[NLRS] 6m rover antennas

[John P. Toscano]

Jon Platt wrote:

> Dipole at 10' above ground :
>   Max Gain = 7.30 dBi @ 28 degrees take off.
>   Gain @ 3 degree take off angle = -7.20 dBi
> 
> Dipole at 20' above ground :
>   Max Gain = 7.68 dBi @ 14 degees take off
>   Gain @ 3 degrees take off = -1.5 dBi
> 
> 6m Quad with boom at 10' above ground :
>   Boom length = 4.2'
>   Max Gain = 11.55 dBi at 24 degrees take off
>   Gain @ 3 degree takeoff angle  = -1.95 dBi
> 
> 6m 3-ele NBS yagi with boom at 10' above ground :
>   Boom length = 7.8'
>   Max Gain = 13.25 dBi at 23 degrees take off
>   Gain @ 3 degree takeoff angle = 0.09 dBi.

Ouch!  Thanks for taking the time to run the simulations, it is
very informative.

Ok, thinking through the possibilities some more, maybe my best bet
for a "stop and shoot" type of operation would be a very lightweight
yagi that easily breaks down into a couple of pieces that are no
longer than the 12' length or 6' width of my truck's dimensions and
could be strapped to it for travel, and then mounted to a lightweight
fiberglass mast that would slip into the top section of my existing
aluminum mast when arriving at the working location.  For me, unless
I find a partner to go with me, light weight is a key feature, because
I would have to erect it and tear it down by myself, including in
total darkness in the middle of the night, and I can guarantee that
I could never swing up an 8' pole with a 6M5X on the end of it and
drop it into place!  In fact, I am amazed that I actually managed to
install it in the last rover configuration by myself in my driveway.
But maybe a yagi made with a light fiberglass tube for a boom and
stiff wire elements is something I could erect while standing on the
roof of my truck out in the middle of nowhere.  (Naturally, I WOULD
try this at home first!)

Maybe a 4-element yagi for a little more gain than the 3-element NBS
yagi that Jon modelled, which should still fit reasonably on a 12-foot
boom (same length as the other antennas), considering the 6M5X is 18
feet long with 5 elements.  This could be separated into two pieces,
6' long by 10' wide, which would fit sideways on the roof while
driving and require minimal assembly at the working site.  With an 8'
fiberglass mast dropped a foot down the existing aluminum mast, the
antenna would be at about 19' above ground level.  That should be a
whole lot better than the current setup, and street legal to boot!

So, does anyone have plans for a 4 or 5-element 6M antenna on a 12'
non-conductive boom?  (I guess, in a pinch, I could make a 3-piece
18 footer to match the dimensions of the 6M5X, and then adjust the
element lengths for the non-conductive boom, but if I used wire
elements, I'm not sure how to re-adjust the lengths further.)  I
took a look at the WA5JVB article but the "cheap yagi" designs he
presents are for 144 through 1296 MHz.  I also see a 5-element
design in the ARRL Antenna Handbook on a 12' conductive boom, with
5/8" OD aluminum tubing for elements.  On the other hand, it may
not be practical to use wire elements at frequencies this low.

More dialogue would be welcomed.  And again, I appreciate the prior
discussion greatly.

John, W0JT