This may belong in another forum, but increasing the range of your communications devices does have survival implications. Found these while browsing the news outlets over coffee:

Tactical Tech

Improvised wireless antennas

How to build a wireless antenna

Montenaro ... thanks. You're right - it does add to survival value.

I found myself wondering about improvised antennas for devices that rely upon GPS signals and satellite transmisions. In general, there are tons of GPS satellites in the sky. However, it could also be that your own GPS receiver is fading out and losing its detection capability.

More importantly for me personally, I use one of the SPOT2 satellite devices as a personal locator and signaller for emergencies. It's fine for many areas of the world. But SPOT satellites do not have complete global coverage, so the signal reception is sketchy in some locations. That includes places I visit (e.g. Africa). So ways of boosting signals is a good idea!

Pete #2

None of these style devices are going to help you with your SPOT. All require hook-up to the device and SPOT doesn't allow for that. The SPOT 2 has a pretty good GPS receiving antenna. As for transmissions, the issue for SPOT reception is a combination of satellite coverage by Globalstar and their earth station locations. Boosting the signal, even if possible, is not going to have much effect on that in most situations except with perhaps with a heavy overhead canopy. But that has a lot more to do with power than antenna design.

GPS antennas are a - well, rhymes with witch, because of the frequencies involved, and the EXTREMELY low signal levels involved, so the smallest mistakes can cause issues, along with the fact that you MUST pick up omnidirectionally

Tin Can waveguide antennas are pretty cool. If you need multi lobed or omnis - look into what are called "slotted waveguide" antennas for WiFi frequencies.

If you REALLY need range on a WiFi link - look into getting your ham radio license - remember that channels 1-6 are in the Ham radio band, and if you are willing to live with all that goes along with using it as a ham radio device (turn OFF all encryption, use your call sign as your access point ID, and set it to beacon, and NOT use commercial content, you can use part 97 rules - aka you can run a LOT (and I do mean a LOT - as in measured in watts, not milliwatts) more power to your antenna set (as in, with directional tests, one day a few of us were sending data 15 MILES - I don't think that anyone between our 2 points was probably able to use channel 5 during our tests however - and we made SURE no one could walk in front of either antenna)

Concur, but you don't need a lot of power to get wifi distance. With line of site, we got a 20 mile link running between a linksys AP and an orinoco PCMCIA card, each running about an unaltered 28mw, using 24dB gain antennas. We use this stuff to supply internet access to rest stops at a local bike ride, and never use power amps. We've done a reliable 8 mi link for the past several years this way.

To the OP, if you are really serious about this, pick up a copy of the ARRL handbook and some books on antenna theory from the ARRL store:

ARRL Store

And consider getting your ham license, as you can get seriously illegal very quickly experimenting with this stuff without one.

Doug - thanks for advice. At least I know what I'm up against. The people at SPOT made a few recent improvement (over last 2-3 years) that somewhat improved their satellite coverage in the marginal areas. Still, I wish they had 100% global coverage with good quality signals.

cheers,
Pete #2

Yeah, you don't

We were running crazy power as a test, more to see what we could do over the noise - we were running from a 'Tall building in Manhattan' (But NOT the empire state building) to a building on the Queens/Nassau border, as a test to see what could be done in disaster mode - we were on air at those kinds of power for circa 5 minutes. We found we could no it nicely with one of the readly available 'high power' PCMCIA WiFi card, and a GOOD antenna, IF we kept the coax run short (like a couple of feet). You know - the typical rules you play with with LNAs and the like. The High power test was a "can we hook the antenna on the far end of circa 100 ft of LMR-400 and still get signal in, in case we can't setup where we want"

Our eventual answer? A laptop, the high power card, and a router in an "orange box" - running in infrastructure mode - the Orange box goes in a high spot with a BIG battery powering the box, the laptop is basically acting as an internet router/gateway - and feeding the signal to the router, which is providing the local WiFi to the area. I don't know the exact way it was done, as one of the other AECs and the EC were the guys doing the main playing, but I know where the box IS, and how to set it up

Heh, yeah, you'd need that power in that environment. We did our test between the roof of a 16 story bldg, and a school yard playground set that had a favorable terrain profile. The next year, the company deployed wifi in the 16 story bldg, and we couldn't make the same link from half a mile away. I really didn't want to use a power amplifier because our company execs were in the top floor of that bldg, and I didn't want to have to explain to them why they couldn't get their wifi.

For the shorter 8 mile links we have a ham with a 70ft tower on one side of a lake, and the ground site about 15ft AGL, at the end of a tributary. Might not be able to make it work if we didn't just happen to have the favorable terrain.

It's funny - some hams are VERY wedded to "that's the way we've always done it". Out here in Queens (at least till the latest shift - not sure what is happening) - but for a decade our goal was

"Let's get the end user into a config where they don't know we're there, as fast as possible"

We spent a LOT of time on long distance WiFi (I was EC at the time, and delegated). We also spent a LOT, and I mean a LOT of time learning the ins and outs of the much dreaded Winlink2000. Yes, I know WLk2k is a pain on the HF bands, but it's NOT where we were putting our effort. We put our effort into using the existing VHF/UHF packet 'flexnet' backbone, where HF winlink was a deep fallback

We figured out how to configure winlink that it would use wired internet as a first choice, then the HighPower WiFi, then fall back to the packet, then finally to HF, and THAT was usualy via at least one hop on VHF (we have 2 fixed HF stations in the county, were they have generators, and VHF/UHF inbound nodes)

In addition, we have at least 2 portable voice repeaters ready to go (complete with cans)

We also have 4-5 VHF to internet gateways (PMBOs) within either direct, or 2 hops of everywhere in NYC, and obviously, with flexnet, we ccan route (in fact, we regularly tested a Long Island (eastern Nassau) to NY SEMO (Albany) pure RF packet link by at least 2 routes. We also have 3-4 spare digipeters for flexnet (and APRS) ready to go, and actually a spare PBX in one guys house.

In short, our main goal was to give our served users email back, at as high a baud rate as possible, as fast as possible, with voice as a nice 'tactical' adjunct

One of our served agency guys was one of the bigs in Salvation Army comms post Katrina, and he became a HUGE fan of Winlink - he knew about it from us, and made sure he grabbed the winlink guys from Texas. He said that was why THEY had communications and very few logistics issues compared to everyone else. The way he put it "the ability for the guys in the field to setup an excel spreadsheet with their needs, and email it to us 150-200 miles away, and for us to say 'OK - here is what is on what truck' made all the difference"

KG2V,

I just passed my technician exam last Wednesday. My first HT is due in tomorrow.

In the summer at my cottage I run a Wifi Mesh network using a pair of Linksys WRT54G routers running Talisman (like WRT-DD) software and a pair of 12 db corner antennas. I only need to go about a mile and it's over water. This winter I picked up a pair of Linksys wireless-N routers to see if I could increase reliability. The software allows me to pump up router power but I don't do it much as I do not want them to overheat.

I also just got an Alfa long range USB adapter for a laptop - some of these put out 2,000 mw and come with a 5 db antenna. I suspect this would work with just a laptop on a line of sight along the distances you are trying.

Since I am just a rank amateur radio novice I am trying to understand what your system does. How do HT's connect to it? Or why?