Half-wave retractable antenna with matching helix

Details Half-wave retractable antenna with matching helix Half-wave retractable antenna with matching helix

1998-06-05

2000-04-18

Wong, Don

Communications: radio wave antennas

Antennas

With radio cabinet

343895, H01Q 124

Patent

active

060520892

ABSTRACT:
A retractable whip antenna incorporating a matching base loading helix for use in mobile communications devices is disclosed. The antenna functions without the use of a matching circuit since selection of the radiating elements provides a constant input impedance to the transceiver circuitry. The resulting antenna provides excellent gain over the PCS frequency band, low SAR values, circuit design flexibility and low cost. In a preferred embodiment, the retractable whip is comprised of a radiating element with an electrical length of 1/2 wavelength and having a first end attached to a conductive spring contact. The base loading helix comprises a radiating helical element with an electrical length of 1/4 wavelength and having a first end connected to a mobile transceiver circuit and a second end comprising a conductive capturing coil. The radiating whip element is constrained within the coil of the helical element and is freely moveable to an extended or a retracted position. When the whip element is in the retracted position, the whip element is disconnected from the radiating circuit. When the whip element is in an extended position, an electrical connection is formed via contact between the conductive spring contact and the conductive capturing coil, wherein the helical element effectively base loads the whip element so that the two radiating elements have a combined electrical length of 3/4 wavelength.

REFERENCES:
patent: 4121218 (1978-10-01), Irwin et al.
patent: 4868576 (1989-09-01), Johnson
patent: 5343213 (1994-08-01), Kottke et al.
patent: 5446469 (1995-08-01), Makino
patent: 5612704 (1997-03-01), Cole
patent: 5635943 (1997-06-01), Grunwell
patent: 5717408 (1998-02-01), Sullivan et al.
patent: 5734351 (1998-03-01), Ojantakanen et al.
patent: 5861859 (1999-01-01), Kanayama et al.

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