[amsat-bb] Re: Easy to make, low cost omni-directional antennae

[Anthony Monteiro]

At 03:17 PM 3/27/2008, Bill Dzurilla wrote:
>I have just been involved with the sats since February
>and also wanted an omni for base station use
...
>Have not tried the Lindenblad.  Not many are using it
>or talking about it, so I doubt it is all that great.


Dear Friends,

I want to help remove any doubt.

You cannot buy a Lindenblad for the ham bands.
That is a major reason why that they are not so popular.

In terms of performance though, a few data points may
help illustrate. This snapshot is for 2m antennas
mounted at 6' elevation (like I do for field day)

1. At 5 degrees elevation, a Lindy has about 5 dB
    higher gain to satellites with circular polarization
    versus an eggbeater. That is pretty significant if
    you want to work max DX. Of course mounting
    the antennas higher will also help.

2. At 15 degrees elevation, the Lindenblad is only about
    +2 dB higher gain than an eggbeater for circularly polarized
    satellites (mostly insignificant.) But...

3. at the same 15 degrees, on satellites with linearly polarized
    antennas, a Lindenblad will show only about 5 dB max fading from
    polarization mismatch versus nearly 25 dB max fading using
    an eggbeater. That is pretty significant.

So, the eggbeater is probably the best omni antenna you
can buy for working DX on the LEO satellites.

But, in terms of performance, the Lindenblad is a
better antenna if you are willing to build one.


73,
Tony AA2TX