Series coax stub capacitors for more precise loop antenna tuning

I recently build a loop antenna and used a RG58 coax stub as capacitor.

While cutting the stub to length while checking with a NanoVNA for SNR i noticed that even very small size reduction of the stub (+-1mm) could make the resonance frequency of the loop jump up and down 40-50kHz.

Since the channels on CB radio are only 10kHz wide that made tuning the loop to a channel difficult because it turns out clipping sub millimeter of the end of a coax aint easy.

After a bit of thinking of how i could lower the capacitance of the RG58 coax i realized i could just take 2 lengths of RG58 and put em in series, since putting capacitors in series reduces there capacitance.

This increased the size of the coax stub quite a bit (see picture compared to old coax stub).

But it worked very well, now clipping of about 3mm of one of the coax ends will result in about 10kHz change of loop tuning, hence the precision was increased a lot and i was finally able to tune into the precise channel i wanted.