Spacing Calc Help
Spacing Calc Help
Trying to figure out how to do the calculation's properly.
my target frequency 144.510
I need to understand what distance apart the antennas should be .
I am not following the calculations properly, but if someone could walk through them using my desired frequency it might help. Once i see it once with real #'s, it will make sense for me....
Thanks
Mike
my target frequency 144.510
I need to understand what distance apart the antennas should be .
I am not following the calculations properly, but if someone could walk through them using my desired frequency it might help. Once i see it once with real #'s, it will make sense for me....
Thanks
Mike
Re: Spacing Calc Help
Ideally you want about 1/3 the wavelength.
Wavelength = 300/MHz
In your case 300/144.51 MHz = 2.08m
Then just do wavelength/3
So 2.08/3 = 0.693m
You then make a square where each side is 0.7m.
The current Quickstart guide is a little outdated with having to do more calculations manually. The latest KSDR software allows you to enter your element spacing in meters and the rest happens in the background.
The antenna array will be able to handle a pretty wide range of frequencies at a fixed spacing as long as the spacing between the elements doesn't exceed 1/2 wavelength or fall below 1/10 wavelength. You could build an array for VHF and an array for UHF.
Wavelength = 300/MHz
In your case 300/144.51 MHz = 2.08m
Then just do wavelength/3
So 2.08/3 = 0.693m
You then make a square where each side is 0.7m.
The current Quickstart guide is a little outdated with having to do more calculations manually. The latest KSDR software allows you to enter your element spacing in meters and the rest happens in the background.
The antenna array will be able to handle a pretty wide range of frequencies at a fixed spacing as long as the spacing between the elements doesn't exceed 1/2 wavelength or fall below 1/10 wavelength. You could build an array for VHF and an array for UHF.
Re: Spacing Calc Help
Ok, I think I was on the right track.
But, what is the number I put into the Android software then? is that also my .7? or would that be .33?
Also, I am not sure I spaced my antennas correct. Good news, I have adjustments (hard to see in the pic, but I can move the antennas in and out in 1" increments)
I have them spaced based on the red line, but I am assuming now, I need to set them to the yellow line? If that is the case, i am not sure I made my mounting set up big enough.
BUT. I suspect I can put them at the furthest point, and back my calculation back the other way to get the spacing factor I used?
But, what is the number I put into the Android software then? is that also my .7? or would that be .33?
Also, I am not sure I spaced my antennas correct. Good news, I have adjustments (hard to see in the pic, but I can move the antennas in and out in 1" increments)
I have them spaced based on the red line, but I am assuming now, I need to set them to the yellow line? If that is the case, i am not sure I made my mounting set up big enough.
BUT. I suspect I can put them at the furthest point, and back my calculation back the other way to get the spacing factor I used?
Re: Spacing Calc Help
Space it based on the yellow line and just put that measurement into the software. If it's more than 0.2m, you'll get good readings, assuming your cable lengths all match perfectly.
Re: Spacing Calc Help
Ok. so measure the yellow line, and that goes in the software (obviously in meters)
Cable lengths are all within 1-2" of each other. they were all brand new mounts with cables on them. I am just not sure how accurate my friend was when he stripped the end and put the PL259's on for me last night (his job is in the radio world, so if he is available I make him put the ends on - much quicker LOL)
Cable lengths are all within 1-2" of each other. they were all brand new mounts with cables on them. I am just not sure how accurate my friend was when he stripped the end and put the PL259's on for me last night (his job is in the radio world, so if he is available I make him put the ends on - much quicker LOL)
Re: Spacing Calc Help
After watching a couple of the videos, i need to clarify.
My yellow line - that measurement is what I put in for the spacing factor???
I got the impression it would be the .33?
I worry I have the wrong # entered, and that is part of my issue getting an accurate track.
My yellow line - that measurement is what I put in for the spacing factor???
I got the impression it would be the .33?
I worry I have the wrong # entered, and that is part of my issue getting an accurate track.
Re: Spacing Calc Help
Oh - i see the note in the startup guide saying it was changed in the latest version.... Oops.
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Re: Spacing Calc Help
k2gc wrote: ↑Mon Jan 20, 2020 5:26 pmOk, I think I was on the right track.
But, what is the number I put into the Android software then? is that also my .7? or would that be .33?
Also, I am not sure I spaced my antennas correct. Good news, I have adjustments (hard to see in the pic, but I can move the antennas in and out in 1" increments)
I have them spaced based on the red line, but I am assuming now, I need to set them to the yellow line? If that is the case, i am not sure I made my mounting set up big enough.
BUT. I suspect I can put them at the furthest point, and back my calculation back the other way to get the spacing factor I used?
antenna array.jpg
Nice setup


and

Re: Spacing Calc Help
Please clarify the "If it's more than 0.2m, you'll get good readings" part of the post. I haven't seen that measurement limitation in any of the notes.
Re: Spacing Calc Help
They're interested in DFing a frequency with a wavelength of about 2m. The circular array will work with 1/10 to 1/2 wavelength element spacing.