An antenna for a wireless communicating device can be set at a precise frequency, in the as formed state. A coil antenna is precisely held in a mold, while an appropriate plastic is molded therearound, with no distortion of the coil, to fix a precise shape for the coil. The recovered, plastic-encased coil requires little or no follow-up treatment before it can be used in a wireless communication device as an antenna.
CROSS-REFERENCE TO RELATED APPLICATION
This application is a divisional application of U.S. patent application Ser. No. 08/415,336, filed Apr. 3, 1995 now U.S. Pat. No. 5,596,797.
An antenna with loading coil is described, which has an especially high Q for longer range communication. The inside of the coil is left empty of solid material while a frame that surrounds the coil is of dielectric material. The wire that forms the coil is constructed so upper and lower wire portions that extend radially inwardly from the ends of the coil, extend at inclines much greater than the wind angle of the coil, and hold metallic coupling slugs away from the opposite ends of the coil. Strips of silicone extend between adjacent coil turns and are mounted on the coil, to minimize vibrations while using a minimum of dielectric material close to the coil. By combining these improvements into a practical commercial coil, applicant has raised the coil Q by 29.5% from the Q of his previous antenna which had the highest Q of citizen band antennas on the market.
A helical coil and a top-helical type antenna using the same, wherein the helical coil has a plurality of either substantially U-shaped or nearly V-shaped branch portions made of a thin metallic sheet material. The branch portions are connected continuously in a manner to place their open ends alternately inversely, and the branch portions alternatively curve toward an obverse side and a reverse side of the metallic sheet to form each turn of the coil. A method for producing the helical coil includes continuously die cutting a member on a belt-shaped strip of electrically conductive metallic sheet, and alternately placing a plurality of either substantially U-shaped or substantially V-shaped branch portions with their open ends inversely. These substantially U or V-shaped branch portions are then connected with each other in the shape of a letter, with connection to the metallic sheet being held only by linkage portions at opposite sides. The helical coil is formed by alternately curving the branch portions of each of the members in a shape of substantially circular arc toward an obverse side and a reverse side of the metallic sheet. A bobbin is formed connecting each turn of the helical coil by either insert-injection molding or outsert-injection molding of electrically nonconductive material on the individual helical coil formed on metallic sheet and subsequently the linkage portions are sheared off of the metallic sheet.
An antenna includes a precision micro-molded plastic spacer and a metal insert. The plastic spacer is configured for mounting to a printed circuit board (PCB) to maintain the metal insert a predetermined distance from a ground plane. Micro-insert-molding techniques produce tight mechanical dimensions including those which define the antenna height, ensuring reliable and consistent antenna electrical performance.
A method for tuning an antenna includes cutting a portion of a metal pattern molded with a plastic insert to adjust electrical characteristics of the antenna. Tuning can be performed by cutting the metal pattern or by cutting the completed antenna including both the metal pattern and the plastic insert.
An efficient and repeatable method for manufacturing a protectively coated helical conductor antenna. The helical conductor is threaded onto a temporary, removable support, such as a bolt including a shaped head and a shank having threads to hold the helical conductor. After being threaded on the bolt, the entire winding and the bolt shank are placed within an injection mold cavity. The mold also includes a recess outside of the injection cavity for accommodating the bolt head, with the recess being shaped to permit a specific orientation for the bolt. The shape of the bolt head and the recess define a repeatable orientation for the bolt and helical conductor. As a result, the point of injection relative to the helical winding may be exactly repeated time and time again. This allows selection of an injection point relative to the helical winding that produces minimal deformation, and the obtainment of consistent results thereby reducing variation and necessary manufacturing tolerances.