Topband: Seeking advice for TO5M

[Grant Saviers]

You don't mention how high you will be above sea level.  Too high and 
the "L" gain & angle won't improve as much as within 1/2 WL and a few 
meters above sea level.  So the 160L is ok at 80m from the tide line but 
the 80m ought to be closer if you can manage that.  More than a 
wavelength from salt water and a vertical is pretty much a normal over 
dirt vertical.

I'm a believer in elevated radials for expeditions.  Two resonant ones 
work within a fraction of a db of 4 or more elevated.  Only one and its 
less than 1.5db such as the steppIR crankIR. It still takes a lot of "on 
the ground" radials to minimize the ground losses, even close to salt 
water (perhaps unless there is salt water intrusion just below ground 
level).

Rudy Severns has done a lot of research and modeling. 
antennasbyn6lf.com. Relative to more compact elevated radials, check his 
article "Short Radials for Ground-Plane Antennas" in the ARRL antenna 
Compendium vol 6.  A single inductor and two elevated radials as short 
as 1/8 wl are within a fraction of a db from 1/4 wl.  My plan for my 
next DXpedition.

I've used DHDL's which have RDF much better than BOG's, which really 
don't work over salt water infused soil/sand/coral.  It's easy to make 
DHDL's switchable 180 deg, which might be useful EU vs US. If you are on 
granite then the usual 200' BOG length advice seems ok, but I've not 
tried them.  But most any Rx only antenna will help, especially if you 
have diversity synchronous radios (e.g. K3 with 2 receivers for CW or 
SSB integration in your head).  Sometimes the noise rejection worked on 
bands not expected (eg 15m Rx on an 80m DHDL).  Experienced but not modeled.

No experience with VP2E's.

Good luck, have fun and I hope to work you!

Grant KZ1W

On 6/29/2019 4:21 PM, Martin wrote:
> Topbanders,
> Operators from VO and DL teamed up to go to Ile aux Marins, a small 
> abandoned island just a few 100 meters from St.Pierre , FP . We are 
> right now planning our antennas.
> 
> There is daily tourism on the island , so the antenna farm can not be 
> big. The location is about 80m from the sea, so we hope for good take 
> off angles.
> 
> For RX, we plan to use BOGs. How long should we make them?  Do you think 
> this may work?
> 
> For TX on 160m and 80m we plan to install inV L's with radials on the 
> ground. What number do you suggest minimum near salt water?
> 
> 40m vertical , 30m vertical: Will we be better off with VP2E's or with 
> verticals and radial field? What do you think? Any hint welcome.
> 
> Other bands: Hexbeam.
> 
> Please visit www.fp2019.net
>