LDG Z-100Plus Operation Manual page 13

circuit. A At any given
of capaci itive or induc ctive "reacta
Transmitt ters, transmis sion lines, an
The output circu uits of a tr
character ristic impeda ance. For rea
is nomin nally 50 ohm ms resistive,
three par rts of the sy ystem have
maximum m transfer o of power fro
output c ircuit and t transmission
presents 50-ohm, non n-reactive lo
will exhi bit capacitiv ve or inductiv
When n the imped ance of the
line, a "m mismatch" i is said to ex
reflected from the a antenna bac
reflected energy is st trong enough
The r ratio of tran nsmitted to r
SWR of 1 (sometime es written 1:
increases s to 2, 3, or h higher. As a
SWR of 2 or less. Tu ube exciters
resonant at the opera ating frequen
the case; ; operators
reactive a antenna and
F = = Forward p
R = Reflected
SW WR is meas
a d device called
bridge", inserted in
between the transm mitter and th
This circ uit measures s forward an
power fro om which S WR may be
(some m meters calcu ulate SWR
More adv vanced units s can measu
and refle ected power r simultane
show the ese values a and SWR at
time.
An a antenna tune er is a devi
cancel ou ut the effects s of antenna
Tuners add capaci itance to c
inductive e reactance i n the antenn
versa. Sim mple tuners
and indu ctors; the op perator adjus
hand wh hile observin ng reflected
the SWR R meter until l a minimum
RF frequenc cy, each of t
ance".
ntennas, and i
ransmitter,
asons beyon
, with zero
the same i
om the tran
n line are o
oad only at it
ve reactance
antenna is d
xist. In this
ck down the
h, it can dam
reflected ene
1) indicates
a general rule
are somewh
ncy, it will s
often need to transmit
a higher SW WR.
power
d power
ured using
d an "SWR
the transm mission line
he antenna.
nd reflected
e calculated
for you).
ure forward
ously, and
t the same
ce used to
a reactance.
cancel out
na, and vice
use variable e capacitors
sts them by
power on
m SWR is rea
these can exh hibit resistan
impedance
the transmi ssion line,
nd the scope of this docu
capacitive a and zero ind
mpedance, the system
nsmitter to t the antenna
of fixed, car refully desi
ts natural res sonant frequ
e, causing it t to have an im
different from m that of th
case, some of the RF e
e transmissi ion line and
mage the tran nsmitter's ou
ergy is calle d the "stand
a perfect ma atch. As mor
e, modern so olid state tra
hat more tole erant of high
show an SW WR close to
t at frequen cies other t
ached. The L LDG Electro
nce, and imp pedance in th
and the an ntenna, all h
ument, the s tandard imp
ductive com mponents. W
is said to b be "matched
occurs. Wh hile the tran
gned imped dance, the a
uencies. At o other frequen
mpedance ot ther than 50
he transmitte er and transm
energy from m the transm
d into the t transmitter.
utput circuits s.
ding wave ra atio", or SW
re energy is r reflected, th
ansmitters mu ust operate w
h SWR. If a 50 ohm ant
1. However, , this is usua
than resonan nce, resultin
onics Z-100P Plus automa
PAG
he form
have a
pedance
hen all
d", and
nsmitter
antenna
ncies, it
ohms.
mission
mitter is
If this
WR. An
e SWR
with an
tenna is
ally not
ng in a
ates this
GE 13