in that article,
said...

300,000 KM / 27,000,000 = 11.11111 metre

the best length of antenna is 1/2 of the wave length. 5.56 m

but that is too long for rc cars.
so take 1/32 for 1:10 that is 34cm

for mini Z 1/64 will be 17cm for best reception...

however i have no idea where the 300,000 km comes from....