For the 2nd installation I used a salvaged WIFI 5dB antenna, mounted on a external SMA-connector type WIFI antenna kit - see items below. Works great and the solution does not cost "an arm-and-leg"😁
Had previously bought the following USB powered FM signal amplifier, as part of a antenna kit, to overcome the loss of access to the building FM antenna facility (REF: http://myoldvintagehifi.blogspot.com/2019/02/alternate-analogue-fm-reception-for.html)
I can definitely recommend this USB powered FM signal amplifier as it is works very well and is a cost effective solution. Even bought a 2nd unit for another tuner in the house!
It is basically the no-frills version of the FM signal amplifier which was originally intended for use in motor vehicles but altered to draw power via USB. Hence there is no need to buy the expensive radio signal amplifiers or antenna kit as the total cost for all the items in the pix(s) below cost less than the price for a single signal amplifier unit (only) at the local shops!
Note - May need to purchase connector adapter(s) to enable connectivity and an external antenna