomas
• Primary Examiner(s): TO, DORIS HA
• Application Number:
  US08/970,156
• Time in Patent Office: 1,041 Days
• Field of Search: 455/19, 455/71, 455/77, 455/78, 455/82, 455/83, 455/550-553, 455/101, 455/102, 455/125, 455/131, 455/132, 455/134, 455/179.1, 455/435, 455/13.2, 455/6.1, 455/1, 455/427 , 455/575, 343/702, 343/796, 343/822, 343/725-728, 343/807, 343/895, 343/858, 333/126, 333/124, 333/129, 333/132
• US Class Current: 455/552.1
• CPC Class Codes: H04B 7/18571 for satellites; for fixed or mobile stations

Abstract

A user terminal in the form of a handset 1 is disclosed wherein a common antenna 3 is operative to provide transmission and reception on a plurality of selectable services at different frequencies, the antenna being resonant and matched for at least one of the services, and non-resonant and unmatched for other services. The user terminal handset 1 employs a common antenna 3 directly for that service or those services for which the antenna 3 is matched and resonant. The user terminal handset 1 employs the common antenna 3 unmatched and non-resonant for those services whereon unmatched non-resonant antenna use is acceptable. The user terminal handset 1 comprises means, for approximately or precisely adjusting the match to the common antenna 3 for other services.

Claims

1. A user terminal for use in a communication system that includes a plurality of services provided on a plurality of frequencies, comprising

a common antenna through which the user terminal can selectively access each of said plurality of services, said common antenna being arranged to be matched at the frequency of at least one of said plurality of services;

a selecting mechanism arranged to select between at least first and second operating modes, wherein, in said first operating mode said common antenna is operative as a matched antenna for at least one of said plurality of services, and in said second operating mode said common antenna is operative as an unmatched antenna for at least one other of said plurality of services;

a tuning mechanism responsive to the selection of at least one other of said plurality of services, said tuning mechanism comprises an electrically controllable element for altering the frequency at which said common antenna is matched towards the frequency of said at least one other of said plurality of services; and

a controller operative to monitor the amplitude of signals on said common antenna, said controller being operative to generate a control signal in response to the amplitude of the signals on said common antenna, said control signal being coupled as a controlling input to said electrically controllable element, and said electrically controllable element being responsive to said control signal to move the frequency at which said common antenna is matched towards the frequency of said at least one other of said plurality of services.

2. A user terminal according to claim 1, wherein said selection of at least one other of said plurality of services includes use of a first frequency for radio reception and use of a second frequency for radio transmission, said tuning mechanism being operative to move the frequency at which said common antenna is matched towards said first frequency when said user terminal is in receiving mode and towards said second frequency when said user terminal is in transmission mode.

3. A user terminal according to claim 1, wherein said common antenna comprises plural conductors on a common former, and wherein said terminal comprises switches to select one or more of said plural conductors for use on a particular service.

4. A user terminal according to claim 1, wherein said tuning mechanism comprises an antenna matcher.

5. A user terminal according to claim 1, wherein said selecting mechanism includes a keypad, said keypad having a plurality of keys corresponding to the plurality of services for selecting one of said plurality of services.