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 3×3.75×3.75 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.
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