Understanding Antennas & Radio Waves: Fields, Wavelength, & Angle, Slides of Physics

Download Understanding Antennas & Radio Waves: Fields, Wavelength, & Angle and more Slides Physics in PDF only on Docsity! Antennas Docsity.com Free Charge  A free charge has a constant electric field and no magnetic field.  No waves are produced. • No radiation  A charge at constant velocity has both fields. • Fields are constant so no wave forms. B field surrounds electric field, although there is no “current” flowing here Docsity.com Angled Antenna  The conductor works best when parallel with the electric field.  At an angle the effective field is reduced. θcosEEeff = Docsity.com Radio Waves  Radio waves are a type of electromagnetic wave.  Broadcast antennas put out electric and magnetic fields. Docsity.com Wavelength  A radio station broadcasts FM signals at 93.9 MHz.  Find the wavelength of the electromagnetic wave.  First assume that the speed is the speed in a vacuum c.  The speed of a wave is related to the wavelength and frequency. • v = λf  Solve for the wavelength. • Speed of light • Frequency f = 9.39 x 107 /s • λ = c/f • λ = 3.19 m  Antennas should be slightly shorter than size to work well. next Docsity.com