You wont get 3dB at best for a 3 element yagi on 20m using a 30'
spacing is 2.5dB max. Add in an additional say 20' of cable say rg213
and you will have more loss. say another .25dB.
That assumes there is no VSWR loss.
I currently have 2 6 element tribanders at 71 and 39' stacked
I use 25' RG213 to feed both and a simple switch. I do not adjust for VSWR
you can get a stackmatch form WX0B
Yes I pick up about 2.5 dB gain but what's more important
is the take off angle and reduced fading.
Besides stacking 2 24' antenna is a lot easier than trying to keep a 60'
boom one up
and you have the ability to split the stack if designed right
David Jordan, Pr. Antenna Engineer
> Automotive Telematics and Commercial Antenna
> M/A-COM, A tyco INTERNATIONAL LTD. COMPANY
> 1011 Pawtucket Blvd. Lowell, MA 01853, MS 158
> ph: 978-442-4190 fx: 978-442-5419