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