Patent ID: 6229498
Filing Date: 2001-05-08
Classification: H01Q

Abstract:
A helical antenna comprising:a plurality of antenna elements, each of which antenna elements having a signal input unit for an electric power feeding signal;feeding means having at least plural signal output units corresponding to the number of said signal input units, for outputting the feeding signals from the respective signal output units while giving a predetermined phase difference to said feeding signals;a first holding mechanism for holding the respective signal input units of said antenna elements on the substantially same circumference, said first holding mechanism is constructed of a tube body, an adjoining portion of which is located within a plane, said adjoining portion containing an edge plane of said tube body, and the respective signal input units of said antenna elements are held at said adjoining portion of said tube body;a second holding mechanism for holding the respective signal output units of said feeding means on a line which is located perpendicular to said plane where said circumference is positioned, and also which passes through an essential center of said circumference; anda plurality of feeding lines for connecting the respective signal input units of the respective antenna elements to the respective signal output units of said feeding means with maintaining the individual relationship among them;said feeding means includesa circuit board; anda feeding circuit mounted on said circuit board, and having the respective signal output units, for processing said feeding signals to output the processed feeding signals from the respective signal output units, while applying a predetermined phase difference to the processed feeding signals;said circuit board contains an arranging unit where the respective signal output units are arranged;said circuit board is held by said tube body in such a manner that said arranging unit is located within a plane which is positioned in parallel to such a plane involving a plane which passing through said edge plane of the tube body; andthe stacked layer board is held by the tube body with a planar direction of the board being parallel to a direction of the axial center of the tube body.