Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-12
Tal Mor: AUTHOR [+1]
An extendible antenna is proposed such that when extended, the radiating element extends above the radio. The radio will include switching to dis- able transmission when the antenna is not extended.
MOTOROLA Technical Developments
by Tal Mor and Gadi Shirazi
phones, to pick up an incoming call. Figures 1 and 2 show possible constructions of the antenna.
Figure 1 is a telescopic solution. The center (hot) element extends from the ground cylinder when in use. When not in use the bottom part of the center conductor extends into the radio housing to allow reception. The ground sleeve is constructed so that together with the center element it forms a coaxial line of the required impedance.
When folded, the TX hot contact (2) is disabled, and the bottom (Rx only) contact (3) is used. Also, the top loading disk of the antenna (4) is shorted to the ground sleeve, so that a shorted quarterwave line is seen at the top of the antenna, presenting an open circuit.
Figure 2 is a flip printed patch antenna. The bot- tom part is ground plated for a microstrip/stripline conductor to be feeding the radiating element. The antenna is connected with a flexible transmission line.
Such constructions have the following advan-
I) The overall radio dimensions are reduced when not in use, and only when in use the full dimensions of the antenna is utilized for bet- ter RF performance.
2) The RF pattern of the antenna is free from dead zones when the antenna is extended.
3) The user is prevented from operating the radio with the antenna in the folded position, which would only provide non-optima1 antenna performance.
An extendible antenna is proposed such that when extended, the radiating element extends above the radio....