18WuD2x

alun • bandstop 61
usually providing a 1:1 or 1:4 impedance ratio
and available in several different forms. It is so
called because it has an unbalanced input suitable
for coaxial transmission lines, and a balanced
output suitable for dipole, Yagi, and quad
antennas.
banana jack The female half of a two-part quickconnector
combination. Splicing of a circuit is
completed by inserting a BANANA PLUG into this
jack.
banana plug The male half of a two-part quickconnector
combination, with sides usually composed
of flat springs that ensure contact with the
female BANANA JACK into which it is inserted.
banana jack and plug
band 1. A continuous range of radio or television
communications 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 discrete
radio or television frequency channels
within a specified range (e.g., the standard AM
broadcast band). 3. A range of wavelengths for infrared,
visible, ultraviolet, X-ray, or gamma-ray
energy. 4. A range of energy levels. 5. A colored
stripe on a resistor or capacitor that forms part of
the code that indicates component value and tolerance.
band center 1. In a given radio or television communications
band, the arithmetic mean of the
lowest and highest frequencies. 2. In a given
band, the geometric mean of the longest and
shortest wavelengths.
band-elimination filter See BAND-REJECTION
FILTER.
band gap In any atom, the difference in electron energy
between the conduction and valence bands.
bandpass 1. The frequency limits between which a
BANDPASS FILTER or BANDPASS AMPLIFIER
transmits ac energy with negligible loss. 2. The
ability to allow passage of signals at a given frequency
or band of frequencies while blocking
other signals. Compare BANDSTOP.
bandpass amplifier An amplifier that is tuned to
pass only those frequencies between preset limits.
bandpass coupling A coupling circuit with a flattopped
frequency response so that a band of frequencies,
rather than a single frequency, is
coupled into a succeeding circuit. Also see BAND-
PASS, 1.
bandpass filter Any resonant circuit, or combination
of resonant circuits, designed to discriminate
against all frequencies except a specific frequency
f 0 , or a band of frequencies between two limiting
frequencies f 0 and f 1 . In a parallel inductancecapacitance
(LC) circuit, the device exhibits high
impedance at the desired frequency or frequencies
and a low impedance at unwanted frequencies.
In a series configuration, the filter has a low
impedance at the desired frequency or frequencies
and a high impedance at unwanted frequencies.
Compare BAND-REJECTION FILTER,
HIGH-PASS FILTER, LOW-PASS FILTER.
bandpass flatness The degree to which a bandpass
device’s attenuation-versus-frequency curve is a
straight line with zero slope within the passband.
band pressure level The net acoustic pressure of a
sound source within a specified frequency range
(band).
band-rejection filter Also called a band-stop filter.
Any resonant circuit, or combination of resonant
circuits designed to discriminate against a specific
frequency f 0 , or a band of frequencies between
two limiting frequencies f 0 and f 1 . In a
parallel inductance-capacitance (LC) circuit, the
device exhibits high impedance at the desired frequencies,
and a low impedance at the unwanted
frequency or range of frequencies. In a series configuration,
the filter has a low impedance at the
desired frequencies and a high impedance at the
unwanted frequency or range of frequencies.
Compare BANDPASS FILTER, HIGH-PASS FIL-
TER, LOW-PASS FILTER, NOTCH FILTER.
band selector Any switch or relay that facilitates
switching the frequency of a radio transmitter, receiver,
or transceiver among various bands.
bandset capacitor In some older communications
receivers, a variable capacitor is used to preset
the tuning range in each band to correspond to
graduations on the tuning dial. This capacitor is
a trimmer or padder operated in conjunction with
the main tuning capacitor.
bandspreading In some older communications receivers,
the process of widening the tuning range
within a given frequency band to cover the entire
dial. Otherwise, the band would occupy only a
portion of the dial, and tuning would be difficult.
It is usually accomplished with a BANDSPREAD
TUNING CONTROL whose range is preset via the
main tuning control and/or a BANDSET CAPAC-
ITOR.
bandspread tuning control An analog adjustment
in some older communications receivers that allows
continuous tuning over a desired band of
frequencies. This control is separate from the
main tuning control.
bandstop 1. The frequency limits between which a
BAND-REJECTION FILTER blocks, or greatly
attenuates, ac energy. 2. The ability to suppress
or block signals of a given frequency or band
of frequencies, while allowing signals of other
frequencies to pass with little or no attenuation.
Compare BANDPASS.