Folded spiral antenna for a portable radio transceiver and method of forming same

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGS.
1 and 2, a planar folded spiral antenna 100 for a portable two-way radio transceiver includes a feed-point 101 and 101' positioned on one edge of a ground substrate 102.
The antenna 100 includes a first spiral element 103 and a second spiral element 105 with each element comprised of a plurality of substantially linear segments.
The segments are inter-connected in a substantially rectangular configuration successively reduced in size so as to form each respective spiral element.
Although FIGS.
1 and 2 show the antenna 100 in a substantially rectangular shape, it will be evident to those skilled in the art the other shapes such as a substantially square or circular configuration can be also used.
Furthermore, although FIG.
2 shows the antenna 100 in a homogeneous background above the ground substrate 102, it will be evident to those skilled in the art the other background configurations such as layered dielectric materials can be also used above the antenna and/or between the spiral structure and the ground substrate.
Thus, the configuration shown in FIG.
1 could be positioned on one side of a single supporting substrate (such as a PC board) above the ground substrate in order to conserve space and provide an ease in manufacturing.
Furthermore, it will be evident to those skilled in the art the ground substrate can also take other forms such as a two-way radio or a cellular phone.
The plurality of linear segments forming the first spiral element 103 and the plurality of segments forming the second spiral element 105 are positioned in a parallel relationship such that each of the respective segments are in the same plane.
As best seen in FIG.
2, the folded spiral antenna is constructed as a uni-planar structure permitting the antenna to occupy a very limited space within a portable two-way radio housing.
Conductive runners or traces are used as radiators and form both the first spiral element 103 and the second spiral element 105