I remember reading Cebik's design articles on Moxon antennas where he
pointed out their advantages (smaller size, wider bandwidth), but one of
the things he noted was their strong degradation due to nearby metallic
structures. The Moxon design is very dependent on tip-to-tip coupling
of the elements and it doesn't take much to throw that off.
On 3/28/2012 6:37 AM, Steve London wrote:
> Hi Yan,
> Some comments below.
> Steve, N2IC
> On 03/27/2012 09:00 PM, Yannick (XV4Y) wrote:
>> Just a follow-up about my antenna and the path to NA.
>> During last CQ WPX SSB I had only a few hours that I spend on 15m
>> exclusively. Saturday morning I had 30 minutes around 8am local time (01.00z)
>> when condx should be good to NA.
> The usual short path opening from western NA to SE Asia.
>> Condx were Ok but not great. Signals were
>> down 1-2 points on the 2elts Moxon heading 15° compared to the vertical. I
>> was unable to find a good beam turning the antenna 15 degrees more or less.
> The Moxon has some serious interaction with other antennas or metallic objects
> when pointed in that direction.
>> Sunday evening (13-17z) I spend nearly 4 hours on 15m and the band was really
>> hot. The Moxon (at 330°) was 2 S-point better on european signals compared to
>> the vertical. I had plenty of S9+10db signals all over the band but it was
>> tough to make QSOs! I think my signal (with 100w) was arriving S7-9 but the
>> band was full of QRM in Europe so many time I had to wait the frequency to be
>> clear (not hearing the other stations) and at one time had an easy QSO.
>> More surprising later in the night, signals from NA were good also, around 1S
>> even if slightly off-bearing.
> Long path to eastern USA. That is a surprisingly common opening for the east
> coast to work SE Asia while both sides are being towards Europe.
>> I have two (temporary) conclusions from this : - On the morning perhaps the
>> path is not fully SP or LP and usually NA stations are bearing to JA, not me,
>> making things harder to understand.
> From the western USA, the beam heading to JA and XV are almost the same -
> the 310 to 330 degree range.
>> - Around 1 meter under my antenna I have
>> a roof which frame is in metal. Length is around 10m... If heading 330°the
>> main dimension is parallel to the antenna. Heading 015° perhaps the frame act
>> as a parasitic element and modify the radiation pattern...
> That, or some other nearby metal, is the problem.
> Steve, N2IC
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