How so? People add 20-plus dB LNAs next to their antennas very often to put the gain near the antenna and improve linearity and the S/N ratio. It would seem to me that using an antenna with more gain would accomplish sort of the same thing to a lesser extent as there are no 20dB gain antennas that I’m aware of.
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We are talking about the difference of an antenna 5dBi vs. 7.5dBi, not an additional filtered LNA
I was just saying that over time, both antennas delivered the same results.
An antenna 20dBi would not accomplish the same as a filtered LNA because also the noise would be higher
Comparing the gain increase by antenna design with gain increase by LNA is not a fair comparison.
As the gain of antenna increases with change in it’s design, it’s radiation pattern is also quashed. On the other hand, the LNA increases the gain only, it does not change radiation pattern.
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Oh yeah, I forgot about that. I was just thinking in terms of dBs of gain, not about the radiation patterns necessary to achieve that gain. A 7dB gain antenna receives more from the horizons but less from upward so it may possibly sacrifice some performance for nearby aircraft in favor of those far away vs. the 5dB antenna, all else being the same.
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That shouldn’t really be an issue - the vertical pattern is given as 16 degrees for that antenna (though it doesn’t state for what dB range that is). Most aircraft are within 5 degrees of the horizon for the majority of the time and it’s only when they get within 50 miles or so that they’d be outside the radiation pattern of that antenna, but it’s not like a sharp cut off where nothing is received. ADS-B uses quite powerful transmitters so signal strength is unlikely to be a problem. If anything slightly reduced sensitivity for close range targets is actually useful because it means a strong signal is less likely to overload the receiver or LNA input.
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Yes, there is that. (20 characters)
@keithma sweet looking set up that is, may I ask where you sourced the waterproof enclosure from as I want to get my 2nd feeder up on the TV mast and looking to have only 30-50cm coax from aerial to dongle. Also what PSU are you using as I need to look for one that I could use over a 25m cable run.
Thanks, we’re using a box like this and the PSU is one of the LM2596 DC-DC converter modules you can get on eBay cheaply.