I had a 5.8ghz system (600 mw). i went to a 1.3ghz because 1) There is higher level gear available for that frequency 2) i was not pleased with the reception at all 3) at that high of a frequency the room for error when making your own antennas (cloverleaf and whatnot) is so small its almost impossible to get it right.
I am much happier with my new 1.3ghz system. Just my .02$
if you're using skewplaner and cloverleaf antennas its not multipathing you are suffering from when you go over the antenna. If you havnt already, that video that david did on different antennas will explain why it isnt. Anyways, you are instead suffering from the top of the antenna being the weaker part of the signal, although the cloverleaves have very little gain so its almost a perfect circle of signal
I spoke with some of the guys from my base about this vary topic. I am a member the Air Force 193d Special Operations Wing that specializes in Audio/Video transmission and receiving. We have lots experience with audio/video transmissions. Here is what they told me as a guideline to make basic decisions by...
-First, they said think of the chosen frequency like the frequency of the music in a car stereo when considering range and flying around objects. Like in the car stereo where low bass music seems to go through just about anything and go on and on, so does the lower video tx waves. The lower the freq, the more "blunt force" the waves seem to have at pushing further and further.
-Second, they said there is something else to consider, though, with regard to the size of the information going across the waves. The higher the frequency being transmitted, the more information seems to flow. This is in reference to higher definition video (which most people seem to strive for). Simply put, higher lines of video definition logically will transmit better on a higher tx frequency than a lower frequency.
So, it's a bit of a challenge for the beginner to determine what purchases to make the first time around. As for myself, I want the best definition I can get for my budget. However, I also want the range of the system to be as good as my Spektrum TX & Rcvr.
The other nice tidbit of information they gave me was that Transmitter strength (often measured in watts) is NOT directly proportional to range. For example, just because a 200mw system can effectively transmit one mile does not mean a 400mw system can transmit 2 miles. It will be less. They said their is a math formula to determine the effective range with regard to the power, but I wasn't about to work through that headache quite yet. For me to keep it simple for myself, I just say buy the strongest quality Tx that you can afford and works for your application.
Last, they have a device that is too cool for tuning an antenna. It looked like a large oscilloscope. They were showing me how they can first fine tune the circuits of the Tx and the Rcvr to be more fine tuned which will drastically increase their performance and quality of signal. Then they used this cool device to precisely measure the frequency the Tx is sending and then use the device to see how well the antenna is tuned. With that information, they could adjust the antenna down to a very precise fit for the frequency which helps get the best possible scenario. I love this stuff! (if only I knew how to do it myself!)
I'm not trying to jump in here sounding like I know everything about this topic, because I will be the first to say I am a newby, I just want to share a great resource that I believe we can use to help solve problems and answer questions!
And that is what this site is about! Thanks for the info SuperJon. That made more sense than all the threads on this subject put
I am just about to pull the trigger on my first attempt to get into this but REALLY don't want
to spend $400.00 plus for an experiment. The thing that concerns me about 5.8 is upgrading to better
antenaes that are too small to accurately produce myself to get decent range.
I use 5.8GHz for my video and I've made my own clover leafs and Skew Planar Wheel antennas. Trust me, the difference in video transmission quality when using home made antennas compared to the often rather crappy standard 2dB dipole antennas is totally worth the hassle of making them yourself. The thing is, the standard antennas are not made for a specific frequency as yours will be. So, even if you actually miss your frequency by a bit your antennas will still most likely be better than the standard ones. Further, they will be circular polarized as opposed to the linear polarized default antennas and circular polarized antennas are better suited for 5.8GHz than linear polarized antennas are.
It isn't really that tricky. Just follow IBcrazy's guides on RCGroups and You'll be good to go. Oh, you might want to measure twice, though since the tolerances are on the small side when making your 5.8GHz antennas. Other than that, It's really just the same as making bigger antennas.
Try making your own and I bet You'll be happy with the result. Good luck!
ananas1301 thats a pretty great tool.
Heres the thing with 5.8ghz that few of us like to truly admit.
The reason we are all drawn to it when we first get into fpv, is because we all have 2.4ghz radios that we love, that we want to keep using. I really haven't found another reason to use it.
I started out with it. I found it was dangerous until I started using CP antennas because of how it would drop out.
here is a video I made that shows this http://www.youtube.com/watch?v=zI9AiI3OFco
Even after CP I wasnt getting the range I needed. About 375 Meters was all that was reliable. When you hit the end of that useful range the video drops out FAST. It is affected alot by trees or anything else.
Of course as a newb you really shouldn't by flying further than that to start but I founf it very limiting. I eventually sucked it up and bought a used JR 72mhz radio. I bought a lawmate 2.4ghz 500mw transmitter and the 2.4ghz reciever card for my Dominators to try it out.
Just doing that almost doubled my useful range with much better reliability, and I was using a ground station with my 5.8ghz.
Now with my immersionrc Duo 24 with a 14db patch/wip and a 600mw immersionrc transmitter I fly out at 3000meters with no issue.
2.4 has worked for me. I like it because I find it reliable, small, I get great distance without too much power, and it is fairly modern and plug and play.
I can't really knock 1.2 1.3 or 900mhz either although the cp antennas for these frequencies get kind of large and fragile.
The $62.00 experiment has been ordered! In the meantime I will make a platform for mounting and
try my hand at making some antenae.
Years and years ago I used a SWR meter to match antenaes on CB radios.
Can I use the same type of meter to dial in 5.8 ?