The big single ears are for the 170-220Mhz band and the smaller multi-ears for 500-700Mhz.
Most of these antennas have sloping attenuation below 500Mhz but fall quickly above 700Mhz.
When they get below their designed 500Mhz limit the directional properties get less and gets more omni directional but will still have some dB gain, especially if you use a mast head amplifier it will compensate and adapt to the antennas impedance mismatch. I have great success with singleband 500-700Mhz tv antennas at 160Mhz compared to a single 160Mhz dipol. You must twist the tv antenna from it's standard horisontal polarisation to a more apropriate vertical installation.