Term
| T3A01 What should you do if another operator reports that your stations 2 meter signals were strong just a moment ago, but now they are weak or distorted? |
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Definition
| Try moving a few feet, as random reflections may be causing multi-path distortion |
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Term
| T3A02 Why are UHF signals often more effective from inside buildings than VHF signals? |
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Definition
| The shorter wavelength allows them to more easily penetrate the structure of buildings |
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Term
| T3A03 What antenna polarization is normally used for long-distance weak-signal CW and SSB contacts using the VHF and UHF bands? |
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Definition
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Term
| T3A04 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? |
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Definition
| Signals could be significantly weaker |
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Term
| T3A05 When using a directional antenna, how might your station be able to access a distant repeater if buildings or obstructions are blocking the direct line of sight path? |
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Definition
| Try to find a path that reflects signals to the repeater |
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Term
| T3A06 What term is commonly used to describe the rapid fluttering sound sometimes heard from mobile stations that are moving while transmitting? |
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Definition
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Term
| T3A07 What type of wave carries radio signals between transmitting and receiving stations? |
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Definition
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Term
| T3A08 What is the cause of irregular fading of signals from distant stations during times of generally good reception? |
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Definition
| Random combining of signals arriving via different path lengths |
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Term
| T3A09 Which of the following is a common effect of "skip" reflections between the Earth and the ionosphere? |
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Definition
| The polarization of the original signal is randomized |
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Term
| T3A10 What may occur if VHF or UHF data signals propagate over multiple paths? |
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Definition
| Error rates are likely to increase |
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Term
| T3A11 Which part of the atmosphere enables the propagation of radio signals around the world? |
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Definition
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Term
| T3B01 What is the name for the distance a radio wave travels during one complete cycle? |
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Definition
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Term
| T3B02 What term describes the number of times per second that an alternating current reverses direction? |
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Definition
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Term
| T3B03 What are the two components of a radio wave? |
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Definition
| Electric and magnetic fields |
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Term
| T3B04 How fast does a radio wave travel through free space? |
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Definition
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Term
| T3B05 How does the wavelength of a radio wave relate to its frequency? |
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Definition
| The wavelength gets shorter as the frequency increases |
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Term
| T3B06 What is the formula for converting frequency to wavelength in meters? |
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Definition
| Wavelength in meters equals 300 divided by frequency in megahertz |
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Term
| T3B07 What property of radio waves is often used to identify the different frequency bands? |
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Definition
| The approximate wavelength |
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Term
| T3B08 What are the frequency limits of the VHF spectrum? |
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Definition
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Term
| T3B09 What are the frequency limits of the UHF spectrum? |
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Definition
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Term
| T3B10 What frequency range is referred to as HF? |
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Definition
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Term
| T3B11 What is the approximate velocity of a radio wave as it travels through free space? |
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Definition
| 300,000,000 meters per second |
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Term
| T3C01 Why are "direct" (not via a repeater) UHF signals rarely heard from stations outside your local coverage area? |
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Definition
| UHF signals are usually not reflected by the ionosphere |
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Term
| T3C02 Which of the following might be happening when VHF signals are being received from long distances? |
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Definition
| Signals are being refracted from a sporadic E layer |
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Term
| T3C03 What is a characteristic of VHF signals received via auroral reflection? |
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Definition
| The signals exhibit rapid fluctuations of strength and often sound distorted |
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Term
| T3C04 Which of the following propagation types is most commonly associated with occasional strong over-the-horizon signals on the 10, 6, and 2 meter bands? |
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Definition
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Term
| T3C05 What is meant by the term "knife-edge" propagation? |
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Definition
| Signals are partially refracted around solid objects exhibiting sharp edges |
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Term
| T3C06 What mode is responsible for allowing over-the-horizon VHF and UHF communications to ranges of approximately 300 miles on a regular basis? |
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Definition
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Term
| T3C07 What band is best suited to communicating via meteor scatter? |
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Definition
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Term
| T3C08 What causes "tropospheric ducting"? |
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Definition
| Temperature inversions in the atmosphere |
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Term
| T3C09 What is generally the best time for long-distance 10 meter band propagation? |
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Definition
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Term
| T3C10 What is the radio horizon? |
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Definition
| The distance at which radio signals between two points are effectively blocked by the curvature of the Earth |
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Term
| T3C11 Why do VHF and UHF radio signals usually travel somewhat farther than the visual line of sight distance between two stations? |
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Definition
| The Earth seems less curved to radio waves than to light |
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