Discussions

Extending range of rc and video links

Posted by Joel Ryan on February 6, 2010 at 3:10pm
I know a lot of us try to extend the range of our links with better antennas, more power, etc., but why not try to extend the range by putting our antennas up higher?

(please excuse my horrible artwork :P I'm not much of an artist, but I think it gets my point across)


Normally we have a setup similar to the right of the picture, with an antenna broadcasting from the ground, possibly on a tripod or the roof of a car to give it better LOS. Why not suspend an antenna from a helium balloon? This would only work with omnidirectional antennas, unless you were to devise some way to aim a directional antenna, but a medium sized balloon could probably hoist the antenna, along with the cable required? right?


what do you think?

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Replies

  • Robert Palmore March 8, 2010 at 6:31pm
    Joel,
    I'm new to the civilian world of drones but have a good number of years experience in the Air Force plus had my ham radio license when I was 17 and have build an untold number of antenna one of which was used for remote controlling AQM 34 drone of Point Magoo Naval Air Station. With that background I still am not sure my idea is a good one due to the lower range of transmitter frequency. Lower the frequency the longer the antenna. Here is a link for making what is called a collinear antenna.
    http://www.dxzone.com/cgi-bin/dir/jump2.cgi?ID=15184
    As you can see it rapidly becomes longer and longer. It is possible to stack several of these flattening the doughnut radiation pattern around your antenna flatter and flatter. What would be a more practical idea but still cumbersome at these frequencies is a yagi antenna.
    http://www.skyscan.ca/Antennas.htm
    You would have to tripod mount the antenna or have some one to hold the boom of the antenna so to point it at the plane.
    Both of these ideas I don't think very well of but they are along the lines of your original quest. I wouldn't suggest the balloon or mast idea. The signal loss along your coax cable would surely consume any advantages you might gain. plus one really big reason not to go this rout is radio waves are line of sight and unless you intend to fly very low at these long ranges, you really don't gain any signal strength by just being higher.
    Now that I've prattled on a bit and wasted every one's time here is what you really need if you want REAL RANGE.
    http://www.webx.dk/rc/uhf-link3/uhf-link3.htm
    This is the guy that really can speak from experience. I bow to his hands on experience and having actually produced exactly what your needing. Hope folks are ok with on the other junk.
    Love and peace, Robert.
  • Moderator
    Brian February 7, 2010 at 10:51pm
    When I first started in the military we had a backup emergency transmitter for CW. It had a wind up crank and a LONG wire which was lofted by a large box kite. A second operator would tap out a message using morse code. It was fun to practice with, but glad we didn't NEED to use it.

    I thought about a communications relay teathered blimp for SAR along the same concept. Due to hills and obtructions on the ground a teathered balloon can go above and relay LOS signals from the dark side of an obstruction to others who otherwise would not recieve their call. I considered the same approach for RC and a video link back, but long distance video really comes back to just using the right antenna for the job.

    A properly tuned patch antenna will increase your distance greatly and you don't need a bucket full of cement or large balloons...
  • Tim McMahan February 7, 2010 at 11:51am
    That should work great, but yeah, there are simpler methods that might be more feasible. The most common is some sort of telescoping pole, mounted in a 5 gallon bucket filled with cement. You can also get fancy and put carry handles into the cement before it sets up. Then you can also add guy-wires via utility line and tent stakes. That's how my portable HAM mast is set up anyway. :)

    KCØYOL
    Tim
  • Admin
    Morli February 6, 2010 at 3:53pm
    Yep , that will work too if low loss cable is used , infact such contraptions are used amateur radio. You may want to add inline amp also. But wind will keep the balloon pushed down wind or swing around which could be trouble. Why not use a tripod or even use simple fishing rod( 3-5 mt long) with antenna mounted on the top. Just anchor it or dig it in.
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