# Definitions

**Aliasing:****The sampling of a magnitude VS time whose interval makes a false repetition, and an inability to analyze data at that interval.**

**Antenna:****A device used to radiate or receiving radio waves.**

**ASICs:****Application Specific Integrated Circuit.**

**Bandwidth:****The start and stop frequency delta.**

**Capacitance:****The ratio of the charge on one of the conductors of a capacitor to the potential difference between the conductors.**

**Clock frequency:****The master frequency of the periodic pulses that schedule the operation of a computer.**

**Common mode:****The same amplitude and phase at both inputs of a balanced transmission line. The energy imparted to ground when a balanced transmission line is not ideal.**

**Cross Talk:****The measured unwanted coupling from one channel and another.**

**Current:****The net transfer of electric charge per unit time. The rate of flow across a surface per unit time.**

**Cutoff Frequency:****is the place where the wavelength is able to fit once in the transmission line.**

**DC:****Electric current that flows in one direction only.**

**AC:****Electric current that reverses direction periodically, many times per second.**

**dB:****The ratio of 2 magnitudes. Also the ratio of a power to reference power.**

**Electrical length:****Unit of time required to travel in a transmission line.**

**EMC:****Unwanted coupling that occurs between circuits.**

**EMI:****Interference at high frequencies causing unwanted disturbance to other systems.**

**Energy:****Measured in milliwatts. Differences expressed in dB.**

**EYE Pattern:****A specific plot denoting skew, Tr, skin effect, jitter, cross talk, insertion loss, resistance, common mode, simultaneously. (Other masks besides EYE are also common)**

**Frequency:****The number of cycles completed by a periodic quantity in a unit time.**

**Field lines:****A topological arrangement of electric and magnetic fields.**

**Gain:****The increase in signal power.**

**Gating:****To selectively pre-select a window of the magnitude VS time interval for close inspection used in a Fourier series to remove unwanted disturbances**

**Ground:****Electrical connection to a reference conducting plane. Provide a return path in a transmission system.**

**Group Delay:****The measured envelope of time VS frequency of a transmission line.**

**Impedance:****The AC characteristics of real and imaginary components.**

**Impedance matching:****Where the transmission line and the source are going to have minimum reflections and minimum distortions.**

**Inductance:****The ratio of the electromotive force to the rate of change of the current.**

**Insertion Delay:****The measured time it takes for a signal to pass completely through a transmission line usually referenced to the 50% points.**

**Insertion Loss:****The loss in power received at the load due to the transmission line.**

**Launch:****The transfer point where energy transfers from one point to another.**

**Loss Tangent:****Energy lost in the dielectric partially due to the slower propagation compared to air.**

**Magnetic waves:****perpendicular to the electric wave.**

**Mismatch:****The impedance of the source does not match the impedance of the transmission line.**

**Reflection:****A discontinuity caused by a wave traveling back into the source.**

**Resistance(DC):****The opposition that a material offers to the flow of direct current, equal to the voltage drop across the material divided by the current through the material.**

**Resistance(AC):****The real part of the complex impedance.**

**Resonance:****The frequency at which there is a sharp peak of power when a circuit contains inductance, capacitance, and resistance of specific values.**

**Return Loss:****The ratio between the incident power upon a discontinuity and the power reflected from the discontinuity.**

**Ringing:****A cyclic arrangement of alternating transients that are under damped but decreasing over time in amplitude and period.**

**Rise Time:****The transition time (usually 10% to 90%) when a signal is suddenly applied from a well-behaved source to a transmission line.**

**Shielding:****A conductive barrier.**

**Shielding effectiveness:****How much energy can be radiated.**

**Sine waves:****A wave whose amplitude varies as the sine of a linear function of time.**

**Skew:****The delta in time of the signal traveling through more than one transmission line.**

**Skin effect:****The layer of the center conductor at which all the current is carried at a specific frequency.**

**Spectrum:****The distribution of energy distributed over frequency.**

**SWR:****The ratio of maximum amplitude to the minimum amplitude of a wave in a transmission line. (Standing Wave Ratio.)**

**TEM:****Transverse electric, magnetic. Particular waves are propagated. Electric waves; transverse.**

**TDR:****Time Delay Reflectometry.**

**TDT:****Time Delay Through.**

**Transition:****An engineered launch for least disturbance of energy.**

**Transmission:****The transfer of a signal from one location to another.**

**Transmission Line:****A system by which signals can be transferred between 2 or more points.**

**Velocity of propagation:****The speed at which a signal passes through a transmission line with respect to air.**

**Voltage:****Potential difference. Electromotive force. The difference in electric potential between 2 dissimilar nodes connected by a conductor.**

**Wavelength:****The distance between 2 points having the same phase in 2 consecutive cycles in a periodic wave along a line in the direction of propagation.**

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