Quadrifilar antenna for video transmission usage?
For video transmission, looking at operation of less than 1000mW, at 11.1V
Video and regular FM transmission like communication with sensors.
Any information would be appreciated.
Some radio control pilots outfit their model airplanes with video cameras, then they
put up videos of flights. Some are on Youtube, some on individual websites. I don't know what percentage store footage in a memory card, and what percentage transmit video to ground.
I did that FPV, except and for circularly polarized video transmission we used antennas called skew planar and cloverleaf. I wanted to see if quadrifilar was superior. Guess I will have to test.
Quadrifilar is a good choice but might be big and fragile if you are using low frequencies. As it's likely the transmission path will vary in direction and azimuth, you want an antenna that is omnidirectional and works well at all angles above ground. The gain will be low but over short distances that probably isn't important. Patch antennas are another option but can be difficult to make and quite large at low frequencies. Cloverleaf is good at different directions but poor at high angles.
Brian.
I'm not sure if these are still considered low frequency but I have the options of: 900MHZ, 1.3GHz, 2.4GHZ, and 5.8 GHZ
The patch seems to be for long distance, linear polarity if I'm not mistaken, paired with a dipole antenna. The kind with two tips, one goes up, the other goes down.
I like the helical antenna, good long range. I saw a few people with tracking helical antenna ground stations.
Thanks for your response.
I would consider those to be high frequency in antenna terms. What I was warning about was if you were using low frequency, say 50MHz, the quadrifiar antenna would be about 9 feet high and 3 feet across! Given their fragile construction, you would need a scaffold frame to hold it together!
As the frequency increases, tha antenna size reduces and even at 900MHz, you could hold it in your hand quite easily. Their gain pattern is almost a dome over the center axis so they are ideal for picking up moving overhead objects. They are commonly used for GPS reception for example.
Brian.
I'm syked to hear that.
I am wondering if I could construct my own antenanna propagation box.
I would propose a slotted patch antenna with circular polarization, on both sides, avoiding in this way the H to V polarization mismatch.
http://cdn.intechopen.com/pdfs/14719.pdf