T9B: Propagation, fading, multipath distortion, reflections, radio horizon, terrain blocking, wavelength vs. penetration, antenna orientation
T9B01:
Why are VHF/UHF signals not normally heard over long distances?
VHF and UHF signals are usually not reflected by the ionosphere
They are too weak to go very far
FCC regulations prohibit them from going more than 50 miles
They collide with trees and shrubbery and fade out
T9B02:
What might be happening when we hear a VHF signal from long distances?
A possible cause is sporadic E reflection from a layer in the ionosphere
Signals are being reflected from outer space
Someone is playing a recording to us
Signals are being reflected by lightning storms in our area
T9B03:
What is the most likely cause of sudden bursts of tones or fragments of different conversations that interfere with VHF or UHF signals?
Strong signals are overloading the receiver and causing undesired signals to be heard
The batteries in your transceiver are failing
The receiver is picking up low orbit satellites
A nearby broadcast station is having transmitter problems
T9B04:
What is the radio horizon?
The point where radio signals between two points are blocked by the curvature of the Earth
The distance from the ground to a horizontally mounted antenna
The farthest point you can see when standing at the base of your antenna tower
The shortest distance between two points on the Earth's surface
T9B05:
What should you do if a station reports that your signals were strong just a moment ago, but now they are weak or distorted?
Try moving a few feet, random reflections may be causing multi-path distortion.
Change the batteries in your radio to a different type
Speak more slowly so he can understand your better
Ask the other operator to adjust his squelch control
T9B06:
Why do UHF signals often work better inside of buildings than VHF signals?
The shorter wavelength of UHF signals allows them to more easily penetrate urban areas and buildings
VHF signals lose power faster over distance
This is incorrect; VHF works better than UHF inside buildings
UHF antennas are more efficient than VHF antennas
T9B07:
What is a good thing to remember when using your hand-held VHF or UHF radio to reach a distant repeater?
Keep the antenna as close to vertical as you can
Speak as loudly as possible to help your signal go farther
Keep your transmissions short to conserve battery power
Turn off the CTCSS tone
T9B08:
What can happen if the antennas at opposite ends of a VHF or UHF line of sight radio link are not using the same polarization?
Signals could be as much as 100 times weaker
The modulation sidebands might become inverted
Signals have an echo effect on voices
Nothing significant will happen
T9B09:
What might be a way to reach a distant repeater if buildings or obstructions are blocking the direct line of sight path?
Try using a directional antenna to find a path that reflects signals to the repeater
Change from vertical to horizontal polarization
Ask the repeater owners to repair their receiver
Transmit on the repeater output frequency
T9B10:
What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting?
Picket fencing
Flip-flopping
Frequency shifting
Pulsing
T9B11:
Why do VHF and UHF Radio signals usually travel about a third farther than the visual line of sight distance between 2 stations?
The Earth seems less curved to radio waves than to light
Radio signals move somewhat faster than the speed of light and travel farther in the same amount of time
Radio waves are not blocked by dust particles
Radio waves are blocked by dust particles
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● = Incorrect answer
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