This covers the frequencies of 2,400 MHz through 2,440 MHz. Our goals were to achieve a higher gain than the internal card antenna located in a common PCMCIA wireless card, smaller size and greater portability than current external antennas and omni-directionality for use in a mobile enviroment.
Our gain was as high as 8 dB over the best gain of the internal antenna in the Lucent Bronze card. Our overall dimensions were 3x3.75x3.75 centimeters. We fed our antenna using 50 Ohm thin coax and connecters rated for 2.4 GHz, probably availible at your local Radio Shack with the exception of a special pigtail that can be purchased from nearly any wireless networking vendor. The antenna was fabricated from a short section of copper (water) tubing often used in plumbing, copper foil and a piece of copper thin single sided copper board (fiberglass board plated with copper on one side). Fabrication from aluminum may also work well provided a suitable insulater electrically seperates the disk and the cone (like a rubber stopper). Our final impediance was 56 + j 7.5 and resulting SWR was calcuated at 1.4 using a slotted line.
http://www.timgineer.com/index.php/?page=projects&old_project=80211b_Discone
