Helical antenna for a portable radio apparatus
First Claim
1. A helical antenna for a portable radio apparatus comprising:
- a screw shaped emitting element having one feeder terminal and a plurality of communication band switching terminals provided with gaps therebetween in the longitudinal direction of the antenna;
a switch for short circuiting and disconnecting two or more terminals among said plurality of communication band switching terminals;
a drive circuit for driving said switch; and
a control unit which operates said drive circuit in accordance with externally applied signals;
wherein when a current greater than a predetermined value is applied to said switch the impedance thereof becomes lower to short circuit said communication band switching terminals; and
said drive circuit applies a current greater than said predetermined value to said switch when said drive circuit receives a switching signal from said control unit and said control unit generates simultaneously said switching signal for changing resonance frequency of the antenna and channel data for determining reception frequency of a receiver.
2 Assignments
0 Petitions
Accused Products
Abstract
A helical antenna is provided for portable radio apparatus characterized in having one communication band switch and having two separated communication bands, or a broad communication band. The helical antenna comprises a screw shaped emitting element having one power supply terminal and two communication band switching terminals, a switch which short circuits and disconnects the two communication band switching terminals, and a switch drive circuit which drives this switch, and in accordance with an externally applied signal, the switch drive circuit short circuits or disconnects the switch, and by means of the disconnection or short circuiting of the two communication band switching terminals, the resonance frequency is switched.
24 Citations
6 Claims
-
1. A helical antenna for a portable radio apparatus comprising:
-
a screw shaped emitting element having one feeder terminal and a plurality of communication band switching terminals provided with gaps therebetween in the longitudinal direction of the antenna; a switch for short circuiting and disconnecting two or more terminals among said plurality of communication band switching terminals; a drive circuit for driving said switch; and a control unit which operates said drive circuit in accordance with externally applied signals; wherein when a current greater than a predetermined value is applied to said switch the impedance thereof becomes lower to short circuit said communication band switching terminals; and said drive circuit applies a current greater than said predetermined value to said switch when said drive circuit receives a switching signal from said control unit and said control unit generates simultaneously said switching signal for changing resonance frequency of the antenna and channel data for determining reception frequency of a receiver. - View Dependent Claims (2, 3, 4, 5, 6)
-
Specification