The Illustrated Dictionary of Electronics - Loscha

450 minor lobe • mixturerelative to the main lobe. Also see MAIN LOBE,SIDE LOBE.minor loop A subordinate path for the circulationof information or control signals in an electronicsystem (e.g., minor feedback loop). Compare MA-JOR LOOP.minute 1. Abbreviation, min. A unit of measure oftime equal to 60 seconds or 1 ⁄60 hour. 2. Also calledminute of arc. Symbol (‘). A unit of arc measureequal to 1 ⁄60 angular degree or 60 seconds. 3. Generalterm meaning “extremely small.”MIR Abbreviation of memory-information register.mirror 1. A device consisting chiefly of a highlypolished or silvered surface that reflects a largepart of the radiation (such as light) striking it.2. Radar-interference material (see CHAFF). 3. Toreflect, as by a mirror.mirror galvanometer A galvanometer in which amirror is moved by the coil. The mirror either reflectsa spot of light along an external scale, or itreflects the scale, which is then read through asmall telescope.mirror-galvanometer oscillograph See ELEC-TROMECHANICAL OSCILLOSCOPE.mirror image 1. An image or curve that is exactlyreversed relative to a straight line or flat plane,compared to a reference image or curve. CompareBILATERAL SYMMETRY. 2. For a quarter-waveMarconi antenna, the extra quarter-wave elementsupplied by the earth. 3. For an antenna at a distanced above a ground plane, an effective antennaat an equal distance d below the groundplane.AntennaImageλ/4λ/4mirror image, 2Groundmirror-reflection echo A false radar echo or set ofechoes, caused by reflection of the radar beamfrom a plane surface prior to its encountering thetarget or targets. The beam can also be reflectedfrom one target to another.mirror-type meter A meter whose movable coilcarries a small mirror (rather than a pointer) thatreflects a beam of light to produce a spot on atranslucent scale.misaligned head In a tape recorder, a record or apickup head that is incorrectly oriented, with respectto the passing tape.misfire Failure of a gas tube or mercury-arc tubeto ignite at the correct instant.misleading precision In electronic calculationsand data recording, greater precision than the instrumentsor conditions justify. Also see SIGNIF-ICANT FIGURES.mismatch The condition resulting from joining twocircuits, or connecting a line to a circuit, in whichthe impedances are substantially different.mismatched impedances Impedances that areunequal, and thus do not satisfy the conditionsfor maximum power transfer.mismatch factor For a load not perfectly matchedto a driving circuit, the ratio of current flowing inthe load to the current that would flow in the loadif its impedance were perfectly matched to theoutput impedance of the driving circuit.mismatch loss For a load that is mismatched to asource, the ratio P 1 /P 2 , where P 1 is the power amatched load would absorb from the source, andP 2 is the power actually absorbed by the mismatchedload.mistor A variable-resistance device, used to detectthe presence of a magnetic field and to measuremagnetic-field strength.MIT Abbreviation of MASTER INSTRUCTION TAPE.mix 1. To produce a beat signal (either the sum orthe difference frequency) from two input signals.2. The proportion of powdered iron and other inertsubstances in a ferromagnetic transformercore. Different mixes result in different operatingcharacteristics.mixdown A method of combining recorded soundfrom two or more audio tracks, and recording theresult onto an audio tape or disc. It is used to createspecial audio effects.mixed-base notation A number system in whichthe base (radix) alternates between two digit positions.Also called mixed radix notation.mixed calculation A mathematical calculation orexpression in which more than one operation isused.mixed modulation Modulation of several kinds coexistingin a system. Thus, a small amount of undesiredfrequency modulation might accompanyamplitude modulation, or vice versa.mixed number A number having integral (whole)and fractional parts (e.g., 3.14159).mixer 1. A device, such as a transistor or semiconductordiode, used to mix two input signals anddeliver an output equal to their difference and/orsum (see MIXING). 2. See AUDIO MIXER. 3. Anydevice that combines two or more signals, yieldingone output signal whose nature is determinedby the characteristics of the circuit.mixer noise Electrical noise that occurs in aMIXER.mixing Combining several signals so that some desiredmixture of the original signals is obtained.Compare MODULATION.mixture 1. A combination of two or more signalsthat retain their characteristics—even when theyinteract to produce beat-frequency products. 2. A