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Yagi's are simple to make, it's dishes that are VERY difficult, it's hard to make an accurate parabolic dish - and they need to be accurate to work correctly.
Yagi's are simple to make, it's dishes that are VERY difficult, it's hard to make an accurate parabolic dish - and they need to be accurate to work correctly.
no one makes dishes for home use, they go buy one at a ham club etc swap meet for a couple of bucks, you get used ones from satellite TV installers likewise for virtually giveaway.
Its then just a matter of mounting an antenna for the freq you wish to use at the feedpoint.
There is plently of info online and in various amateur radio and other publications for antenna construction to suit a dish feed
MUCH MUCH easier than building a hi gain yagi and will give higher gain much easier, a 700 - 900 mm dish will give ~ 22dBi gain at 2.4GHz
I used to have a book about Aerials, it was far too complicated for me to even read.
As I have said, I did once make a yagi (Wifi), it was for this sort of thing. And I take the point that dishes are difficult, I know they are not simply a bowl. As suggested I would buy the dish and mount various aerial fittings, as seen on 'the web'. I also understand that the more range the pickup aerial the more accurate it needs to be aimed, which would not be easy.
Can someone make it clear, which is best Transmitter/receiver cctv, as in Helicopters etc or Wifi, or are they both the same in respect of signal success, apart from the boxes at each end.
Nigel, you don't need to make one, you can just use old satellite dishes. There are many links to people that have done this using Wifi . I believe the current world record for wifi distance (line of site) is 125 miles, and all they did is use an old 8 foot satellite dish.
Camerart, you can find instruction tutorails and schematics for wifi cantenna's yagi's and biquads, all are quiet simple to make for wifi frequencies.
I still say you should be able to find a commercial 900mhz off the shelf setup that will do video at respectable distances. Making a directional antenna for 900mhz is going to be considerably more difficult simply due to the increased size.
This has already been explained, the higher frequency means it has more problems with physical objects. The link you provided showed a 1.2ghz product, better than a wifi signal because those are double the frequency.
I'd look for a 900mhz product if you can find it. The 1.2ghz product may work.
This has already been explained, the higher frequency means it has more problems with physical objects. The link you provided showed a 1.2ghz product, better than a wifi signal because those are double the frequency.
I'd look for a 900mhz product if you can find it. The 1.2ghz product may work.
I believe I quite clearly stated that the lower the frequency the less obstacles have a part to play, however if you're using directional antenna that this compounds the issues regardless of frequency as reflections no longer can take a part in primary reception.
The range of reception generally speaking is related to an isotropic antenna something like a whip/dipole setup, meaning 0-3db of gain. Directional antennas when a frequency is low are relatively large given lower frequencies.
I believe I quite clearly stated that the lower the frequency the less obstacles have a part to play, however if you're using directional antenna that this compounds the issues regardless of frequency as reflections no longer can take a part in primary reception.
The range of reception generally speaking is related to an isotropic antenna something like a whip/dipole setup, meaning 0-3db of gain. Directional antennas when a frequency is low are relatively large given lower frequencies.
Yes, you did say that. This is why I sent the link with 900Mhz, from your suggestion, to see if this is what you were talking about. I'm not sure 900mhz is legal though.
Go easy on me, I'm not as technical as you are, I had to refresh what isotropic antenna and the significance of DB in your answers was.
900MHz is only allowed in North & South America and Australia, its generally not allowed in the rest of the world. In the UK 900MHz is generally used for GSM (not just publicly available GSM) and MOD as well as others.
900MHz is only allowed in North & South America and Australia, its generally not allowed in the rest of the world. In the UK 900MHz is generally used for GSM (not just publicly available GSM) and MOD as well as others.
I was going to double check the 1.2GHz band, when I found this web page which sums up the UK situation very well.
Check out all the FAQ on this page, they don't too speak well about the license free 1394MHz frequency and seem to favour the 2.4GHz band.
To use 1.2GHz you would need an amateur license, but the equipment may be easier to find.
I was going to double check the 1.2GHz band, when I found this web page which sums up the UK situation very well.
Check out all the FAQ on this page, they don't too speak well about the license free 1394MHz frequency and seem to favour the 2.4GHz band.
To use 1.2GHz you would need an amateur license, but the equipment may be easier to find.
This is a very helpful site. Assuming their FAQ are true, it seems that buying from unknown sources can be a minefield, with very variable results.
I could probably use the 1.2Ghz, with a licence, but they didn't recommend it, because of it being older technology (filters etc). I think this will change later on.
It is quite likely that I might buy their 2.4Ghz 100Mw set-up as this seems proven. They don't appear overly expensive, bearing in mind most of the alternatives need to come through customs, and could have extra charges to the prices advertised, or even confiscated at Customs.
I assume that as 2.4Ghz is also the Wifi range, this will lend itself to the Wifi aerials talked about earlier.
I think the Customs issue is over egged, you can import equipment than runs on any frequency (legal or illegal) its only when the end user trys to use it, that it becomes a problem. Thats why there is so much junk being sold on E*ay that is illegal to operate in this country, mobile phone enhancers, cordless phones using the wrong frequency, GPS & GSM blockers, etc.
2.4GHz will be limited to line of sight for any decent distance, remember that a receive antenna high up off the ground will give better results.
If you were to use WiFi cameras and technology you would be able to use some routers and access points as a hop site, which if installed in a tree for example would give you a greater transmit distance. For example ground buggy to tree (short range) then tree to house (long range).
2.4Ghz camera systems may also be able to receve and retransmit via a hop, but I haven't seen any as of yet.
I think the Customs issue is over egged, you can import equipment than runs on any frequency (legal or illegal) its only when the end user trys to use it, that it becomes a problem. Thats why there is so much junk being sold on E*ay that is illegal to operate in this country, mobile phone enhancers, cordless phones using the wrong frequency, GPS & GSM blockers, etc.
2.4GHz will be limited to line of sight for any decent distance, remember that a receive antenna high up off the ground will give better results.
If you were to use WiFi cameras and technology you would be able to use some routers and access points as a hop site, which if installed in a tree for example would give you a greater transmit distance. For example ground buggy to tree (short range) then tree to house (long range).
2.4Ghz camera systems may also be able to receve and retransmit via a hop, but I haven't seen any as of yet.
I don't have high expectations of the results, but if it helps a bit then all well and good.
Each situation is different, and for example an animal might not want to walk near the tree with the relay in it, but it might. I even thought about a second Radio control buggy as Relay. I'm not trying to make extra work though. Remember every extra bit means more batteries and equipment to fail, so less is more sometimes.
I chose 2.4Ghz, one reason is because of the many experimental aerials I've seen in this frequency also even though lower frequencies might give better results in theory, the 2.4 range could be more stable as this frequency seems to have been honed more than the others over the years. Also I might be able to transmit legally, which is worth aiming for.
I have a few doubts about buying from an unknown source, and the guy from FPV seemed to know his stuff.
If anyone's interested, I'll report back with test results.
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