Bifilar helix (backfire)

[clanon 248]

Starting point this site by Graham Sharples 

13 cm bifilar helix

I'd never found a good feed for DEEP DISHES ( i have a 1,26 m , 0.31 m deep dish F/d 0.25  )

Edited November 25, 2020 by clanon

[clanon 248]

What's most important to me are the 180 degrees of illumination at about -6 db of gain...

helix length – 13cm, 1.5mm wire ,5 doble turns instead of 4 on original site

 -6dB beamwidth of around 180 deg (good for f/D ratios 0.25 (focal plane dishes) to 0.3)

-6dB in beamwidth corresponds  to a -10dB edge illumination (max gain) since there is an additional -4dB spreading loss to the edge at these low f/D ratios.

[Admin 2561]

,,, Clanon, display the dimensions please .. !!!!

[clanon 248]

Adjusted at 2.437ghz center CH 6

can't run the parabolic dish, too big...i dunno how the dish would change this results...(yet)

Edited November 29, 2020 by clanon

[clanon 248]

[Admin 2561]

,,,why do not you try metal disk loaded helical antenna...???

[clanon 248]

...blockage , 180 degrees at -6db illumination...efficiency...