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HF Propagation

HF Propagation. Direction of Maximum Radiation. h. 300-350 km. F2: Separate during daylight, merge w/F1 at night. F1: Separate during daylight. 250 km. Propagation in the Atmosphere. E: Daylight Only, Ultraviolet Radiation. Ionospheric Layers. 140 km.

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HF Propagation

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  1. HF Propagation Direction of Maximum Radiation h

  2. 300-350 km F2: Separate during daylight, merge w/F1 at night. F1: Separate during daylight 250 km Propagation in the Atmosphere E: Daylight Only, Ultraviolet Radiation Ionospheric Layers 140 km D: Daylight Only, Particle radiation 90 km 50 km Presence of ionized particles causes variation in er , leading to reflection/refraction at the boundaries. fv : the frequency below which vertical transmissions are reflected, 4 – 5 Mhz.

  3. “Skip” Commmunication Multi-hop sky wave q1 Line of sight condition: hr ht Skip Zone

  4. Atmospheric Absorption Attenuation

  5. Space Loss/Space Attenuation Spreading Loss Space Attenuation EIRP Space Loss

  6. Use this Equation!! DO NOT use eq 15-43, 15-44, or 15-45 on page 653!! R and l must have the same units! Example: Determine received power if transmitted power is 2 watts, f = 450 Mhz, transmit antenna gain is 12 dB, receive antenna is ¼ wave whip, range is 50 km. =3 dBw + 12 dB – 119.5 dB + 2 dB = -102.5 dBw = -72.5 dBm ( ~56.0 pW)

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