1996 - 2016
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.
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By most accounts, Wireless Local Area Network (WLAN, Wi-fi) first began in 1971 when a wireless computer network was implemented (dubbed the AlohaNet) at the University of Hawaii. In 1990 AT&T, developed WaveLAN, a Direct Sequence Spread-Spectrum (DSSS) that exhibited superior interference immunity. After many versions of designs using discrete components, in 1996, Harris (now Intersil) introduced their PRISM WLAN chipset. Needing a standard to guarantee interoperability, in 1997, the Institute for Electrical and Electronics Engineers published the first specification for IEEE 802.11 - 2.4 GHz, 2 Mbps, using Frequency Hopping (FH) and DSSS. In 1998, the ETSI HomeRF standard was developed for 2.4 GHz, 1.6 Mbps, Wideband Frequency Hopping. 1999 saw the publication of the IEEE 802.11b standard - 2.4 GHz, 11 Mbps, DSSS. With the unlicensed 2.4 GHz ISM band being crowded with existing WLAN, Bluetooth, ZigBee and microwave ovens, and with a need for higher data rates, in 1999 the IEEE released its 802.11a standard, which moved up into the 5 GHz ISM band, and provided 54 Mbps, OFDM data. In 2000, the ETSI HiperLAN2 emerged - 5 GHz, 54 Mbps, OFDM, connection-oriented QoS. Alas, the difficulty with mass-producing high yielding, inexpensive systems at 5 GHz forced, combined with revolutionary modulation methods, drove the IEEE in 2003 to provide a new high data rate “g” spec for operation back in the 2.4 GHz band, but offering the same data rate as the “a” spec 802.11g - 2.4 GHz, 54 Mbps, OFDM, compatible with 802.11b. Now, 802.11n is in the works for 2.4 GHz operation yielding greater than 100 MHz data rates.
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