Electronics (Mike Jaroch)
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H-FIELDAny space or region in which a magnetic force is exerted. The magnetic field may be produced by a current-carrying coil or conductor, by a permanent magnet, or by the earth itself [11]. | ||
H-TYPE T-JUNCTIONA waveguide junction in which the junction arm is parallel to the magnetic lines of force in the main waveguide [11]. | ||
HALF-POWER POINTA point on a waveform or radar beam that corresponds to half the power of the maximum power point [8] [9] [18]. | ||
HALF-WAVE DIPOLE ANTENNAAn antenna, consisting of two rods (1/4 wavelength each) in a single line, that radiates electromagnetic energy [10]. | ||
HALF-WAVE RECTIFIERA rectifier using only one-half of each cycle to change ac to pulsating dc [61 [7]. | ||
HALF-WAVE VOLTAGE DOUBLERTwo half-wave voltage rectifiers connected to double the input voltage [7]. | ||
HAND OVERThe operation where one earth terminal yields control to another as a satellite moves out of its area of coverage [17]. | ||
HARD-TUBE MODULATORA high-vacuum electron tube modulator that uses a driver for pulse forming [18]. | |
HARMONICA frequency that is a whole-number multiple of a smaller base frequency [9] [10] [12] [17]. | ||
HEAT SHUNTA device (preferably a clip-on type) used to absorb heat and protect heat-sensitive components during soldering [4]. | ||
HEATERSame as a FILAMENT [6]. | ||
HEIGHT-FINDING RADARA radar that provides target altitude, range, and bearing data [18]. | ||
HELIX HOUSEA building at a transmitter site that contains antenna loading, coupling, and tuning circuits [17]. | ||
HENRYThe electromagnetic unit of inductance or mutual inductance. The inductance of a circuit is 1 henry when a current variation of 1 ampere per second induces 1 volt. In electronics, smaller units are used, such as the millihenry (mH), which is one-thousandth of a henry (H), and the microhenry (μH) which is one-millionth of a henry [2]. | ||
HERTZA unit of frequency equal to one cycle per second [2]. | ||
HERTZ ANTENNAA half-wave antenna that is installed some distance above ground and positioned either vertically or horizontally [10]. | ||
HETERODYNE DETECTIONThe use of an a.f. voltage to distinguish between available signals. The incoming cw signal is mixed with locally generated oscillations to give an a.f. output [12]. | ||
HETERODYNING(1) The process of mixing two frequencies across a nonlinear impedance [12]. (2) The process of mixing the incoming signal with the local oscillator frequency. This produces the two fundamentals and the sum and difference frequencies [17]. | ||
HEXADECIMALSame as SEXADECIMAL. A number system with a base of sixteen; also pertains to conditions, choices, or selections that have sixteen possible values or states [13]. | ||
HEXADECIMAL SYSTEMPertaining to the number system with a radix of sixteen. It uses the ten digits of the decimal system and the first six letters of the English alphabet [13]. | ||
HIGH FREQUENCYThe band of frequencies from 3 megahertz to 30 megahertz [17]. | ||
HIGH-FREQUENCY COMPENSATIONSee PEAKING COIL [8]. | ||
HIGH-PASS FILTERA filter that passes a majority of the high frequencies on to the next circuit and rejects, or attenuates, the lower frequencies. Also called a LOW-FREQUENCY DISCRIMINATOR [9]. | ||
HITS PER SCANThe number of times an RF beam strikes a target per antenna revolution [18]. | ||
HOLE FLOWIn the valence band, a process of conduction in which electrons move into holes, thereby creating other holes that appear to move toward a negative potential. (The movement of holes is opposite the movement of electrons.) [7] | ||
HORIZONTAL AXISOn a graph, the straight line axis that is plotted from left to right [10]. | ||
HORIZONTAL PATTERNThe part of a radiation pattern that is radiated in all directions along the horizontal plane [10]. | ||
HORIZONTAL PLANEAn imaginary plane that is tangent (or parallel) to the earth's surface at a given location [11] [18]. | ||
HORIZONTAL-DEFLECTION PLATESA pair of parallel electrodes that moves the electron beam from side to side in a CRT [6]. | ||
HORIZONTALLY POLARIZEDWaves radiated with their E field component parallel to the earth's surface [10]. | ||
HORNA funnel-shaped section of waveguide used as a termination device and as a radiating antenna [11]. | ||
HORN ANTENNASee HORN RADIATOR [18]. | ||
HORN RADIATORA tapered, tubular or rectangular microwave antenna that is widest at the open end [18]. | ||
HORSEPOWERThe English unit of power equal to work done at the rate of 550 foot-pounds per second; equal to 746 watts of electrical power [1]. | ||
HORSESHOE MAGNETA permanent magnet or electromagnet bent into the shape of a horseshoe or having a U-shape to bring the two poles near each other [1]. | ||
HOT CARRIERA carrier, which may be either a hole or an electron, that has relatively high energy with respect to the carriers normally found in majority-carrier devices [11]. | ||
HOT-CARRIER DIODEA semiconductor diode in which hot carriers are emitted from a semiconductor layer into the metal base. Also called HOT-ELECTRON DIODE. An example is the Schottky barrier diode [11]. | ||
HOT-WIRE METER MOVEMENTA meter movement that uses the expansion of a heated wire to move the pointer of a meter; measures dc or ac [3]. | ||
HYBRID CIRCUITA circuit where passive components (resistors, capacitors) are deposited onto a substrate made of glass, ceramic, or other insulating material. Then the active components (diodes, transistors) are attached to the substrate and connected to the passive components on the substrate with a very fine wire [7]. | ||
HYBRID ICsTwo or more integrated circuit types, or one or more integrated circuit types and discrete components on a single substrate [14]. | ||
HYBRID JUNCTIONA waveguide junction that combines two or more basic T-junctions [11]. | ||
HYBRID MIXERSee BALANCED MIXER [18]. | ||
HYBRID RINGA hybrid-waveguide junction that combines a series of E-type T-junctions in a ring configuration. When properly terminated, energy is transferred from any one branch into any two of the remaining three branches [11] [18]. | ||
HYDROMETERAn instrument used to measure specific gravity. In batteries hydrometers are used to indicate the state of charge by the specific gravity of the electrolyte [1]. | ||
HYSTERESISThe time lag of the magnetic flux in a magnetic material behind the magnetizing force producing it. Caused by the molecular friction of the molecules trying to align themselves with the magnetic force applied to the material [2]. | ||
HYSTERESIS LOSSThe power loss in an iron-core transformer or other alternating-current device as a result of magnetic hysteresis [2]. | ||