802.11b/g over coax

I want to put an antenna for my 802.11b/g AP about 40 metres away from
the AP itself. Questions:

Does coax exist for this application?
If yes, what's it called?
If no, what's the next best coax?
How much attenuation will I get?
Is it as simple as this, or is there something else I need to
consider?

The AP is a basic Linksys 802.11g AP/router plus a Linksys booster
unit, and I intend to build a yagi antenna so I can reach the spot I
want to be able to connect from.

Cheers,
Murray

That is way too far...your signal loss, in the coax, will be too much!

Consider running CAT-5 cable to your antenna's location, then mount the AP
in a weather proof enclosure, and a very short length of coax to the
antenna.

Bill Crocker


"Murray McCulloch" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> I want to put an antenna for my 802.11b/g AP about 40 metres away from
> the AP itself. Questions:
>
> Does coax exist for this application?
> If yes, what's it called?
> If no, what's the next best coax?
> How much attenuation will I get?
> Is it as simple as this, or is there something else I need to
> consider?
>
> The AP is a basic Linksys 802.11g AP/router plus a Linksys booster
> unit, and I intend to build a yagi antenna so I can reach the spot I
> want to be able to connect from.
>
> Cheers,
> Murray

Murray McCulloch wrote:

> I want to put an antenna for my 802.11b/g AP about 40 metres away from
> the AP itself. Questions:
>
> Does coax exist for this application?
> If yes, what's it called?
> If no, what's the next best coax?
> How much attenuation will I get?
> Is it as simple as this, or is there something else I need to
> consider?
>
> The AP is a basic Linksys 802.11g AP/router plus a Linksys booster
> unit, and I intend to build a yagi antenna so I can reach the spot I
> want to be able to connect from.
>
> Cheers,
> Murray

Bill is correct about running cat5 instead of coax would be better, but
if you still want to run coax you should at a minimum use LMR400, LMR600
would be better. Pain in the ass to work with and crimp connectors on,
but it works. www.electro-comm.com carries LMR.

"Murray McCulloch" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Thanks Bill and Roger.
>
> Looks like I'll have to go with plan B, which is as you suggested
> Bill. I couldn't afford to buy the coax that Roger mentioned anyway.
>
> Now here's a related question which is slightly off-topic, but maybe
> you guys will know the answer. If I mount the AP and booster with the
> antenna, I have the choice of running mains to it, or just running DC
> to it from the plug packs. If I remember correctly, I will lose less
> running AC than DC, but I'd rather run DC if possible because I can
> keep the box cooler if I don't put transformers in it. Will the DC
> power loss over about 30-40 metres of cable be detrimental? (There is
> no power available at the antenna so I will have to run it from the
> house)
>
> Cheers,
> Murray
>

Good question! If you run 'mains' to the enclosure, then you're set, but in
most U.S. municipalities this requires a permit and an electrician.

I don't know the current requirements of the booster, but you might have
problems running DC power over 40 meters of Ethernet cables using the unused
pairs (Power over Ethernet.) If you want to use DC, you still need to use
higher voltage (much higher) than the wall warts that come with the
equipment can provide and you must regulate the voltage at the equipment.
High efficiency switching regulators don't dissipate much heat, but they do
dissipate some. The bigger the power cable you use, the less problems
you'll experience, so try power over Ethernet and if it's not adequate, run
a seperate power cable. It seems you're on a budget, so here's a suggestion
that should work for you.

Go here: http://sales.goldmine-elec.com/prodinfo.asp?prodid=6377 and and buy
one. It's way over-kill, but it's only $10 and all you do is connect the
wires. While you're there, buy one each of these:
http://sales.goldmine-elec.com/prodinfo.asp?prodid=2978 ($4.95)
one of these:
http://sales.goldmine-elec.com/prodinfo.asp?prodid=6544 ($2.49)
and two of these:
http://sales.goldmine-elec.com/prodinfo.asp?prodid=5852 ($1.00 each)
(one for the injector end and one for the picker end.)
These parts can be used to build an injector supply. The injector supply
should be capable of about 48 volts DC at about 1 amp. If you choose the
do-it-yourself Power over Ethernet route, you still need to get the power on
and off the Ethernet cable. Do a Google search for Power over Ethernet and
you'll find some plans for that. Warning: the parts listed for the DIY
injector supply are just a collection of parts from a surplus site that look
like to me like they'll work. I haven't ordered these power supply parts or
built the power supply and the output voltage may be a little low.

Alternatively, you can purchase a 48 volt injector (BT-CAT5-P1-48) and
active picker (BT-CAT5-R1-05) here:
http://www.hyperlinktech.com/web/bt_cat5_r1.php

They show the injector is 15 Watts which is probably barely enough for your
AP and booster and they don't give any spec for the max current draw at the
picker. I believe these will be adequate for your needs and you can ask the
technician to verify when you place your order. Since the AP and booster
are likely to bring you close to the max on the commercial unit, I recommend
the do-it-yourself setup if you plan to power a fan in the enclosure. If
you do run a fan, plan the airflow inside the enclosure and use as small a
fan as you can find. Use the higher voltage (right off the Ethernet cable)
for powering the fan -- not the regulated 5 volts and if you use a fan,
better use a separate power cable instead of PoE.

If it's no problem to run 'mains' to the enclosure, then do it that way.
The wall warts don't generate a lot of heat and you'll have plenty of power
to run a fan.

Don W.

I got to thinking about the DC to DC converter for a power picker and a
couple notes are in order.

The converter I suggested is a 300 Watt converter. That's way more than you
need, but as I pointed out, the price is right for something to which you
only need to add a capacitor and a few jumper wires (the capacitor is
optional, but recommended.)

