Dipole on a wing

[bigMouse]

Just wondering about mounting on a flying wing, Any ideas?
Current thinking is to use a stiff vertical element on top with the lower element trailing.

[Dusty]

or have it flat on the underside of your wing, then change the orientation of your transmitting antenna to horizontal

[MrBen]

thats what I intend to do bigMouse, Im just using a 'Sander' style whip at the moment but I want to change to a dipole for more range. Does anyone know a good guide to make a dipole UHF antenna?

[papa_lazerous]

A trailing gnd wire won't make for an efficient antenna, I've just made a new dipole for my wing. Gimme a day or two and I'll post a guide on how to make it and fit it

Sent from my GT-I9300 using Tapatalk 2

[Balders]

got mine fixed vertically to my winglet on two straws. That way they can bend on landing without stressing the wire.

[bigMouse]

Making the dipole is rather straightforward, elements would be 173mm length for 433mHz, and 163mm for 459mHz.

I kind of discounted horizontal polarization, mainly on the grounds that a Dipole would then be required at the tx as well (methinks) Don't think a horizontal whip would be a good choice.

A trailing lower element wouldn't be ideal, maybe if it was sprung loaded at the base, or lashed to a sprung loaded, non-conductive arm.

Will be interested in any solutions...

[MrBen]

The guide I was looking at indicated a specific length for the coax leading to the element, is that set in stone? As I would like coax to run from my uhf rx to the winglet if possible.

[bigMouse]

I'd say no, nothing is actually happening within the coax, have a few different Rx's here and none have feeder length's that remotely resemble multiples(or sub-multiples) of the operating wavelength, (and some are made by Sid Huang)
Just the longer the coax, the greater the losses, but probably very little noticeable impact on the Rx side.

I'll probably end up doing what your saying, extend the feeder so the antenna can be taped to the winglet.

[jsxx]

Making the dipole is rather straightforward, elements would be 173mm length for 433mHz, and 163mm for 459mHz.<br /><br />I kind of discounted horizontal polarization, mainly on the grounds that a Dipole would then be required at the tx as well (methinks) Don't think a horizontal whip would be a good choice.<br /><br />A trailing lower element wouldn't be ideal, maybe if it was sprung loaded at the base, or lashed to a sprung loaded, non-conductive arm.<br /><br />Will be interested in any solutions...

I think it should be 164mm for 433mhz.....

.GT-I9300 FOX

[bigMouse]

wavelength = speed of light/frequency

lambda = 300000000/433000000 = 0.69284 meters so 1/4 wavelength = 0.69284/4 = 0.1732 meters or * 1000 = 173.2mm

Speed of sound used was appx. actual is 299792458 m/s which would have produced 173.09 mm

[Balders]

wavelength = speed of light/frequency

lambda = 300000000/433000000 = 0.69284 meters so 1/4 wavelength = 0.69284/4 = 0.1732 meters or * 1000 = 173.2mm

Speed of sound used was appx. actual is 299792458 m/s which would have produced 173.09 mm

I suspect given the above you know these things far better than I, but I'm sure I had read somewhere about using a 95% calculation to allow for something like atmospheric interference or something?

[bigMouse]

ah right, somewhere buried in antenna theory, the 0.95 applies to antenna's that use a decent diameter rod/tube. It's an in-depth calculation and at best open to tests afterwards. the thinner the rod/wire becomes, the more the 0.95 factor creeps nearer to 1.

Possibly a reasonable approximation for our rx wire might be 0.98~0.99 That would alter the 433 length from 173.1 to 169.6, 171.4 about 3.5 ~ 1.5mm. The amount is still approximate and in my view, small enough to ignore.

I've noticed that most articles on rc and vtx/vrx antennas, specifically CL, SP, and Helical's ignore that correction factor too with good results and low swr, so it would be a good idea to ignore it, at least as far as we are concerned...

Just for the record,  I'm only an amateur, so would bow to higher knowledge on the subject.

[jsxx]

So why on every lrs is made with 164mm dipole? Inc cl, rl, dl, tlrs?

.GT-I9300 FOX

[bigMouse]

Quite simple, they have used the 0.95 velocity factor...
But not on the Video tx/rxs to good effect(which makes a bit of a mockery of using 0.95)