- #1
Yakult
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Hi guys,
I'm in my final year of my physics degree and for my first semester project I had to make a dipole radio antenna, and it's proven to be quite tricky (at least in the theory side of things). I would seriously appreciate some help with a few things if anyone has anything to offer :)
Firstly, I don't understand the beamwidth thing at all. How is it calculated? The best I've managed to find is images of the ideals but with no information as to how they're found, or an explanation. Here's the images I found of the patterns for the height I'm using:
Single Dipole ~7m (lambda 1/2) above ground
http://www.jupiterradio.com/antenna/single-dipole-7m.png
x ... ground plane - z ... zenit
http://www.jupiterradio.com/antenna/single-dipole-7m-top.png
top view
I used a ~25m length of coax as my feedline because I wanted to take readings for 48 hours to try and get some galactic drift readings so needed to keep the laptop and receiver indoors: will this have any major effects on my readings?
Also, would I go about calculating the gain of my antenna, and what exactly IS gain?
I set up a single half-wavelength, East-West dipole, ~7m off the ground and ~7m in total length (two ~3.5m monopoles, centre fed) to receive waves of ~22MHz. This was attached directly to the receiver, which was in turn connected to the laptop. Is that the right way of doing it?
Sorry if these are newbie questions, I'm just really struggling to get to grips with it all!
Thank-you so much in advance!
PS If anyone's wondering, I modeled it closely on http://radiojove.gsfc.nasa.gov/" . I would have taken readings of Jupiter but unfortunately after 9 weeks they still hadn't sent the receiver so I had to make do with a ham radio receiver and only had time to set up the single dipole :(
I'm in my final year of my physics degree and for my first semester project I had to make a dipole radio antenna, and it's proven to be quite tricky (at least in the theory side of things). I would seriously appreciate some help with a few things if anyone has anything to offer :)
Firstly, I don't understand the beamwidth thing at all. How is it calculated? The best I've managed to find is images of the ideals but with no information as to how they're found, or an explanation. Here's the images I found of the patterns for the height I'm using:
Single Dipole ~7m (lambda 1/2) above ground
http://www.jupiterradio.com/antenna/single-dipole-7m.png
x ... ground plane - z ... zenit
http://www.jupiterradio.com/antenna/single-dipole-7m-top.png
top view
I used a ~25m length of coax as my feedline because I wanted to take readings for 48 hours to try and get some galactic drift readings so needed to keep the laptop and receiver indoors: will this have any major effects on my readings?
Also, would I go about calculating the gain of my antenna, and what exactly IS gain?
I set up a single half-wavelength, East-West dipole, ~7m off the ground and ~7m in total length (two ~3.5m monopoles, centre fed) to receive waves of ~22MHz. This was attached directly to the receiver, which was in turn connected to the laptop. Is that the right way of doing it?
Sorry if these are newbie questions, I'm just really struggling to get to grips with it all!
Thank-you so much in advance!
PS If anyone's wondering, I modeled it closely on http://radiojove.gsfc.nasa.gov/" . I would have taken readings of Jupiter but unfortunately after 9 weeks they still hadn't sent the receiver so I had to make do with a ham radio receiver and only had time to set up the single dipole :(
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