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Phased Array vs Incoherent Addition

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So, I'd like to get into more serious observational radio astronomy and observe more than just the sun & moon. This kind of stuff are visible with an optical telescope (and even with the naked eyes), so not very interesting.


The largest dish I've found is an offset of 1.00x1.10m for sale for 35 EUR. There are some that are a tiny bit larger in my area, but the price increases exponentially, so it'd be worth getting many 1-meter ones and then somehow combining the signals together instead? In terms of sensitivity, what is the most ideal way to do this? Add the signals together in the superheterodyne system? Or have many separate systems and then average the data together? Many separate systems would not be the most cost effective solution (because I'd have to purchase everything n times), so I'm not really sure what to do.


Also, is there any "quality" receiver I could replace my dead HackRF with? Getting an upgrade would be a rational reason to dump the HackRF which I paid quite some money to get.. ?


- Coto

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I presume by this you want to know if interferometry will work for amateur setups... Well I suppose in theory yes.

You have best constructive interference when the peaks of two waves are offset by less than 1/10th of the wavelength. For the hydrogen line this means you have a total of 2.11cm slack in either direction. You could use a waveguide or coax cable of equal length (which join together into the receiver) and so long as both dishes are pointing at the same spot, and are positioned equally on the axis of observation (within that 2.11cm slack) you will have the power of two 1m dishes instead of 1! (in theory).


The trouble with this, besides the obvious headache with alignment and positioning, is that you *only* have twice the gathering power, but if you had one 2m dish (taking up the same space) you would have four times the gathering power. True, you get the benefit of increasing the baseline for narrower and narrower beam width, but if you don't have the sensitivity for it it will be wasted.


That's my take on it anyway, now we await someone who knows much more than I do to correct me... ?

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