Topband: 160 meter 1/8 wave

[Richard (Rick) Karlquist]

On 4/1/2021 1:48 PM, Dave Cuthbert wrote:
> Hi Doug, for now I will assume you mean an inverted-L with apex at 1/8
> wavelength. Let's see what EZNEC shows for a top hat vertical at the
> extreme against the inverted-vee. We can refine the model with more input
> from you such as take-off-angle, top hat design and ground parameters. From
> that a practical loading coil is added either at the bottom or at the top.
> 
> 1.8MHz
> *65' vertical* with top hat sized for a nearly square current distribution
> 6 x 20' top hat
> Loading coil not required, antenna is resonant at 1.8MHz
> 32 x 130' radials plus 5 ohm GND loss added to try to account for NEC-2
> 0.005S/13 GND, "average"
> Gain at a 10 deg take-off angle =* -2.5 dBi*
> 
> 1.8MHz
> Inverted-V apex at 65' with ends 10' above GND
> 0.005s/13 GND, "average"
> Broadside gain at a 10 deg take-off angle = *-10.5 dBi*
> 
>       dave KH6AQ
> 

The original poster asked about an inverted-L and you simulated
an inverted-V.

When doing these simulations, it is extremely important to use
the "Desc Options" menu in EZNEC and select "Vert Horiz" as
opposed to the default which is "total".  Vertical is the "money"
polarization on 160, in most cases.

FWIW, I had to operate in a 160 meter contest once with a 60
foot top loaded vertical.  It had two very long top loading wires
that sloped down to the ground and I pruned them for resonance at
1830.  The bandwidth was much narrower than my usual 90 foot
vertical, which was already fairly narrow (this is actually GOOD). 
Anyway, it worked great in the contest (subjective opinion) although
I couldn't A/B it with the 90 foot vertical.

My feeling was that the 60 ft vertical probably got out nearly
as well as the 90 ft vertical, but the very narrow bandwidth would
have required a suitable antenna tuner for effective on the air
use.  Any 60 ft vertical that does NOT have very narrow BW is probably 
not very efficient at least when it comes to vertical polarization.

73
Rick N6RK