Interesting antenna experience: With my Tino (
https://lowpowerlab.com/forum/index.php/topic,1269.0.html) I've been experiencing sub par RF performance. RSSI was about 10-12 lower than with a regular Moteino with 9V battery.
I did some research and some experiments and found that:
1.) The Tino had great RF performance if powered from a cylindrical Lithium battery.
2.) Different environments (e.g. sizes of ground plane) sometimes lead to very significant resonance shifts.
3.) Resonance shifts can be compensated for by adjusting antenna length.
So I hooked a 25cm antenna to my 433mhz Tino and started clipping. Turns out the optimal antenna length with CR2450 mounted is 22-23cm instead of the around 17cm that work for a Moteino. At that length RF performance is similar to a Moteino with 9V battery. I would have never expected such a large divergence.
So if you've built elaborate enclosures etc and get RF problems, just attach a LONG antenna and take out your scissors.