[TowerTalk] 15 Meter Yagi Stacking

[Stan Stockton]

>K1MK wrote:

>From New England, Europe subtends approximately 40 degrees of 
>azimuth (35 deg (TF) to 74 deg (ZB) from Boston). There may be some 
>differences in opinion over how much additional coverage is necessary 
>to not exclude adjacent areas in Central Asia, N. Africa and the 
>Middle East, but it's difficult to see too narrow of a beamwidth 
>becoming a concern, even from New England, except perhaps for >monster Yagis (that 7-el 10m M2 on the 44' boom still has an HPBW of >43 degrees).

Exactly correct!

>Of course, putting a 40 degree wide pattern onto a 40 degree wide 
>target does place a premium on accurate alignment, particularly for a 
>fixed stack... which would include finding True North ;-)

It seems a lot of guys are talking about HPBW and "coverage area" as if their signal disappears when it is down 3 dB.  Hard to imagine you could say you are not covering an area when you are 30 over nine where you are pointed and down even 6 dB at some number of degrees off where you are pointed.  

>A trade study of going from 4-el to 7-el and whether the ~2 dB of 
>additional peak gain compensates for the ~10 degree reduction in >HPBW can be evaluated using a tool like VOAAREA to generate >coverage maps.

See above regarding coverage areas.  We can forget the HPBW on the larger antenna if we are comparing the two antennas.  Sure it is less.   The question is what is the - 5 dB beamwidth of the larger one.  It is not a fair comparison tfor the larger antenna to just say the HPBW is reduced by 10 degrees when it is 2 dB stronger at its HPBW than the four element one is at its HPBW point.  

Stan, K5GO