How can this 160MHz VHF locator tag work with such small antenna?
We designed something like this in the mid 70's for Polar Bear tracking beacons for scientists to study migration patterns.
It consists of an LC series tuned current resonator with enough bandwidth for narrow band increase of SNR in the Rx.
It pulsed very slowly with a narrow width to conserve the battery and of course had to be bear-proof.
The solid coaxial wire loop made the inductance stable and low impedance while the maximum signal vs f was tuned with the ceramic trimcap.

Here I choose a resistance that would represent the transistor switch Rce which indicates the max power with low losses on this transfer function. The tradeoffs are Q, loss and stability from bear motions.  Temperature compensation for the small NTC of copper required a PTC cap in parallel with the trim cap.
Tracking was usually done by aerial surveys with a directional Yagi.