Signal attenuation (loss) for common coaxial cables at around 1.42 GHz (1420 MHz), relevant for builders of amateur Hydrogen Line radio telescopes.

[andrew....@googlemail.com]

I have tried to draw up a comparison of loss on different coaxial cables at the hydrogen line and posted it on my website – thoughts welcome! (especially anywhere where I need to modify it or correct it).

 

https://www.astronomy.me.uk/16261-2

 

Andy

[fasleitung3]

Thanks Andy,

An additional good option is Aircell 7. It is just a little bit thicker than LM240 but has lower attenuation. It also is quite a bit cheaper than LM240. We use it in all cases where we need a bit of flexibility of the cable. Other than that we use mostly Ecoflex 10 which is very comparable to LM400.

Best regards,

Wolfgang

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[James Abshier]

Your table shows a loss for RG6 of 15 - 20 dB/100ft. Most information I have seen has it as about 7 - 8 dB/100ft.

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[Alex P]

LNAs should be  " positioned close to the waveguide "   regardless of the coax.

                                   

from your webpage :

Cheaper cables, such as RG-6, can be used as long as there is filtering and amplification at the masthead (just behind the waveguide)

 using a low power amplifier and filter such as the Nooelec SAWBird H1+ LNA. 

However, this MUST be positioned close to the waveguide and not at the other end of the coaxial cable near the software defined radio (SDR).

[b alex pettit jr]

Microwaves101 | Noise Figure

Microwaves101 | Noise Figure Microwaves101 | Noise Figure

[andrew....@googlemail.com]

Thanks Wolfgang – I have updated the post to reflect this and correct RG58 attenuation.

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[andrew....@googlemail.com]

I have made this correction to the webpage, Alex – thanks for the suggestion.

Andy

 

From: 'Alex P' via Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Sent: 07 February 2026 11:39
To: Society of Amateur Radio Astronomers <sara...@googlegroups.com>
Subject: Re: [SARA] Signal attenuation (loss) for common coaxial cables at around 1.42 GHz (1420 MHz), relevant for builders of amateur Hydrogen Line radio telescopes.

 

LNAs should be  " positioned close to the waveguide "   regardless of the coax.

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[Andrew Thornett]

Thanks James for noticing the error on attenuation RG6 on the table on my website - is have corrected this now.

Andy

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From: sara...@googlegroups.com <sara...@googlegroups.com> on behalf of James Abshier <abs...@ameritech.net>
Sent: Friday, February 6, 2026 6:37:24 PM
To: sara...@googlegroups.com <sara...@googlegroups.com>

Subject: Re: [SARA] Signal attenuation (loss) for common coaxial cables at around 1.42 GHz (1420 MHz), relevant for builders of amateur Hydrogen Line radio telescopes.

 

Your table shows a loss for RG6 of 15 - 20 dB/100ft. Most information I have seen has it as about 7 - 8 dB/100ft.