On 6/15/2020 8:09 PM, Wes Attaway (N5WA) wrote:
This has been an interesting discussion.
The comparative results are very interesting in the sense that as Jim Brown
explains the nulls can be very deep but also fairly sharp. I find it
interesting to switch around between these antennas on different bands and
different times of day because the best RX results are often not what you
would expect.
Yes, I often do that, but it's easy to be fooled by signal to noise and
AGC. To reduce that possibility, it can often be necessary to turn off
AGC when making comparisons.
In addition to focusing on the directional peaks and nulls you also have to
think about the elevation angles that come into play. These angles, over
any particular path and band, can change from hour to hour and affect the
results that you get.
I often see the same things Jim does where a signal is stronger off the end
of one antenna than it is off the expected main lobe direction of another
antenna.
That's not what I meant in my last paragraph below. They pretty much
behave as expected, but I work a lot of east coast when I'm working JA
on a dipole that has the east coast sort of off the end, and a lot of JA
when I'm working the east coast on the antenna with JA sort of off the
end. So my point is that yes, the nulls are there, but so broad or deep
that the antenna doesn't work well enough in those directions to make QSOs.
73, Jim K9YC
-------------------
Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
-------------------
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of
jimlux
Sent: Monday, June 15, 2020 4:36 PM
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Inverted Vees
On 6/15/20 1:45 PM, Jim Brown wrote:
On 6/15/2020 11:18 AM, john@kk9a.com wrote:
Also an inverted V does not have the big nulls that a flat dipole has
making the inverted V's orientation is less critical.
Calling the nulls "big" is not accurate -- the nulls ARE deep, but they
are also relatively narrow in angle. i have dipoles at right angles to
each other for 80 and 40 at 120 ft. On any given signal, I rarely see
more than 10 dB difference between them, and I work a lot of east coast
stations on 80M on the antenna that's off the end to them. And I've
worked a lot of JAs on the antenna that's broadside to the east coast
and EU.
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|