wireless router as Lan adapter
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Posted by Jeff Liebermann on July 4, 2008, 8:41 pm
Please log in for more thread options That depends on how much cable and how much fade margin you have. I prefer to put the router next to the antenna, but even that requires a coax "pigtail". The question is how much additional cable loss you can tolerate before your signal craps out. There's a really crude test that might offer a clue. Take a piece of wet cardboard or black IC foam to block half your panel or dish antenna. That's a 3dB loss. Block off 3/4 of the panel, and you have a 6dB loss. Crude, but effective. Don't use foil or metal reflectors for this. You want the blocking device to be an absorber, not a reflector. That should give you a clue as to how much loss you can tolerate. Of course, a real coax RF attenuator is the right way, but if you had one, you probably wouldn't be asking this question. Cable loss is easy and comes from a simple chart: LMR-200 16.9 dB/100ft LMR-240 12.9 dB/100ft LMR-400 6.8 dB/100ft So, if you decide that you can tolerate 3dB of additional cable loss, that means you can use about 44ft of LMR-400, or 23ft of LMR-240, or 17ft of LMR-200. Lots of pre-cut cables with connectors available: <http://www.fab-corp.com/home.php?cat=248>
<http://www.fab-corp.com/home.php?cat=249> What this means is that for fairly short coax runs of perhaps 10ft or less, don't worry about cable type. Almost anything will work. If a few dB make a difference, you already have a marginal system anyway and need to do something else. Also, I've been quite successful using 75 ohm coax instead of 50 ohm as in RG-9/u CATV coax. There's a slight mismatch, and two additional coax adapter are required. The nice part is that it's commonly available, very cheap, and can be assembled without expensive tools and crimp connectors. However, don't go cheap on the F connectors. Use proper piston type tools and "push on" F connectors. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 | ||||||||||||||||||||||
>the losses in the cable. At 2.4Ghz its going to take some really good
>feedline. How do the WIFI people handle this? I would think about
>putting a router very close to the antenna since low loss cable can
>cost bucks a foot.