[Elecraft] [Sorta OT]: Does terrain affect HF radiation patterns?

[Fred Jensen]

Try HFTA, by Dean N6BV, who edited the ARRL Antenna Book for many years. 
  It's on the CD that comes with the current edition.  It will surprise you.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org

On 9/15/2014 6:54 PM, Al Gulseth wrote:
> Greetings all,
>
> I've been following some of the antenna-related discussions here recently, and
> I've decided to see what the "gurus" here have to say about a question I have
> related to my QTH. As my post title indicates, what (if any) effect does
> nearby terrain have on HF radiation patterns? Is it along the lines of VHF?
>
> Without going into too much detail, my QTH is partway up what amounts to a
> long broad slope to the north. "Just for grins" I plugged my QTH coordinates
> and an arbitrary antenna at 50 feet AGL into the FCC's Height Above Average
> Terrain calculator. Here are the results, in meters of course, which shows
> what the surrounding terrain is like; the results seem realistic from what I
> know of the local area. I would also note that the area less than two miles
> away, which is not used in these calculations, would nevertheless correspond
> fairly closely slope-wise in my estimation. I'm aware that this calculation
> is intended for FM/TV broadcast: my question is whether it could be of use
> for hams on HF:
>
> Antenna Radiation Center Heights Above Individual Radials:
>
> 0.0°    	    -107.3 meters
> 45.0°    	    -37.4 meters
> 90.0°    	    39.6 meters
> 135.0°    	    100.3 meters
> 180.0°    	    92.9 meters
> 225.0°    	    86.6 meters
> 270.0°    	    -1.6 meters
> 315.0°    	    -40.0 meters
>
> Now, my observations: I've been using an inexpensive SW portable with its
>
> built-in whip to monitor some of the International Beacon Project and 10M
>
> beacon frequencies while I'm around the house. By using the portable, in my
> estimation I achieve two things: 1) it should "hear" a mostly omnidirectional
> pattern and 2) beacons heard under this circumstance should indicate the band
> would be usable to the area in the beacon's vicinity.
>
> That being said, I have found that other than 4U4UN, I'm most consistently
> hearing South American beacons, and at least some of them can usually be
> heard if I'm hearing anything at all. So, is the terrain around me affecting
> this, or if not, what might be happening?
>
> TNX/73, Al
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