The Illustrated Dictionary of Electronics - Loscha

alun • bandstop 61usually providing a 1:1 or 1:4 impedance ratioand available in several different forms. It is socalled because it has an unbalanced input suitablefor coaxial transmission lines, and a balancedoutput suitable for dipole, Yagi, and quadantennas.banana jack The female half of a two-part quickconnectorcombination. Splicing of a circuit iscompleted by inserting a BANANA PLUG into thisjack.banana plug The male half of a two-part quickconnectorcombination, with sides usually composedof flat springs that ensure contact with thefemale BANANA JACK into which it is inserted.banana jack and plugband 1. A continuous range of radio or televisioncommunications frequencies or wavelengths,usually designated by the lowest and highest frequencies,or the approximate wavelength (e.g.,the 20-meter amateur radio band). 2. A set of discreteradio or television frequency channelswithin a specified range (e.g., the standard AMbroadcast band). 3. A range of wavelengths for infrared,visible, ultraviolet, X-ray, or gamma-rayenergy. 4. A range of energy levels. 5. A coloredstripe on a resistor or capacitor that forms part ofthe code that indicates component value and tolerance.band center 1. In a given radio or television communicationsband, the arithmetic mean of thelowest and highest frequencies. 2. In a givenband, the geometric mean of the longest andshortest wavelengths.band-elimination filter See BAND-REJECTIONFILTER.band gap In any atom, the difference in electron energybetween the conduction and valence bands.bandpass 1. The frequency limits between which aBANDPASS FILTER or BANDPASS AMPLIFIERtransmits ac energy with negligible loss. 2. Theability to allow passage of signals at a given frequencyor band of frequencies while blockingother signals. Compare BANDSTOP.bandpass amplifier An amplifier that is tuned topass only those frequencies between preset limits.bandpass coupling A coupling circuit with a flattoppedfrequency response so that a band of frequencies,rather than a single frequency, iscoupled into a succeeding circuit. Also see BAND-PASS, 1.bandpass filter Any resonant circuit, or combinationof resonant circuits, designed to discriminateagainst all frequencies except a specific frequencyf 0 , or a band of frequencies between two limitingfrequencies f 0 and f 1 . In a parallel inductancecapacitance(LC) circuit, the device exhibits highimpedance at the desired frequency or frequenciesand a low impedance at unwanted frequencies.In a series configuration, the filter has a lowimpedance at the desired frequency or frequenciesand a high impedance at unwanted frequencies.Compare BAND-REJECTION FILTER,HIGH-PASS FILTER, LOW-PASS FILTER.bandpass flatness The degree to which a bandpassdevice’s attenuation-versus-frequency curve is astraight line with zero slope within the passband.band pressure level The net acoustic pressure of asound source within a specified frequency range(band).band-rejection filter Also called a band-stop filter.Any resonant circuit, or combination of resonantcircuits designed to discriminate against a specificfrequency f 0 , or a band of frequencies betweentwo limiting frequencies f 0 and f 1 . In aparallel inductance-capacitance (LC) circuit, thedevice exhibits high impedance at the desired frequencies,and a low impedance at the unwantedfrequency or range of frequencies. In a series configuration,the filter has a low impedance at thedesired frequencies and a high impedance at theunwanted frequency or range of frequencies.Compare BANDPASS FILTER, HIGH-PASS FIL-TER, LOW-PASS FILTER, NOTCH FILTER.band selector Any switch or relay that facilitatesswitching the frequency of a radio transmitter, receiver,or transceiver among various bands.bandset capacitor In some older communicationsreceivers, a variable capacitor is used to presetthe tuning range in each band to correspond tograduations on the tuning dial. This capacitor isa trimmer or padder operated in conjunction withthe main tuning capacitor.bandspreading In some older communications receivers,the process of widening the tuning rangewithin a given frequency band to cover the entiredial. Otherwise, the band would occupy only aportion of the dial, and tuning would be difficult.It is usually accomplished with a BANDSPREADTUNING CONTROL whose range is preset via themain tuning control and/or a BANDSET CAPAC-ITOR.bandspread tuning control An analog adjustmentin some older communications receivers that allowscontinuous tuning over a desired band offrequencies. This control is separate from themain tuning control.bandstop 1. The frequency limits between which aBAND-REJECTION FILTER blocks, or greatlyattenuates, ac energy. 2. The ability to suppressor block signals of a given frequency or bandof frequencies, while allowing signals of otherfrequencies to pass with little or no attenuation.Compare BANDPASS.