[TowerTalk] Inverted Vees

[Jeff Blaine]

Don't discount the participation of other wires, antennas or metals in 
the area.  Everything in the near field will participate to some extent 
which is why deep modeled nulls seen are often hard to see at anywhere 
the depth one may expect based on model observations.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 6/15/20 11:04 PM, Jim Brown wrote:
> 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 at contesting.com] On Behalf Of
>> jimlux
>> Sent: Monday, June 15, 2020 4:36 PM
>> To: towertalk at 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 at 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.
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