I think you meant RG6. RG59's high frequency response kills the UHF frequencies of SWM channels more per foot than RG6, so for equal performance, RG59 won't go as far.
From
[Link: sewelldirect.com]:
RG6 has a signal loss of 6.8 dB per hundred feet at 900 MHz
RG59 has a signal loss of 11.1 dB per hundred feet at 900 MHz