[evlatests] P-band Dipole Orientations {External}

[George Moellenbrock]

Hi Rick, Rob-


Climbed ea11 today with some visitors, and mused about the P-band dipole 
orientation. FWIW...


Get out your protractors:



Notwithstanding Rob's assertion below (about ea11), the above looks a 
tad off-set clockwise-ward (looking up at it), relative to the quad 
legs.  Of course, I'm not looking straight up from the center of the 
dish, and it was best-efforts aligning myself with the quad legs (and 
the sun was bright!).    I'm not sure this looks like as much as 10 deg 
(as Rick reports), but it is easily 5 deg, I think, and Rick's 
measurement would be consistent with ea01 being at -5 deg (and Rob's 
assertion that ea01 is a bad reference), and most of the others in his 
table would be closer to zero.   Of course, there are 20+ other antennas 
that are well-aligned with ea01...


Cheers,

George





On 9/18/24 11:43, Rob Long via evlatests wrote:
>
> Hi Rick,
>
>
> It looks like our main dipole culprit is ea01. The dipole itself is 
> not orthogonal (elements twisted) and we are going to have to get with 
> the mechanics to get it removed so we can align it or install the spare.
>
>
> ea11 (on the other hand) looks to be aligned well (if you wanted to 
> use it as a reference).
>
>
> Rob
>
>
>
> On 9/10/2024 3:43 PM, Rick Perley via evlatests wrote:
>> Ther results of a polarization calibration of a recent P-band dataset 
>> (obtained via VLITE) indicate a significant number of antennas with 
>> apparently misaligned feeds.
>>
>> As this was a VLITE database, there were only 18 antennas included, 
>> one of which was out of service.  For the seventeen others, the 
>> calibration shows seven antennas misaligned by more than 5 degrees 
>> w.r.t. the reference dipole (ea01).  They are:
>>
>> ea17  5.7 degrees
>> ea07  8.6
>> ea11  10.3
>> ea20  5.7
>> ea23  5.2
>> ea27  8.0
>> ea21  8.6
>>
>> It is my impression (but I do not have the data in hand to prove it) 
>> that this is worse than what was seen a few years ago.
>>
>> These misorientations should be easily visible from the antenna 
>> surface.  It would be good to know if visual inspection agrees with 
>> the observations.
>>
>> Rick
>>
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>
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