Technical, Techniques, Hints, and Tips > Radio Equipment

Stubby aerials

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BobF:
Hi Roy,

I will be seeing Ted on the 20th of this month.  I will try and remember to get as much detail as I can from him, as to exact model of transmitter etc. and also the length of his receiver aerial as well. Although the pond he sails on would be just about the limit you mentioned, he goes to open days around the country, and I have never heard him complain of being low on range. He sails it at Wilton park on their open day, and that is quite a large pond/lake?

I use the 2mm gold bullet connectors for my aerials. I never worry too much about the length, as long as it is no shorter than the original. On my One Meter yachts, I just clip it to the base of the mast. So that means on a calm day with little wind and No1 sails fitted, it is the original length plus 72 vertical inches. I can sail approx 90 meeter's with the transmitter aerial down before I run out of pond !!!!!!!!!!!!!!! (only done as a range check)

Bob

Doc:
Mankster,
Helically wound antennas can be directional, but not at the commonly used R/C frequencies.  At 40 Mhz they behave as they do at HF frequencies, merely shorten the antenna, they are not directional.  Pointing the antenna at the boat does not help, as a matter of fact, it will shorten range.  There's typically a 'null' off the 'pointy' ends of antennas, less radiated signal than off the 'sides'.
If pointing the antenna at your boat does seem to help, I'd guess that your receive antenna is more horizontal than vertical (polarized).  An antenna that is helically would is only directional if the transmitted signal is a 'circular polarization'.  The dimensions of a circularly polarized antenna are based on wave length, and at 40 Mhz, would be very uncomfortable to lug around, as in very large.
Another little 'gem' is that most helically would antennas are very inefficient, lossy.
 - 'Doc

BobF:
Hi roycv,
Finally spoke to Ted regarding range problems.

He has never had a range problem with his RC equipment.
I did not get the model number, but it is from the 2000 era. The last of the batch before the company changed hands previously. Hope this is of some help.

Bob

roycv:
Hi Bobf thanks for your response, perhaps there is a fault in the aerial I have.
regards Roy

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