Modify 10 element yagi

[amos1]

I have an old 88 to 108 yagi from RS I think it has 10 elements three driven. I would like to use it to receive aircraft. Can I modify this antenna so it would work on the aircraft band?? I can rotate it to vertical. Would I need to shorten the driven elements.
Thanks for your help.

 

[mancow]

It's probably close enough that it would still work.

 

[RadioDaze]

Yes, it's worth trying it as it is. Otherwise you have to shorten the reflector, driven element, and all the directors the correct amount, AND change the spaces between all of them as well. (To do it right, anyway.)

 

[amos1]

It wouldn't be hard to shorten the elements but changing the spacing would more of a problem. I think I will just put it up and see how it works as is.
Thanks

 

[prcguy]

It probably won't work very well as it is, directors have a very sharp cutoff going high in frequency compared to lower. There was a lot of design effort that went into the antenna making it cover a 20MHz span around 100MHz, its not gonna go 20-30MHz higher without another big design effort.
prcguy

 

[RadioDaze]

pcrguy, if I want a (custom) yagi that I need to be able to cover, let's say 484-507MHz, are you implying that I should shoot for the high side of that range rather than splitting it down the middle?

tnx,
Doug

 

[prcguy]

A UHF yagi will have much more bandwidth than a VHF and the range you mention is usually not a big deal at UHF. I would go for the center in that case.

The RS FM yagi has three driven elements (probably log periodic style) to cover the bandwidth and the directors are a compromise compared to a conventional yagi. The same yagi with a single driven element and optimized for say 100MHz might only have a few MHz BW but will have more gain and a better pattern.
prcguy

pcrguy, if I want a (custom) yagi that I need to be able to cover, let's say 484-507MHz, are you implying that I should shoot for the high side of that range rather than splitting it down the middle?

tnx,
Doug

 

[RadioDaze]

Thanks, prcguy!

Sorry for dyslexifying your handle on my last post.