01-30-2009, 08:14 AM
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Join Date: Dec 2008
Location: United Kingdom
Fair enough - but a couple points about the helical antenna: you get conventional mode and you get axial mode helical antennas - so take note as follows.
1) its only helicals in axial mode that will give you extended transmission and reception distances - and make sure that they are either both right hand twists to the helix coil, or both left hand tesists to the helix coil. if one is left hand and the other is right hand, you will loose approx 50% of the signal strength.
2) as for multi - path reflection reception you really need to use the helical in conventional mode - not axial mode.
3) any LNA connected to a card will fry it? Not true. Just make sure you choose an LNA that does not exceed the cards max db or dbi input, and if it does, purchase an in-line attenuator of the corrrect attenuation. I see where this is going, and quite frankly in this case you are going to be better off not with attentuation of any LNA, but with a higher gain receive antenna, and if that isn;t any good, then adding filtering - consider a low band pass filter with a steep roll-off (they are not cheap!).
Start talking about attenuators and LNA's and you are getting into the realms of lots of money, and a whole bunch of tecnical issues that are usualy well beyond the tech scope of the average DIY'er to assess correctly and accurately.
My advise (unless you are a tec geek) - KISS Keep It Simple Stupid.