[TowerTalk] 160m antenna ideas / suggestions

[David Gilbert]

Several years ago I worked 3B9R on 160m from my QTH here in southern 
Arizona (2 miles from the Mexican border).  I live on a hillside at the 
mouth of a large canyon, so I stretched a couple of wires across it to 
make a 2 element wire yagi for 160m about 200 feet in the air pointed in 
their direction.  I had to set up portable from my vehicle and I used a 
400 watt amplifier, but even so I needed to use so much RG-8X coax (for 
light weight) to reach the antenna that I calculated I was only getting 
about 100 watts to the antenna. Still, I worked 3B9R with ease and was 
the furthest station from them to do so.  While other hams west of the 
Mississippi River were lucky to get five minutes of gray line openings I 
was hearing them S7 to S9+ for almost an hour at dusk some days.

Being rather proud of myself, I posted my results to the Topband 
Reflector and got a reply from none other than Bob Brown, NM7M, one of 
the more esteemed propagation experts on 160m propagation.  He pointed 
out that because of the electron gyrofrequency effect, he calculated 
that for the path from my QTH to 3B9 I was suffering about 11 db 
disadvantage by using horizontal polarization instead of vertical 
polarization.  Personally, I think my wire yagi still had the advantage 
over a vertical at my QTH if for no other reason than the fact that the 
ground slopes downward between 16% and 5% for about 7 miles in that 
direction thus giving me an extremely low takeoff angle for a horizontal 
antenna, but he really opened my eyes to the effect polarization has on 
80m and 160m. Over flat land and because of the electron gyrofrequency 
effect, I can understand why many hams find a vertical antenna to be 
optimum on 160m for many paths.

NM7M wrote what is still a pretty good treatise on HF propagation in 
general.  It's called Propagation 101 and can be found here:

http://www.astrosurf.com/luxorion/Radio/nm7m-hf-propagation-tutorial.pdf

Here is another of his works:

http://k9la.us/NM7M_The_Big_Gun_s_Guide_to_Low-Band_Propagation.pdf

73,
Dave   AB7E



On 1/25/2018 5:37 AM, Wes Stewart wrote:
> Of course, I know all of that stuff. And I don't contend that 
> anecdotal evidence replaces careful measurements and/or calculations.  
> What I have a problem with is your "expertise", which is simply more 
> anecdotal storytelling:
>
> "In general, verticals RULE on 160M, because ANY horizontal antenna is 
> a LOW antenna on 160M. And it will NOT be good for NVIS either, 
> contrary to urban myth. It will just be lousy for both short haul and 
> DX. "
>
> I want to see folks with an "easy" 100, 150, 200 countries on 160 move 
> their stuff down here to my patch of desert 
> (https://www.qrz.com/db/N7WS) and then tell me how "easy" it is.
>
> Wes  N7WS
>
> On 1/24/2018 10:12 PM, Jim Brown wrote:
>> On 1/24/2018 8:35 PM, Wes Stewart wrote:
>>> I have only 86 entities worked. Apparently, I failed to get the 
>>> message since sixty-seven of them were worked with an inverted-vee 
>>> dipole with apex at 45' and the ends barely above head high.
>>
>> You do know about "good, better, best," don't you? You do know about 
>> efficency, and horizontal and vertical directivity, don't you? The 
>> difference between your antenna and a much better one can easily be 
>> >10 dB. Half that csan be the difference between being heard or not 
>> on the other end, and that becomes increasingly true as local noise 
>> levels increase. N6BT has famously said "everything 'works'" while 
>> describing working all continents using a light bulb (carefully 
>> decoupled from the feedline) as his antenna.
>>
>> The first hundred countries are the easiest (the first 150 if you're 
>> around the Atlantic basin).
>>
>> 73, Jim K9YC
>