how do i make sure crystal oscillator module only produces radio waves when an a

i am planning to build a radio transmitter. i connect a 100 mhz crystal oscillator to a battery. if i connect the 100 mhz crystal oscillator module on a breadboard to a battery and there is no antenna, it will still produce radio waves. if i use a perfboard instead of a breadboard, will the crystal oscillator module only produce radio waves when i attach an antenna?