Impedance matching means between antenna and transmission cable

An antenna assembly for connection to a transmission cable having an inner core conductor and an outer conductive shield, comprising:

• a dielectric printed wire board (PWB) having an upper side and a lower side;
• an antenna body disposed on the upper side of the PWB, including:
• a radiating portion;
• a feed portion electrically connected to the radiating portion;
• and
• a ground portion electrically insulated from the feed portion and the radiating portion;
• and
• an impedance matching means, comprising:
• a first conductive patch on the upper side of the PWB;
• and
• a second conductive patch on the lower side of the PWB, the second conductive patch being electrically insulated from the first conductive patch by the intervening PWB;
• and
• whereby the inner core conductor of the transmission cable electrically connects to the feed portion and the shield of the transmission cable electrically connects to the ground portion, the radiating portion transmits and receives electromagnetic signals, and the impedance matching means effectively matches an input impedance of the antenna assembly to an impedance of the transmission cable.

A method of making an RF antenna assembly, comprising the steps of:

• providing a printed circuit board defining two opposite surfaces;
• forming spaced feed portion and grounding portion on one of said surface;
• forming a properly configured radiation portion on the same one of said surfaces, said radiation portion electrically connected to said feed portion.;
• providing a pair of parallel conductive patches on said two opposite surfaces, respectively with one of said pair of conductive patches electrically connected to said feed portion;
• wherein
• by adjusting relative areas of the patches or changing a relative permittivity of a dielectric material of the printed circuit board between said pair of patches, an impedance of the antenna is matched that of a preselected cable which is electrically connected to the feed portion.