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Topic Title: Matching transmission losses on Solid State Power Amplifier
Topic Summary: Should you add the matching transmission losses back in when calculating Worse Case Maximum power of a SSPA
Created On: 15 January 2013 01:08 PM
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 15 January 2013 01:08 PM
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Joined: 15 January 2013

This is a weird way of looking at matching losses so I want to confirm I am looking at this properly. Normally you would look at it as reducing RF output power.
I have tuned my solid state power amplifier (SSPA) so I have a pretty good match (1.5:1 worse case). The antenna it is connected to has a 2:1 mismatch. Now this is were it gets interesting; we only made power output measurements with a 2:1 sliding load connected to the output and rotated the angle of the load to get a minimum output power measurement. Let's say that measurement is 30dBm. Someone wants to know what the theoretical maximum power of the SSPA could be based on this minimum measurement because we can't retake the measurement to find the angle at which the maximum power is produced. Keep in mind the output of the SSPA has an isolator so the active devices are fairly well isolated from the load and don't get pulled around during the rotation of the angle.
Here are my thoughts:
1) The 2:1 mismatch has a transmission loss of 0.51dB
2) The 1.5:1 mismatch of the SSPA has a transmission loss of 0.18dB

When we made the first measurement we intentionally rotated the angle of the load to find the worse case match or minimum Pout point. If you connect a 2:1 sliding load again is it correct to say that you could theoretically find a match that would produce a power output of 30dBm + 0.51dB + 0.18dB = 30.69dBm?

Can you explain either way?

Thank you ahead of time for any help you can provide.

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