OK, so I have one of these to repair, which is missing the "tail" antenna on the transmitter.
Now I know very little about RF, antennae etc. I can't get a replacement antenna for this, so how feasible would it be to make one?
I assume this will be a fine coil of wire covered in rubber, e.g. a tiny rubber ducky?
Or could you just attach a long wire and roll/pack it up and attach the blob to the guitar/guitarist?
Cheers,
Gareth.
Rather than the "fine coil of wire" you mentioned, it is likely just a piece of wire. The length should be the about the same as the original. The length would be similar to the length of the antennas on the base unit.
It would help to know the frequency range this operates on. Looks to be about 6 inches of wire. If it is operating close to 450 MHz, then about
6 inches of wire is all that is needed. Measure the antenna on the receiver and use a piece of wire that long.
It would help to know the frequency range this operates on. Looks to be about 6 inches of wire. If it is operating close to 450 MHz, then about
6 inches of wire is all that is needed. Measure the antenna on the receiver and use a piece of wire that long. *************************************From the manual:
It operates in the uncrowded 801 ? 805, 863 ? 865 MHz UHF frequency range
Gareth.
In that case the antenna should be about 3 1/4 to 3 1/2 inches long. If you are using wire that is insulated, just make it 3 1/4 inches.
That is probably close to the origional length.
That makes it a 1/4 of an electrical wavelength long.
For a low power short range piece of equipment, I doubt it makes much difference on how long it is, from 3 inchs to a foot long.
In that case the antenna should be about 3 1/4 to 3 1/2 inches long. If you are using wire that is insulated, just make it 3 1/4 inches.
That is probably close to the origional length.
That makes it a 1/4 of an electrical wavelength long.
For a low power short range piece of equipment, I doubt it makes much difference on how long it is, from 3 inchs to a foot long.
******************************************OK, so the "antenna" is just a piece of wire then.
Blimey.
Gareth.
In that case the antenna should be about 3 1/4 to 3 1/2 inches long. If you are using wire that is insulated, just make it 3 1/4 inches.
That is probably close to the origional length.
That makes it a 1/4 of an electrical wavelength long.
For a low power short range piece of equipment, I doubt it makes much difference on how long it is, from 3 inchs to a foot long.
**********************************Thanks, Ralph, you have made my day.
I thought it was much more complicated than a piece of wire.
Gareth.
It can be, this is a topic that of late is near and dear to my career.
Antennas are a science to themselves. Any piece of wire can be an antenna, but if you want efficiency and range, things get a *lot* more complicated quickly.
It's far too broad a topic to cover here, and there is plenty written about it on the web (not all of which is correct). It's safe to say that for your application, a hunk of wire is sufficient.
Terry
But a yagi would be fun.
Good exercise, you could say...
Mike.
Simple antennas are not that complicated. Juat a piece of wire 1/4 of a wavelength long should work fine for that application.
When you get much below 450 MHz and want an antenna shorter than around
6 inches is when it will get somewhat complicated . Then they look like a spring under the insulation.There is a number around 234 that if you devide it by the frequency in MHz you will get the length of a simple 1/4 wave antenna.
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** While possible, it is just as likely to be a simple 1/4 wave whip.** Err- no.
.... Phil
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frequency range
** Normally a straight, 1/4 wave length whip antenna does the job well. Hel ically wound antennas (rubber duckies) are not better, only shorter and les s efficient. I note the owners manual says the antennas are 1/4 wave.RF travels at 300,000 km/S so 830 MHz has a wavelength of 360mm, 25% of whi ch gives you 90mm from the attachment point inside the Tx. A 5% "end correc tion" can be applied so make it 85mm.
Use wire that has a stiff cover like Teflon, to hold it out straight.
... Phil
It could be a coaxial type full wave.
Greg
OK, so I have one of these to repair, which is missing the "tail" antenna on the transmitter.
Now I know very little about RF, antennae etc. I can't get a replacement antenna for this, so how feasible would it be to make one?
I assume this will be a fine coil of wire covered in rubber, e.g. a tiny rubber ducky?
Or could you just attach a long wire and roll/pack it up and attach the blob to the guitar/guitarist?
Cheers,
Gareth.
****************************************Well a piece of wire worked a treat.
With a bit of heatshrink for strain relief at the transmitter end and another on the end of the tail, it even looks like a proper one.
Thanks to all for the calculations and info.
Cheers,
Gareth.
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** So now you know how to make a "rat tail" antenna.** 300 / MHz = wavelength in metres, is worth remembering.
FYI:
That AG-1 unit is about as basic as UHF FM links get, so has limited useful range and is prone to signal drops out due to multipath interference. The Tx signal can almost cancel itself after reflecting off objects and surfaces and then arriving at the Rx.
Better models have twin channel receivers, with two separated antennas, operating as a diversity pair that helps greatly to eliminate such drop outs.
.... Phil
Meant 1/2 wave.
Greg
-----------------------
** So now you know how to make a "rat tail" antenna.** 300 / MHz = wavelength in metres, is worth remembering.
FYI:
That AG-1 unit is about as basic as UHF FM links get, so has limited useful range and is prone to signal drops out due to multipath interference. The Tx signal can almost cancel itself after reflecting off objects and surfaces and then arriving at the Rx.
Better models have twin channel receivers, with two separated antennas, operating as a diversity pair that helps greatly to eliminate such drop outs.
.... Phil
******************************************Presumably the transmitter antenna should be straight for best efficiency.
If it is (worst case scenario) a semicircle, what changes?
Gareth.
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** Every effort should be made to straighten it !It's an FM signal, so the recovered audio is not affected until the RF level becomes very weak. Meaning there is usually plenty in reserve to allow for circumstances that reduce the RF level compared to free field.
Players buy units like this not to get long range, but merely to be free of that damn instrument cable.
.... Phil
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