In case you use that device, here is a valuable document for you:
http://www.astec.com/reference/TRN/bm80.pdf

Pay attention to the sections on "Remote Sense" and "Enable Control" or you
will have no output. It's just a matter of connecting some wires.

This is a nifty converter and it's very efficient at converting voltages in
the range of 40 to 72 volts to a nice, regulated 5 VDC. If your booster and
AP require a total of 3 amps at 5 volts, that's 15 Watts. The converter is
only about 80% efficient, so the input should be 48 volts at about 20 Watts,
or well under half an amp. The converter will contribute about 1 Watt of
heat.

Don W.

"Don W." <(E-Mail Removed)> wrote in message
news:rfmcne4mws5YyI6iXTWc-(E-Mail Removed)...
>
> "Murray McCulloch" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed) om...
> > Thanks Bill and Roger.
> >
> > Looks like I'll have to go with plan B, which is as you suggested
> > Bill. I couldn't afford to buy the coax that Roger mentioned anyway.
> >
> > Now here's a related question which is slightly off-topic, but maybe
> > you guys will know the answer. If I mount the AP and booster with the
> > antenna, I have the choice of running mains to it, or just running DC
> > to it from the plug packs. If I remember correctly, I will lose less
> > running AC than DC, but I'd rather run DC if possible because I can
> > keep the box cooler if I don't put transformers in it. Will the DC
> > power loss over about 30-40 metres of cable be detrimental? (There is
> > no power available at the antenna so I will have to run it from the
> > house)
> >
> > Cheers,
> > Murray
> >
>
> Good question! If you run 'mains' to the enclosure, then you're set, but
in
> most U.S. municipalities this requires a permit and an electrician.
>
> I don't know the current requirements of the booster, but you might have
> problems running DC power over 40 meters of Ethernet cables using the
unused
> pairs (Power over Ethernet.) If you want to use DC, you still need to use
> higher voltage (much higher) than the wall warts that come with the
> equipment can provide and you must regulate the voltage at the equipment.
> High efficiency switching regulators don't dissipate much heat, but they
do
> dissipate some. The bigger the power cable you use, the less problems
> you'll experience, so try power over Ethernet and if it's not adequate,
run
> a seperate power cable. It seems you're on a budget, so here's a
suggestion
> that should work for you.
>
> Go here: http://sales.goldmine-elec.com/prodinfo.asp?prodid=6377 and and
buy
> one. It's way over-kill, but it's only $10 and all you do is connect the
> wires. While you're there, buy one each of these:
> http://sales.goldmine-elec.com/prodinfo.asp?prodid=2978 ($4.95)
> one of these:
> http://sales.goldmine-elec.com/prodinfo.asp?prodid=6544 ($2.49)
> and two of these:
> http://sales.goldmine-elec.com/prodinfo.asp?prodid=5852 ($1.00 each)
> (one for the injector end and one for the picker end.)
> These parts can be used to build an injector supply. The injector supply
> should be capable of about 48 volts DC at about 1 amp. If you choose the
> do-it-yourself Power over Ethernet route, you still need to get the power
on
> and off the Ethernet cable. Do a Google search for Power over Ethernet
and
> you'll find some plans for that. Warning: the parts listed for the DIY
> injector supply are just a collection of parts from a surplus site that
look
> like to me like they'll work. I haven't ordered these power supply parts
or
> built the power supply and the output voltage may be a little low.
>
> Alternatively, you can purchase a 48 volt injector (BT-CAT5-P1-48) and
> active picker (BT-CAT5-R1-05) here:
> http://www.hyperlinktech.com/web/bt_cat5_r1.php
>
> They show the injector is 15 Watts which is probably barely enough for
your
> AP and booster and they don't give any spec for the max current draw at
the
> picker. I believe these will be adequate for your needs and you can ask
the
> technician to verify when you place your order. Since the AP and booster
> are likely to bring you close to the max on the commercial unit, I
recommend
> the do-it-yourself setup if you plan to power a fan in the enclosure. If
> you do run a fan, plan the airflow inside the enclosure and use as small a
> fan as you can find. Use the higher voltage (right off the Ethernet
cable)
> for powering the fan -- not the regulated 5 volts and if you use a fan,
> better use a separate power cable instead of PoE.
>
> If it's no problem to run 'mains' to the enclosure, then do it that way.
> The wall warts don't generate a lot of heat and you'll have plenty of
power
> to run a fan.
>
> Don W.
>
>

Thanks for all your advice, Don. You've given me lots to think about.

Murray

"Don W." <(E-Mail Removed)> wrote in message news:<4sKcnWnmmrd_qI6iXTWc-(E-Mail Removed)>...
> > Bill is correct about running cat5 instead of coax would be better, but
> > if you still want to run coax you should at a minimum use LMR400, LMR600
> > would be better. Pain in the ass to work with and crimp connectors on,
> > but it works. www.electro-comm.com carries LMR.
> >
>
>
> Even with LMR600, the attenuation in 40 meters is 5.8 dB, so he'll end up
> coming out with about a quarter of the signal that he put in the other end.
> The price of the cable alone (without connectors or pigtails) will probably
> be in excess of $300 (without shipping or taxes.)
>
> In other words, it doesn't make sense to do it any other way than a
> weatherproof enclosure at the end of an ethernet cable. I'd also be a
> little concerned about PoE over that distance (and considering the current
> requirements of an AP plus a booster.) A passive injector/picker will NOT
> do the job! If he purchases a commercial, active PoE system, be sure to
> check the distance and current requirement against the PoE equipment specs.
> This is not an issue if there is 120 volt power available at the antenna
> location.
>
> Don W.

"Murray McCulloch" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) om...
> Thanks for all your advice, Don. You've given me lots to think about.
>
> Murray
>

If you try do-it-yourself PoE and need some (email) help, the mail server
part of my address is hotmail.com.

Don W.