Radio astronomy - receiving the hydrogen line

[Analoguesat]

The rtl=sdr site has had a couple of interesting radio astronomy projects featured in the last few days - both looking to detect the galactic hydrogen line

Cheap and Easy Hydrogen Line Radio Astronomy with an RTL-SDR, WiFi Parabolic Grid Dish, LNA and SDRSharp

We've recently been testing methods to help budding amateur radio astronomers get into the hobby cheaply and easily. We have found that a low cost 2.4 GHz 100 cm x 60 cm parabolic WiFi grid antenna, combined with an RTL-SDR and LNA is sufficient to detect the hydrogen line peak and doppler...

www.rtl-sdr.com

A Hydrogen Line Telescope Made from Cereal Boxes and an RTL-SDR

SpaceAustralia.com have recently been hosting a community science project that involves encouraging teams to build backyard radio telescopes that can detect the arms of our Milky Way Galaxy by receiving the Hydrogen line frequency of 1420 MHz. This can be achieved at home by building a horn...

www.rtl-sdr.com

 

[Channel Hopper]

I'm surprised they suggest a dedicated wifi antenna (looks like a Gabriel antenna design) when any parabolic reflector with a dipole cut to the right frequency and stuck at the focal point will work.

I have a set of exhaust baffles for the motorcycle in the house (for MOT passes) consisting of threaded bar and 28mm washers at strategic points, which I suppose could be used once upscaled to provide the right band for reception. Similar to that pictured (MMDS detector with LO of 1838MHz)

The longer it is the more directional it becomes, adding more washers and spacers.


Chaparral made a triband corotor years ago that included an S-band dipole in the scalar rings, I'll dig it out from the shed at some point

 

[Channel Hopper]

Then again grid antennas are quite cheap direct from the manufacturers.

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[PaulR]

Minimum order 1000 though!

 

[Channel Hopper]

My error

Gabiel took the Mark antenna brand and their P15/17/20 range under its wing, before being copied worldwide.

Data Sheets for the Mark Grid Antenna Line

Mark Grid Antenna data sheets are offered as a supplement to the electrical specifications found on this website.

markgridantenna.com

 

[Terryl]

Any antenna that is a 5/8, 1/2 or 1/4 wavelength of the desired radio frequency would work, it can also be 2, 4 or 8 times larger.

What has been done is to use a high gain UHF TV antenna and mount it to the center of an old 10 foot satellite dish, the dish was X/Y steerable with a Yaesu ham satellite rotor, 710 MHz (half wave of 1420 MHz) is on the upper end of most older UHF TV antennas, and they work quit well as a 1/2 wave receive antenna.

We tried this years ago at a CATV down-link site I worked at, (lots of time on your hands on the night shift) but found that the local RF jumble from the surrounding city caused too much interference.

If your going to try this I would suggest a very remote location, or a location shielded by hills or mountains, I wish I still had the hardware as my current location would be ideal.

 

[Terryl]

If you got the cash, here is a site that sells feed-horns and LNA's for the 1420 MHz band.

Radio2Space radio telescopes and ground station antenna systems

We create advanced and affordable radio telescopes for radio astronomy and ground station antenna systems for space communication.

www.radio2space.com

 

[Terryl]

If your trying to listen to something in the Hydrogen band, then try for this one.......https://www.sciencealert.com/periodicity-has-been-detected-in-a-repeating-fast-radio-burst

It's around 1400 MHz, and comes around every 16 days or so.