CIT228 Chapter 3 RF Fundamentals
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
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| 10’s and 3’s Rules of RF Math | A shortcut for calculating the increase or decrease of RF values.
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| 180 degrees out of phase | Term used to describe two electromagnetic signals that are the complete opposite of each other.
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| absorption | The RF propagation behavior in which an RF signal is assimilated into a material.
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| amperes (amps) | The measure of the flow of electrical current.
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| amplification | An increase in a signal’s strength to achieve gain.
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| amplitude | The magnitude of the change of a wave; measured by how high or how deep the wave is.
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| amplitude modulation (AM) | A modification of an analog electromagnetic wave that changes the amplitude (height) of the wave.
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| amplitude shift keying (ASK) | A modification of a digital electromagnetic wave that changes the amplitude (height) of the wave.
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| analog signal | A continuous signal with no “breaks” in it.
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| attenuation | Loss of signal strength that results in a decrease in the signal’s amplitude.
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| bands | The 450 different sections of the electromagnetic spectrum.
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| carrier | A modified electromagnetic wave that is used to transmit information. Also known as a carrier wave or a carrier signal.
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| corruption | The loss in a signal that occurs when a delayed multipath signal is significantly out-of-phase with the primary signal.
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| current (I) | The flow of electrical energy.
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| cycle | The repetitive movement of an electromagnetic wave that returns back to its starting point.
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| decibel milliwatt (dBm) | The power ratio in decibels (dB) referenced to one milliwatt (mW).
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| decibels (dB) | The measure used to determine RF power gain and loss on a relative scale.
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| delay spread | The difference in time of multipath signals that reach the receiver.
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| diffraction | The RF propagation behavior in which an RF signal bends in response to striking a rough surface.
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| digital signal | A signal that consists of data that is discrete or separate.
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| downfade | The signal loss that occurs when a delayed multipath signal is out-of-phase with the primary signal
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| electromagnetic spectrum | The range of all the different types of electromagnetic waves.
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| electromagnetic wave | A special form of energy that transmits heat and light.
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| Free space path loss (FSPL) | The “natural” loss of signal strength that occurs as a signal travels through space
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| frequency | The number of times that a wave completes a cycle within a given amount time.
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| frequency modulation (FM) | A modification of an analog electromagnetic wave that changes the frequency (number of waves).
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| frequency shift keying (FSK) | A modification of a digital electromagnetic wave that changes the frequency (number of waves).
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| gain | The positive difference in amplitude between two signals.
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| hertz (Hz) | The unit of measurement for electromagnetic frequencies.
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| impedance | The total amount of resistance to the flow of electrical current.
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| Industrial, Scientific and Medical (ISM) | An unlicensed band used for WLANs.
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| in phase | Two electromagnetic signals that have the same peaks and valleys.
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| license-exempt spectrum | Parts of the radio spectrum that are available nationwide to all users without requiring a license.
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| milliwatt (mW) | One thousandth of a watt of power.
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| modulation | The modification of an electromagnetic wave to transmit information; also called keying
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| multipath | The phenomena in which multiple copies of a signal reach the receiver at different times.
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| nanosecond | One billionth of a second.
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| noise | Unwanted interference that impacts an RF signal.
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| nulling | The cancellation of a signal that occurs when a delayed multipath signal is 180 degrees out of phase with the primary signal.
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| ohms | The measure of the restriction of the flow of current.
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| oscillating signal | The visual representation of up-and-down electrical waves. Also called sine wave.
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| out of phase | Term used to describe two electromagnetic signals with peaks and valleys that do not match.
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| phase | The relationship between at least two signals that share the same frequency yet have different starting points.
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| phase modulation (PM) | A modification of an analog electromagnetic wave that changes the starting point of the wave.
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| phase shift keying (PSK) | A modification of a digital electromagnetic wave that changes the starting point of the wave.
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| Receive Signal Strength Indicator (RSSI) | A value intended for internal use by the wireless NIC.
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| reflection | The RF propagation behavior in which an RF signal bounces back after striking a material.
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| refraction | The RF propagation behavior in which an RF signal bends due to a change in atmospheric condition
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| resistance (R) | Measure of the restriction of the flow of electrical current.
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| scattering | The RF propagation behavior in which an RF signal bounces off small objects, such as raindrops.
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| signal-to-noise ratio (SNR) | A ratio of the desired signal to undesired signal in the average power level of a transmission
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| unlicensed bands | Parts of the radio spectrum that are available nationwide to all users without a license
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| Unlicensed National Information Infrastructure (UNII or U-NII) | An unlicensed band used for WLANs.
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| upfade | The gain in a signal that occurs when the delayed multipath signal arrives at the same time as ad is in phase with the primary signal.
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| voltage (V) | Electrical pressure on a wire.
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| volts | The measure of electrical pressure on a wire.
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| watts (W) | A basic unit of power of 1 amp of current that flows at 1 volt.
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| wavelength | The distance between peaks in an electromagnetic wave.
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| wave propagation | The way in which an electromagnetic signal travels.
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