Table of Contents
- 1 What are the three important radio propagation phenomena at high frequencies?
- 2 Why are direct UHF signals rarely heard from stations outside your local coverage area?
- 3 How does the wavelength of a radio wave relate to its frequency?
- 4 What type of wave propagation is used in VHF UHF and microwave signals?
- 5 What is tropospheric ducting?
- 6 What is sporadic E layer?
- 7 What is UHF and VHF?
- 8 What frequency is UHF?
- 9 Why are UHF and VHF signals greater in the winter?
- 10 What causes the total signal to fade over time?
What are the three important radio propagation phenomena at high frequencies?
In general, radio wave propagation consists of three main attributes: reflection, diffraction and scattering (see Figure 3.1) [2]. Reflection occurs when radio wave propagating in one medium impinges upon another medium with different electromagnetic properties.
Why are direct UHF signals rarely heard from stations outside your local coverage area?
Why are direct (not via a repeater) UHF signals rarely heard from stations outside your local coverage area? Any time you hear stations directly (not using a repeater system) from far away, you can assume some sort of atmospheric condition is helping the signal to travel.
How does the wavelength of a radio wave relate to its frequency?
The frequency is the number of cycles per second; thus, if you have more cycles in the same distance (higher frequency), the distance between peaks (wavelength) will be shorter.
What are the frequency limits of the VHF spectrum?
Very high frequency
| Frequency range | 30 MHz to 300 MHz |
|---|---|
| Wavelength range | 10 to 1 m |
How does UHF propagate?
UHF radio waves propagate mainly by line of sight; they are blocked by hills and large buildings although the transmission through building walls is strong enough for indoor reception.
What type of wave propagation is used in VHF UHF and microwave signals?
VHF, UHF, Microwaves and Millimeter Waves Radio wave propagation in the frequency range above 30 MHz occurs essentially by direct antenna-to-antenna space waves. This is usually called line-of-sigh (LOS) communications.
What is tropospheric ducting?
Tropospheric ducting is a type of radio propagation that tends to happen during periods of stable, anticyclonic weather. This is termed a temperature inversion, and the boundary between the two air masses may extend for 1,000 miles (1,600 km) or more along a stationary weather front.
What is sporadic E layer?
Sporadic E (Es) layers are narrow layers with high electron densities consisting mainly of metallic ions. These layers appear sporadically in the region predominantly at altitudes between 90 and 120 km.
What type of radiation are VHF and UHF radio signals?
Lower frequency radiation, which includes all amateur radio frequencies, is non-ionizing. Regardless of the power of the signal, the frequecies of VHF and UHF signals are too low to dislodge the electrons. (Gamma and alpha radiation are both ionizing radiation.)
What may occur if data signals arrive via multiple paths?
What may occur if data signals arrive via multiple paths? When the same signal propagates over multiple paths the different paths will generally be a slightly different distance and different angles. When the signal is a data signal, this distortion causes information loss leading to higher error rates.
What is UHF and VHF?
Every wireless microphone system transmits and receives on a specific radio frequency, called the operating frequency. VHF = “Very High Frequency”. UHF = “Ultra High Frequency.” The FCC also determines who can operate in each band and who has priority if more than one user is operating.
What frequency is UHF?
3,000 and 300 megahertz
UHF, abbreviation of ultrahigh frequency, conventionally defined portion of the electromagnetic spectrum, encompassing radiations having a wavelength between 0.1 and 1 m and a frequency between 3,000 and 300 megahertz.
Why are UHF and VHF signals greater in the winter?
The range of VHF/UHF signals could be greater in the winter due to less absorption by vegetation. This is the only option that is clearly correlated with winter and applies to VHF and UHF.
What happens when signal propagates over multiple paths?
When the same signal propagates over multiple paths the different paths will generally be a slightly different distance and different angles. As a result, the signal arrives at the destination from multiple directions at multiple times.
What causes radio waves to travel in different paths?
Multipath distortion is caused by radio waves bouncing off of different objects (mountains, large buildings, etc) and then all arriving at the same location but having traveled a different distance. Because of this they arrive at slightly different times (having traveled at different, or multiple, paths) and can interfere with each other.
What causes the total signal to fade over time?
When these signals all arrive, with some taking longer than others, they can combine in such a way that it can cause the total signal to fade such as when the signal along one path is (or close to it) out of phase with another causing the waves to cancel each other out.