What kind of antena do I need for coverage of 500ft x 165ft flat area??
I am trying to set up a wifi hotspot that covers a campground.
The campground is a rectangle shape of about 150 meters (500ft) lenglth by 50 meters (165ft) width.
There are lots of trees, but there is a nice high pole almost directly in the middle of the campground, where I will mount an outdoor omni-directional antenna.
(I will put the router at the base of the pole.)
The problem is that I have idea what kind of antena is needed, so that the entire campground gets decent coverage. Does anyone have any recommendations? Please be as specific as possible, and include a link to product sales page, amazon/ebay or whatever, so that I can see exactly what is needed.
(I live in Europe, so once I know what is needed, then I'll try to find the same thing or similar over here...)
EDIT: I am using a Linksys WRT54GL v1.1 router. It has dual-antennas, but I will only connect one of them to the antenna on the pole. I will disconnect the other one.
The issue here is that whatever router you use that has the range (for example, an EnGenius ECB3500) is only half of the equation. Reaching out to remote sites also needs to be complimented by every remote router being powerful enough to reach back to the host router. In other words, you need to have more powerful routers everywhere in the net.
Antennas can be part of the solution but a sub 100mW router will struggle to reach back to the host at 500 feet even with a 8 or 12dBi antenna.
it's a two way radio. the other end of the link will include laptops. more power at the router will allow the laptops to see the router, but will not help the router see the weak transmitters on the laptops.
you need gain antennas. antenna gain works both ways, transmit and receive. I would use a downtilt gain antenna
I understand now that a higher dBi gain antenna means there is less vertical coverage "under" the antenna.
So in my case, if I mount the antenna on a 20ft (4m) pole and use an omni-directional antenna with say 12 dBi gain... it will result in a big "no coverage" spot under the antenna of about a 20 meter circle.
But in exchange, the coverage will be much further then if I used say a 5 dBi gain antenna (which would have almost total coverage under the antenna.
This is all very interesting, and very confusing.
Is there anywhere I can go to plug in the numbers of my router and antenna and see a visualization of what the coverage pattern would be, overlaid on a map showing distance?
Higher DBI antennas do not, everything else being equal, reduce coverage under the antenna. In fact coverage will improve in all directions. The vertical antenna radiation pattern is like a doughnut. Google it for a clearer image of the shape.
yes, there is coverage a hole under 12 dbi and higher gain omnis on a mast.
the gain in an omni antenna comes from compressing the RF energy vertically. the same energy goes into a 2.1 dbi antenna or a 15 dbi antenna. if you gain more energy somewhere ( horizontally ) you must lose it somewhere else ( vertically ). it's a law of physics thing
omni gain antennas are collinear arrays. maximum gain is 15 dbi until the laws of physics change. high gain creates a coverage hole under a mast mounted omni until the laws of physics change.
Thank you very much, Mark Oney, that was very helpful, and I think I now more clearly understand how the antenna patterns work.
One last question...
How can I measure "how far" a given router and antenna combination will work for? In other words, I need to try and determine if I need a 2 dbi antenna or a 5 dbi antenna or whatever. I would like to try and use the minimum necessary, so that I can minimize the "hole" under the pole where the antenna will be mounted.
Ok, thanks. Are all down-tilt (or omni or whatever) antennas basically the same, except for material and dbi?
In other words... is it best to always purchase the most 'powerful' (highest dBi) antena possible?
For example.. on the link you gave, there are two antennas. They seem identical except for dBi (and 1 degree downtilt). Should I just get the higher dBi one?