KR1 with external antenna to cover a 20 acre ranch

polopaul

I need to cover a 20 acre ranch with the router output. I can mount the antenna on the eve of my house that is on a hill, in the center of the property, about 50 feet above the rest of the place. The antenna would be above the trees. Cable length from KP1 to antenna about 15 feet. Can anyone recommend an external antenna and cable combination to use with the KP1? Pigtail to cable to keep the cable weight off the SMA connector?

Thanks
Paul

MaximumSignal

xenophon · EVDO Addict Joined: 30 Aug 2005 Posts: 2004

You'd had have to use WiFi repeaters... a bunch of them.

polopaul · Posted: Wed Feb 15, 2006 6:09 pm Post subject:

I just need approximately 1000 feet in each direction from the house, which is near the center of the property.

horsessmellfunny · Posted: Wed Feb 15, 2006 6:11 pm Post subject:

two ir three Pre-N routers Smile

Or, a cantena, or do what I did. Use a satellite dish and a cantenna. I live on 40 acres, I had a 40 degree angle from the dish with access. With direct line of a sight, a good mile. 40 acres is 1 mile totally around. So you should be good! Google search will bring upon the best results.

MaximumSignal · Posted: Wed Feb 15, 2006 6:11 pm Post subject:

Scott · Posted: Wed Feb 15, 2006 9:46 pm Post subject:

20 acres? No problem. I've created ranch systems servicing that size and much larger (in one instance our WISP service was delivered through an 8 mile 802.11b feed).

The hard part here will be retaining good WiFi in close proximity to the KR1. It is a little tricky trying to do both close and far with the same radio. When you go "big" like this, you also must take into account the service environment. Some areas have a lot of ISM RF noise and channel use to contend with. Out in the boonies, not so much.

No, you can't just use the KR1 on its own, obviously. You will have to boost the WiFi output using a combination of external 2.4GHz antenna(s) and even possibly an amp. Having antenna height over trees and foliage is important as well (though depending on density you can push through it with power and polarization up to a point or even use a 2.4Ghz-900Mhz up/down converter at each end (a pain for mobile clients though). Another factor is if you're trying to push through a metal tractor cockpit or shop/storage shed you'll need an external antenna on the client end to keep the link solid.

For a non-amplified system, you might look into something like this...

Swap the KR1's antenna feed internally so that the RP-SMA bulkhead connector is fed from 'MAIN'. You could experiment using the on-board antenna connected to AUX, running it disconnected, or even possibly connecting another bulkhead connector for the small included rubber ducky antenna. It could work better the other way around: big omni on AUX, near-field antenna on MAIN. You have to experiment when you start using different antennas.

Honestly, I have yet to experiment with swapping the KR1's antenna feeds, yet I have plenty of experience using similar miniPCI radio cards. That is a standard thing for outdoor repeaters, etc.

As for antenna feeds and mounting: use a a short (6-12") LMR 100a RP-SMA Male to N-Male pigtail cable connected to the appropriate length of LMR 400 coax cable (N-Female to N-Male), and then a nicely powerful outdoor omni with an N-Female cable mount.

The tough thing is getting enough height to get over trees and foliage for the longer throw AND still have decent coverage in the near-field. Part of the problem is that increasing power tends to blow the signal straight out from the antenna sideways.

What you're looking for here is enough downward tilt (the ability to broadcast and receive below the plane that the antenna is on) matched with the right height for long-throw coverage. Plus you're trying to keep coverage in the near field with the onboard antenna if possible.

Depending on the topography of the proposed service area you may or may not have Fresnel zone issues. The overall diameter of the rise that your house is on and its height in relation to the rest of the area may help reduce ground reflections just by its nature. Raising the the antenna height with a mast could help as well. (nice Fresnel-zone calculator here)

Building a system with an amp requires a little more planning and a lot more money.

If you need more power, there are a variety of quarter watt on up 2.4GHz amps for sale. They seem to be getting cleaner and cleaner. Used to be that you started low and worked up in power due to cost and that the more powerful amps tended to boost a lot of noise too. I still like to size to need, rather than blowing power senselessly. The key here is using an inline design that allows the amp to be placed near the antenna which helps to keep your signal to noise ratio high.

There is also the issue of lightning surges and strikes. I always try to build outdoor systems with grounding and lightning suppression. Having lost expensive gear, I've learned my lesson. That and I don't want to watch a client's million dollar plus ranch house burn to the ground cause the antenna I stuck on his roof took a direct strike and ignited an attic fire. (no fires yet, knock on wood)

Still, I have friends and colleagues that have "grinned and bared it" without grounding and lightning suppressors and so far have lived to tell the tell. I suppose there are more dangerous areas of the country (and elevations) where not building in lightning protection is just plain dumb. Somis isn't too bad (I have had family living around that area for the last fifty years... Saticoy specifically).

One of the best resources I have found for 802.11b do-it-yourselfers is www.fab-corp.com. They can pre-build for you a ready-to-install system sized to your needs, or sell you all the bits to do your own system. They will crimp cables to suit, etc...

