I came across this article in Nature a few days ago where they have tied tiny VHF transmitters to hornets for tracking purposes.
https://www.nature.com/articles/s42003-018-0092-9The article claims a range of "up to 800m". These micro transmitters used a 100mm antenna.
http://www.biotrack.co.uk/pdf/pip_picopip.pdfhttp://www.biotrack.co.uk/pdf/pip.19.pdfThey're using tiny 1.5v silver oxide coin cells. One uses the "AG337" appears to be the same as SR416SW, 8.3mAh in 4.8mm dia by 1.6mm thick. There is another device Pip.19 (12mm x 5mm x 2mm,
http://www.biotrack.co.uk/pdf/pip.19.pdf) that uses an "AG190" cell, but I haven't been able to find any specifications on that one.
The AG337 lifespan is quoted as 12 days days, with a 0.7Hz RF pulse, 20ms pulse width, so a duty cycle of 1.4%. With 8mAh, that suggests about 27uA average current, or at most 2mA when the pulse is active. So output power is ITRO 1mW.
I'm not clear if the pulse is modulated for identification, let's assume not.
So how would you generate 1mW at a reasonably stable frequency at ~150MHz given a 1.5V cell source?