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10 Cards in this Set
- Front
- Back
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What is free space loss? |
Due to the spreading out of the wave front as it travels away from the transmit antenna the receiver antenna catches only a small fraction of the wave front. |
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What is refraction? |
When light penetrates through a substance at a different rate than it does through the surrounding substance. |
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What is reflection? |
The angle of incidence is always equal to the angle or reflection. The incident wave front is reversed by the reflecting surface and appears at 180 degrees out of phase. |
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What is diffraction? |
The bending of a light wave around the edge of a solid object. Generally, lower frequencies diffract more than higher frequencies. |
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What is knife-edge diffraction? |
Is the propagation mode where radio waves are bent around sharp edges. |
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What are two principle radio paths? |
Sky wave and ground waves. |
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What are the four possible routes of a ground wave? |
Direct wave, reflected wave, surface wave, and troposphere wave. |
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What is path loss? |
The reduction in power density (attenuation) of an electromagnetic wave as it propagates through space. Path loss may be due to many effects, such as free-space loss, refraction, diffraction, reflection, aperture-medium coupling loss, and absorption. |
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What is multi-pathing? |
The propagation phenomenon that results in radio signals reaching the receiving antenna by two or more paths. Causes of multipath include atmospheric ducting, ionospheric reflection and refraction, and reflection from water bodies and terrestrial objects such as mountains and buildings. |
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What is anomalous propagation? |
Tropospheric weather phenomena that causes RF energy to propagate in an anomalous or abnormal manner. Wind, air temperature, and water content of the troposphere can combine in many ways, and certain combinations can cause radio signals to be heard hundreds of miles beyond the ordinary range. |