Start with just some good cable and a good outdoor omni (perhaps starting with the 9dB 7-degree down tilt or higher power) and see how far it gets you. If it looks like a go, lock it down and add all the safety elements it will need to be a good investment. As I said, its pretty tough to get a radio (even with MAIN & AUX connections) to adequately cover near-field on out to a larger service radius, even as much as things may be in your favor.

Worse-case, using the KR1's WiFi radio and antennas in the stock configuration along with another simple access point attached to the high power omni on your roof's eve for the long throw would get you pretty close if the KR1 fails to handle it completely.

The other AP could easily attach to the KR1's switch, so DHCP would pass right on out through. You could use either end of the ISM band for channel clearance between the KR1's WiFi radio and the other AP's radio (1 & 11, for the states), use the same SSID (network name) for easy roaming. Physically locate the KR1 directly below the omni if possible to take advantage of the the normally attenuated coverage pattern (below and somewhat directly above with an omni). It would be quite easy to power either or both over ethernet (POE), thereby shortening the needed coax and reducing cable loss. There's also poll mounting, but that starts to really add to the cost.

Whew... THAT was long, sorry. Hope some of it helps!

[Edit: rather than use LMR 100a off the RP-SMA bulkhead connector, consider the larger gauge LMR 250.

Or it may make more sense to take the signal right off the miniPCI radio card with a short U.FL to N-Male pigtail. Wouldn't have to mount another bulkhead connector... just a small hole in the KR1's case and a makeshift rubber strain relief to keep any pulling/twisting off the U.FL connection.

Any way you can reduce or eliminate connectors and small cable the better.]

brendanhoar · EVDO Heavy User Joined: 09 Jun 2005 Posts: 140

aintigreat · EVDO Fledgling Joined: 30 Jan 2006 Posts: 20

MaximumSignal

polopaul · Posted: Thu Feb 16, 2006 12:55 pm Post subject:

I didn't plan on using the EVDO router output un-aided without some external high gain omni antenna/cable and amplifier(?) combo. I was looking for some recommendations for a good possible antenna/cable/amplifier(?) combination.

brendanhoar · EVDO Heavy User Joined: 09 Jun 2005 Posts: 140

My suggestion would be to go to the Antenna Talk subforum of the http://sveasoft.com Forums. The only caveat is that the external antenna connector on the KR1 is of a different type than the WRTs, so any recommendations there would have to be slightly modified.

Specifically: http://www.sveasoft.com/modules/phpBB2/viewforum.php?f=18

I believe you have to register to get access to the forums, but you don't have to pay the yearly firmware fee.

If you do find some good recommendations, I'd love to hear about what you found.

-brendan

MaximumSignal · Posted: Thu Feb 16, 2006 1:04 pm Post subject:

Scott · Posted: Thu Feb 16, 2006 6:27 pm Post subject:

I'm up for speculation, math, theory, etc. There also is experience. I have used cheap off-the-shelf WiFI routers successfully in large outdoor areas very similar to polopaul's (ranches, farms, rock works, etc).

With the correct cabling and antennas, you would be surprised how reliable 802.11b private outdoor networks can be. That's not to say there isn't RF weirdness, latency, and plenty of experimenting. There is.

Of course this seems greatly similar to what we're all doing with EVDO and EDGE/GPRS...adding antennas and amplifiers and that is a PAID service feed that we cannot control. Difference here is that with WiFi we control both ends. I don't hear anyone claiming that EVDO cards aren't designed for the uses we're selling antennas and ampliers for, do I? Boosting and directing gain on a 20mW 2.4Ghz radio isn't all that different.

Hacked firmware (OpenWRT, HyperWRT, DD-wrt... Sveasoft) can help to squeeze the last drops of power from the radio on a stock "WRT" (Linksys). Not the cleanest route since you tend to spray hash on either side of your operating frequencies. 200mW miniPCI replacement cards work better, but then you're getting in the same ballpark cost as amps (which don't require firmware support and can be placed closer to antennas).

Single radio WDS can work so-so outside. Multi-radio makes more sense, but then we're heading back up in costs. An outdoor mesh/WDS network needs power and enviromental housings for each repeater. If we're talking ranch or farm fields, where will that power come from on the cheap out in a pasture?

polopaul · Posted: Fri Feb 17, 2006 8:29 am Post subject:

I stuck some numbers into a coax line-loss/gain equation that someone in a previous response gave me. With 32+/-2 mW from the router into 15 feet of LMR-400 and with a 15dbi antenna, I got 800 mW. That seems quite high.The equation asked for an antenna dbM value but the specs said it had a 15dbi gain. Is that the same thing? Cable loss with 100 feet of LMR-400 is only 6.798 dbm but I'm figuring on only needing 15 feet. I also found a 15dbi gain antenna with a low angle radiating pattern. I'll probably add in a paigtail to take the strain from the cable off of the router which will add a slight loss to the output.