It's not a matter of distance that determines how wide the antenna is, it's the frequency. VHF channels operate on lower frequencies, so wider elements are needed, for the resonant frequency. It's like organ pipes; the low notes need longer pipes.
It is difficult to predict the strength of indoor signals, but many people have had good results with the Antennas Direct C2V. The "V" dipole attachment is for VHF-High.
An alternative for better reception of NBC is to combine (with a UVSJ) the output of your UHF antenna with an Antennas Direct C5 VHF-High antenna that has more gain than the dipole of the C2V.
Or, if you are handy with DIY, you can make a folded dipole for NBC.
http://users.wfu.edu/matthews/misc/dipole.html
WXIA NBC, real channel 10, 192 to 198 MHz
center frequency 195 MHz
5540/195 = 28.4 inches wide for channel 10