Foldable SatCom 3D printed antenna

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Part I. :
Part II. :

STL files to be sliced:
I used 0,2mm Quality and 50% infill. Gembird filament. Support only for dipole parts.

Anybody over here with experiences to assy this SatCom foldable antenna please?
 
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HI all,

all 3D parts are printed now.
I will have to find 20mm square Al boom and some coaxial cables to make phasing lines.
Is there somebody who made it also using 3D printing?
 
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I found the source of the Al square 20mm boom and coaxial cables pieces so tomorrow I will try to pickup them.
(it is not easy during current lock down period...)

I am curious how it will work compare to my original military Trivec Avant...
 

prcguy

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It should work very similar to a Trivec with the same number of elements. The Trivec will have an advantage where its driven elements are very wide giving you more band width. I would test each dipole with an antenna analyzer to see if it resonates around 260MHz using a short 50 ohm coax before connecting the phasing lines.

You can test the phasing lines by receiving a signal with the completed antenna, measure the receive level, then swap the coax connections on the dipole to make it left hand polarity. You should see a large drop in signal, hopefully 20dB or at least the signal should disappear into the noise. That will tell you the phasing lines are a good length and are making good circular pol.
 
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Many thanks for these guide lines. It is very helpful mainly regarding the phasing line...
Just single question regarding the resonate frequency... Is the 260MHz the correct one?
If I remember well the TacSat transponders uplink are in between 290-320MHz where the TX should operate.
So I am curious if it would not be centered higher in this range please? ...or it is linked to phasing line?
Thanks for great help.
 

prcguy

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The downlink range is roughly 245 to 270MHz so I would try and tune the dipoles at the center of that. If you want to transmit this antenna will not have enough band width to do that unless you make the elements at least 2 inches wide and you use a wide band phasing solution like a 225-400Mhz 90 deg 3dB hybrid with equal length cables to each dipole. The original dipoles in this design will be narrow band, maybe 10MHz with a good match and the phasing lines will also be narrow band.

Look at post #25 in this thread for what a wide band 90 deg 3dB hybrid looks like. REALLY new to SATCOM. Looking for the most active frequencies for casual listening.

Many thanks for these guide lines. It is very helpful mainly regarding the phasing line...
Just single question regarding the resonate frequency... Is the 260MHz the correct one?
If I remember well the TacSat transponders uplink are in between 290-320MHz where the TX should operate.
So I am curious if it would not be centered higher in this range please? ...or it is linked to phasing line?
Thanks for great help.
 
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Apr 12, 2020
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Many thanks.
My elements will be 16mm wide.
Trying to copy this project:

...what do you think about it please?
Thanks a lot.
 
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Many thanks.
My elements will be 16mm wide.
Trying to copy this project:

...what do you think about it please?
Thanks a lot.
...do you thing that 16mm wide elements is ok?
 

prcguy

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I have never measured the band width of a UHF satcom dipole using 16mm wide elements so I don't know. One antenna I designed used 50mm wide elements to keep a good match over 245 to 270MHz. If you take an existing design and make the elements fatter you will have to measure the VSWR and tune the elements.

...do you thing that 16mm wide elements is ok?
 
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Many thanks. I will do that during the assembly and tuning.
I am still a bit confused if all elements of cross on director and reflector should be soldered together or not... it is not clear from guide.
Thanks!
 

prcguy

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It depends on how the antenna lengths were calculated. All grounded would be a slightly different length than floating. I would normally ground the directors and reflector to the boom for an antenna like this but it looks like they sit in plastic insulators. I would at least ground the two elements in the director to each other and do the same for the reflector.

Many thanks. I will do that during the assembly and tuning.
I am still a bit confused if all elements of cross on director and reflector should be soldered together or not... it is not clear from guide.
Thanks!
 
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Hi all,
my lock down stopped and I was called for gov. logistic and comm. mission.
So finally I had chance to bring Al square boom and flat elements material.
So I will try to assembly prototype this weekend I hope.
 
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