Thankyou verymuch to Grant KZ1W, Greg ZL3IX, Mike W0BTU, Garry NI6T and Jim
K9YC for all the suggestion.
As suggest by Grant KZ1W and Jim K9YC, I will install a half-lambda dipole
on 160M with both ends were 90 degrees bent due to the size of the building
,and find out what will be the Tx / Rx performance...
To Mike W0BTU, it is slightly difficult to install the radial for the
vertical antenna or inverted L as
the roof top is not empty flat, hi hi
Regards,
Nuradi, YB0UNC / KU2B
-----Original Message-----
From: Topband [mailto:topband-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Saturday, August 08, 2015 11:23 AM
To: topband@contesting.com
Subject: Re: Topband: [Bulk] Best wire antenna for roof top location
And remember -- the roof of this building is 110m, so a horizontal
antenna is high enough to have pretty good low angle radiation! See
http://k9yc.com/VertOrHorizontal-Slides.pdf and double the heights for
the graphs of 80M performance. When you're thinking height, consider
the building a tower -- it's mostly the far field reflection that
determines the vertical pattern.
As to "ground" for a vertical antenna -- let's not confuse the word
"ground" with counterpoise or "radial system." An end-fed current-fed
vertical needs a counterpoise or radials, NOT a connection to earth.
I strongly concur with the advice to spend some serious time LISTENING
on that roof before doing anything else. It's pretty common for the
stuff described on that roof to be MONDO NOISY, and it's unlikely that
you can do much about most of it unless the guys who maintain it are HF
hams.
73, Jim K9YC
On Fri,8/7/2015 8:02 PM, Garry Shapiro wrote:
> And Bob Brown used a monograph by J.A. Ratcliffe--"The Magneto-Ionic
> Theory and its Application to the Ionosphere" which says the same
> thing. It has to do with the angle between the E vector and the
> Earth's Geomagnetic Field, which is horizontal at the geomagnetic
> equator. Bob borrowed my copy of the book when he was writing the Big
> Gun's Guide.
>
> Garry, NI6T
>
> On 8/7/2015 6:24 PM, Greg - ZL3IX wrote:
>> Careful Mike! Jakarta is close to the equator, and power coupling is
>> likely to be better from a horizontally polarised antenna, especially
>> in an E-W direction. Ref The Big Gun's Guide to Low-Band Propagation
>> by Bob Brown, NM7M (SK)
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