Topband: Palmyra cursed paradise (K5P)

[Grant Saviers]

I did some modeling of radials with elevated radials after 3 "on the 
beach" DXpeditions.  QST said they will publish it this year, sometime.  
Rudy N6LF has done a lot of modeling of elevated radials see 
antennasbyn6lf.com and his QEX articles.

 From my modeling: There is quite a bit of improvement in low angle gain 
(<15 d) for verticals with elevated radials within 1/4 wavelength of the 
tide line.  As far back as one wavelength there is some good low angle 
(<7 d) gain improvement.  Two elevated radials parallel to the tide line 
work well.  Further back than 1 wl, the pattern reverts to a normal 
vertical so lots of ground radials or 8+ elevated radials yield normal 
vertical patterns. Neither has the gain of a near salt water vertical 
below 10 d.

The ground conductivity of an atoll is an interesting question, at what 
depth is there salt water?  For wet sand the conductivity is probably 
about 1/4 that of the sea, still great at 1 S/m vs soil. So over wet 
sand elevated radials are FB, but over several feet of coral to salt 
water ??  I think subsurface fresh water on a true atoll is pretty rare 
and full salt water incursion is the norm.

It is surprising to me that K5P isn't stronger here near Seattle, that 
has me wondering where they were required to put their antennas.  The 
tide line separation may explain why they are reported stronger on 160 
than 80.   Web photos of Palmyra show what appear to be a big tidal 
range and an atoll becoming an island. Tide cycles might be involved in 
how well they get out.

Grant KZ1W

On 1/16/2016 15:54 PM, Mike Waters wrote:
> Hi Art,
>
> Whether or not elevated radials would help K5P, what you stated is NOT pure
> speculation! :-)
> Generally speaking, it is well-established that we can use far fewer
> elevated radials under a vertical than ground mounted radials, for the same
> efficiency.
>
> 73, Mike
> www.w0btu.com
>
> On Sat, Jan 16, 2016 at 5:22 PM, Art Snapper <art at nk8x.net> wrote:
>
>> I wonder how good the ground conductivity is on an atoll? Perhaps
>> elevating the radials would help.
>>
>> My $0.02 of pure speculation.
>>
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