# Wavelength vs Frequency

This page on wavelength vs frequency describes difference between wavelength and frequency.

Where, λ = Wavelength in meters
F = Frequency in Hertz
ε = Dielectric constant of propagation medium
c = velocity of light, i.e. 3 x 108 m/s

Frequency is the term usually refers to number of cycles of the Electro-Magnetic wave per second. It will be specified that radio or wireless system works at so and so frequency etc. Wavelength mainly determine the size of the antenna. Lower the frequency higher the wavelength and higher the frequency lower the wavelength. Lower wavelegth help concentrate narrow region and higher the wavelength help concentrate broader region of the earth or area. Usually for communication from satellite to ground(point to multi-point link) wavelength should be higher to cover more area and for communication from ground to the satellite(point to point link) wavelength should be lower to point to the receiving system.

The wavelength of the microwave signal varies from 75cm(at 400MHz) to 1mm(at 300GHz). Due to this frequencies above 20GHz are referred as millimeter wave frequencies.

Dielectric constant of the medium has got lot of effect on the relationship between frequency and the wavelength. Dielectric constant(ε) is property of the medium where in the EM wave propagates. ε for perfect vaccum is 1,for dry air 1(approx. 1.006) and for teflon about 2-11.

The wavelength of the 18GHz microwave signal in the air as medium is 0.17m and for teflon it is anout 0.0053m. Hence it is understood that changing the medium will have considerable effect on the wavelength.