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14Km 802.11B link test

FRARS members braved the elements to test a 14Km 802.11 Link using home built antenna's.

Written by: G4RFR ( FRARS ) Sunday, 20 January 2002

Click for full size imageToday, Saturday the 19th of January 2002, Paul - G7EYT, Carl - G6NLC and Neil - M1NCD sucessfully completed a 14Km range check with 802.11B equipment and home built antenna's. Paul was located at Whiteways car park on the Purbeck Hills, in Dorset, and Carl was located in Lychett Minster, also in Dorset.

The WX was raining at first, but then it cleared and was good sunshine. I suspest the initial rain had an atmosphere cleaning effect. The remaining water vapour no doubt affected the long microwave path.

The antenna at Paul's site was the tried and trusted Sky mini-dish used in the 6Km experiments, and Carl was using a short back-fire antenna recently built from an internet design.

The short back-fire seemed to perform very well and certainly had the characteristics of having a reasonable amount of gain, and a fairly narrow beam width. The antenna had been optimised for lowest SWR thus ensuring maximum signal transfer from wireless lan card to free space.

The triple image shows, from top to bottom, The view from the Purbecks over Poole and Bournemouth, The system and antenna Carl was using, and finally, a screen shot of the link budget analysis provided by the compaq / lucent software.

The same wireless cards in use were the Compaq WL100 with no diversity switch, and external antenna modification. This mod ensures all RF is transferred to the card via the SMA connection. The other card in use was a compaq WL110 Lucent Waveaccess clone, with no mods, but with an external antenna pig tail connection.

Interestingly, Whilst on the Purbecks, other Access Points could be detected, from at least 6 to 8 Km away.

This test proves that a link is possible over a significant distance, with reasonable bandwidth.

Other antenna's tested were; A lucent 14Dbi Yagi, A Lucent 10Db Omni, made with 16 phased folded dipoles, A tin can feed (featured on the this site), A double quad antenna (featured on this site).

Construction details of the Short Back-Fire antenna will appear soon on this site.


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