Wifi range question

[Black_Ops]

hello all,

my friend needs me to network his junk yard with wifi so he can do inventory in the feild. the problem is that his building is metal concrete construction an well the ground is littered with tons of metal too, he currently has a linksys access point an a 12dbi onmi

with his 12dbi omni monunted on the roof he gets not signal gain on the ground, i moved the antenna to about 6' off the ground an we got about 300 feet of coverage, but thats only about 1/2 the area he needs.

i was going to run a dlink 700 AP on the other side of the building with another 12dbi antenna to cover the rest (runing a cat 5e run to the second AP)

what do you think of the plan? think it will work?

[Ddruid_SMP]

That will work, but the problem is that 12dbi omni. When dealing with Omni's, in general, the more gain the omni has, the 'flatter' the signal is. When you had the omni on the roof, the majority of the signal was shooting overhead, at 6' you are not going to get very far..

How big is the area he wishes to cover?

Take your time and look at radiation patterns, and draw out the area you wish to cover..

[Black_Ops]

3000 feet long 1500 deep generally, he was told by a tech that a 12 dbi is what he needed (its tat the end of 100 feet of low loss 400 cable 6 dbi loss), and he cant return the 12 dbi. whats the best way to make the most of it.

just looked up some radiation patterns, think i'm guna go with a 8 dbi for the second antenna, just gotta make the 12 work to its best first

[Ddruid_SMP]

I generally use 9dbi omni's on our towers, without an amp & at 100' up, I get about a 5mi radius. You may want to consider moving the ap closer to the antenna to shorten that length of LMR. I do not use more than 20' of LMR400, or 50' of LMR600, or 100' of 7/8" Heliax on any of our towers..
Most consumer grade ap's are 65-100mw (14-17dbm), for an AP I prefer a 200mw card (23db). That 6db loss is for an absolutely straight run of LMR any bends will also induce loss. I generally calculate LMR400 at .8db per 10', you also need to factor in the connectors at 1.5db each, have a small diameter pigtail? calculate .5db per 6", Lightning suppression at 2db, etc.

I would consider looking at using either a directional antenna or a sector, but that decission is up to you because a lot depends on the layout of the area needing to be covered.