If it were not for the effects of diffraction, a 2" aperture telescope could theoretically be used to read newspapers on a planet circling Alpha Centauri, over four light-years distant.
Ultra high frequency | Frequency modulation | frequency | High frequency | Very high frequency | Spatial anti-aliasing | frequency modulation | Extremely high frequency | Radio-frequency identification | Medium frequency | Frequency | Cambridge Low Frequency Synthesis Telescope | ultra high frequency | Super high frequency | low frequency | Frequency Modulation | Frequency-division multiplexing | FreQuency | Utility frequency | Spatial Query Server | Railroad cutoff | Orthogonal frequency-division multiple access | Nyquist frequency | Modified Frequency Modulation | Meek's Cutoff | Low-frequency oscillation | Low-frequency effects | Low frequency | Living on Another Frequency | High Frequency Active Auroral Research Program |