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Thread: Crosshair makes a great dish feed!

  1. #1
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    Talking Crosshair makes a great dish feed!

    Thanks ibcrazy!

    I have tried over a dozen different circularly polarized antennas as dish feeds and so far, the Crosshair antenna has them all beat! I first made the crosshair antenna exactly as described, with a 4" by 4" square reflector, and it worked very well as a standalone antenna, but after testing it as a center feed on a 0.34 F/D parabolic dish, I saw pretty decent results, but I knew from previous testing with other feeds, that it would work much better with a 4" diameter round reflector instead. So after the switch to a round reflector, I started seeing what this antenna can really do as a dish feed!
    For the most part, the results I was getting were the most consistent and rock solid I had ever seen, regardless of whether im using a 2Watt AWUS036NHR or a 500mw AWUS051NH.
    Good weather or bad, high humidity or very low, inside or outside, the Crosshair worked amazingly well.
    And yes I'm dead serious, I have an entire non-penetrating roof mount indoors. I live in the sticks and im getting solid "potentially" usable signals from networks over 30 miles away. I actually do pay for internet access and get great upstream and downstream speeds, so I can assure you that do nothing more than network scans.
    Raleigh Distance can kiss my $$$! Just kidding haha
    Actually I just set up a bbq grill "parabolic grid dish" one day for the heck of it and picked up over a dozen networks, on accident. Well that got my attention and ever since I've been tweaking my setup, it seems the elevation levels surrounding my area drop around 100 feet, and once you get above around 2 stories up and pointed 10 miles out, its rf madness!

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  2. #2
    Engineer for Jesus Christ IBCrazy's Avatar
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    Awesome! Where did you get the parabolic reflector from?
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  3. #3
    Nice! I was thinking of doing this with my 24dbic dish. Does this reverse the polarity of the antenna? For example if your crosshair is RHCP will the dish make it LHCP because of the reflection off the dish?

  4. #4
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    It's a 2-piece TP-Link 24" x 39" that I added on to. I did this primarily with hopes that I could get the same CP broadcasts inside as I was getting outside. I checked the RF data with a metageek wispy device. But indoors I have always had trouble seeing those same LHCP and RHCP broadcasts due to the drywall, plywood, insulation, and siding lol. Its probably hopeless to pick up any circular broadcasts indoors, but regardless, the crosshair produces the best results outdoors for all polarization types CP/vertical/horizontal

  5. #5
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    Yeah that is always the case, personally I make every feed in both RHCP and LHCP.

    IBCrazy, can the turnstile antenna be placed over a reflector and still function the same way?

  6. #6
    Engineer for Jesus Christ IBCrazy's Avatar
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    Quote Originally Posted by soulcatharsis View Post
    IBCrazy, can the turnstile antenna be placed over a reflector and still function the same way?
    Yes, we call it the Crosshair

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  7. #7
    Engineer for Jesus Christ IBCrazy's Avatar
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    Quote Originally Posted by SierraRC View Post
    Nice! I was thinking of doing this with my 24dbic dish. Does this reverse the polarity of the antenna? For example if your crosshair is RHCP will the dish make it LHCP because of the reflection off the dish?
    Yes. You'd need to flip the elements upside down. LHCP when reflected becomes RHCP. Mind you, you need to proper dish. ARRL antenna boo chapter 19 goes over how to make a dish feed work. It's actually pretty easy if you can find the focal point.

    -Alex
    If it is broken, fix it. if it isn't broken, I'll soon fix that.

    videoaerialsystems.com - Performance video piloting

  8. #8
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    a good way of finding the focal point of an unknown dish:
    1/ cover it with aluminium foil
    2/ place a wood stick (painted in black) in the center of the dish, orthogonal to it (be accurate on that part)
    3/ aim the dish it at the sun (use the stick shadow to aim... when the stick has no more shadow, you're good)
    4/ the stick will burn at the focal point...
    5/....?
    6/... profit...

  9. #9
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    thats a lot of aluminum foil!

  10. #10
    MAV designer
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    it depends on the diameter of the dish...

    aluminium foil is cheap, easy to wrap on the dish... but if you prefer mylar, use a foil blanket... alsol cheap, but harder to place on the dish surface

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