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Tech Head - The Technology Section
SDR radio, Software Defined Radio
Antenna thread
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<blockquote data-quote="s-band" data-source="post: 972639" data-attributes="member: 407744"><p>Use the software switch in SDR# to enable/disable LNA</p><p>Here's my offset feed</p><p>[ATTACH]93553[/ATTACH]</p><p></p><p>Assuming Airspy NF = 4dB</p><p>Cable loss = 14 dB</p><p>LNA gain 15dB NF 1dB</p><p>Cascade NF is 5.08dB</p><p>So you will have a worse S/N than with the SDR near the antenna.</p><p></p><p>Increase LNA gain to 30dB with everything else the same and the cascade NF is 1.21dB</p><p>Play with different configurations using <a href="http://www.hp.woodshot.com/appcad/appcad.htm" target="_blank">AppCAD Download</a></p><p></p><p>Matching about 2mm above ground but see post #107 above</p><p>Anything from the SMA on can affect it.</p><p>You could try a dipole with reflector, that should only be 3-4dB down on circular.</p></blockquote><p></p>
[QUOTE="s-band, post: 972639, member: 407744"] Use the software switch in SDR# to enable/disable LNA Here's my offset feed [ATTACH]93553[/ATTACH] Assuming Airspy NF = 4dB Cable loss = 14 dB LNA gain 15dB NF 1dB Cascade NF is 5.08dB So you will have a worse S/N than with the SDR near the antenna. Increase LNA gain to 30dB with everything else the same and the cascade NF is 1.21dB Play with different configurations using [URL='http://www.hp.woodshot.com/appcad/appcad.htm']AppCAD Download[/URL] Matching about 2mm above ground but see post #107 above Anything from the SMA on can affect it. You could try a dipole with reflector, that should only be 3-4dB down on circular. [/QUOTE]
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