WRT54G and 20 dbi yagi

Depends on where you are (what the weather is around there, and what it may do to signal strength). For long links, I've gone highly directional yagis, but only in places that don't have much bad weather. For those I do a combo of increasing the signal strengh, and yagi's (but not quite as strong needed).

for that specific device (wrt54g), check out the firmware upgrade from SveaSoft at -

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power is 28mw, but the Svea firmware will let you boost that up to

251mw. The higher power goes thru stuff like fog/rain/snow etc, better than a longer antenna, and costs about the same (ie firmware upgrade costs about the same as a more powerful antenna).

There are also "booster/repeater/amps" (like the cell phone repeaters)... Connect to the back of the AP, and give large amounts of output power (100mw - 3w) for a very tight beam (they may be technically illegal, depending on the power output, and your country/location), I'm just mentioning that it is "theoretically" possible if someone wanted to do it)

Reply to
Peter Pan
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im trying to reach the ap that 5 kilometers far from me...i have wrt54g

in client mode attached to the roof with weatherproof box and i can see

the ap...has anyone suggest antenna??...im planning to buy 20 dbi

planet yagi...

Reply to

Ummm... I beg to differ. Last time I checked, dB's of antenna gain are the same as dB's of power gain. Going from 28mw to 251mw is a

9.5dB increase. That's better than an 8dBi single patch antenna, but not as good as panels or dishes that go up to about 24dBi gain.

In addition, cranking up the tx power only increases the gain in one direction. If you're talking to an identical high power unit in a point to point bridge arrangement, increased tx power is a good idea. However, if you're setting up an access point, and talking to the typical +15dBm (32mw) laptop client, all the tx power in the world isn't going to improve communications if the access point can't hear the laptop clients. (This is why I detest high power radios used in mesh networks). On the other foot, an increase in antenna gain improves the situation in both transmit and receive.

Incidentally, the maximum legal tx power in the US is 1 watt (+30dBm) into a +6dBi antenna. It's not terribly clear in 15.247, but that means 1 watt no matter what type of antenna or service you're using.

As for higher tx power going through fog/rain/snow better than a longer antenna, methinks you're correct for only a limited subset of conditions. Fog/rain/snow/ice/bird_dropping will detune an antenna. Water incursion into the antenna or coax will cause signal loss. In general, the simpler antennas tend to be less sensitive to water related problems than the more complex high gain antennas.

Reply to
Jeff Liebermann

While that is true in ideal conditions, one of the first q's I asked was where he was. For instance, in the Pacific Northwest with lot's of precip, bumping up the power seems to work better (along with a moderate antenna), but in the deserts of nevada, you don't get a lot of rain to scatter the signal, and it doesn't really matter, just high gain antennas seem to work okay. As for his specific application, he just basically wants to bridge two ap's, but didn't say where he was.

Thanks for the 1 watt power limit in the US, my supplier has a 1w/2w/3w

802.11 repeater/boosters, good to know the 1w (for $149) is reasonable for use in the US, gives me an idea for bridging to a second site 10km away. Any info on solar powered repeaters? Seems to work for cell and amatuer radio stuff.
Reply to
Peter Pan

Within most countries, it actually a boat supplier, and are *supposed* to only be for offshore use.

Sounds like what I need for a client. A few people living in a valley, with no wifi, but they have cable internet in the town on the other side of the mountains. Sounds like a solar power repeater on the ridge, may be just the thing..

Reply to
Peter Pan

In my limited experience in the deep dark wet forests of the Santa Cruz mountains, rain scatter is not a problem at 2.4GHz. I have links that I monitor continuously (using MRTG and SNMP). For quite a while, I was mystified by how the signal strength would not vary in the slightest during a big rain, but 2 days later, drop anywhere from 3 to

10dB. It would then take a day or two to recover. No rain in sight meanwhile.

Note that I said 2 days later, not the next day. It took a while to figure out what was happening. The rain would usually appear in the evenings. Everything would get soaked but would be mostly waterproof. The next day, the sun would appear and raise the air pressure inside the coax cables. At night, the temperature would drop, causing the air pressure inside the coax cable to drop, which would suck in a few drops of water through my alleged waterproof seals. This usually would not cause any problems until the heat of the sun caused the water to evaporate. High humidity water inside an air dielectric coax was as a good as a short circuit. Anyway, it wasn't the rain drops in the path that was causing the water problem. I suppose it's worse in the Pacific Northwest, with more fog/rain/moisture, with the added complication of freezing.

Another water related headache is water condensing on circuit boards. When the temperature hits the dew point, everything gets soaked. The heat from the boards will usually prevent this problem. However, really low power devices don't generate enough heat to totally prevent condensation (or freezing). The easiest fix is to mount the boards vertically, so they drain. Otherwise a spray wax or urathane conformal coating will really help. However, that doesn't work with connectors that tend to trap water.

Anyways, it's not atmospheric precipitation attentuation that causes problems. See bottom of:

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2.4Ghz 0.08dB/mile for a torrential rain is nothing.

3 watts? Kinda illegal except for ham radio use.

Yeah. I've built three solar AP's and one repeater. The first used a DC-DC converter to supply power from a pile of gel cells. Morningstar charge controller. Then I discovered that the WAP54G family will run on any voltage between about 4VDC and 15VDC. So, I just hung it across a 12V battery, charged it with another charger controller, and discarded the DC-DC converter. The calcs are fairly simple. Look up the insolation values for your area. Calculate your power drain requirements, which will size your battery, charge controller, and solar array. It's not much to see, but I can post photos when I find them. (Hint: if you've read my stuff, you'll probably have noticed that I don't think very highly of repeaters, mesh networks, and overpowered transmitters).

Reply to
Jeff Liebermann

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