<s>
The	O
non-linear	O
junction	B-Algorithm
detector	I-Algorithm
,	O
or	O
an	O
NLJD	B-Algorithm
,	O
is	O
a	O
device	O
that	O
illuminates	O
a	O
small	O
region	O
of	O
space	O
with	O
high-frequency	O
RF	O
energy	O
.	O
</s>
<s>
Because	O
the	O
basis	O
of	O
almost	O
all	O
semiconductor	O
electronics	O
is	O
the	O
p-n	O
junction	O
,	O
an	O
NLJD	B-Algorithm
is	O
correspondingly	O
capable	O
of	O
detecting	O
almost	O
any	O
unshielded	O
electronic	O
device	O
containing	O
semiconductors	O
,	O
whether	O
the	O
electronics	O
are	O
actively	O
powered	O
or	O
not	O
.	O
</s>
<s>
In	O
its	O
basic	O
form	O
,	O
an	O
NLJD	B-Algorithm
can	O
also	O
detect	O
things	O
that	O
are	O
not	O
themselves	O
electronic	O
in	O
nature	O
,	O
so	O
the	O
use	O
of	O
the	O
device	O
requires	O
a	O
modicum	O
of	O
skill	O
and	O
experience	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
most	O
modern	O
NLJDs	B-Algorithm
examine	O
the	O
ratio	O
between	O
the	O
second	O
and	O
the	O
third	O
harmonic	O
of	O
the	O
illumination	O
frequency	O
.	O
</s>
<s>
The	O
NLJD	B-Algorithm
was	O
invented	O
by	O
Charles	O
Bovill	O
during	O
WWII	O
.	O
</s>
<s>
As	O
a	O
countermeasure	O
against	O
an	O
NLJD	B-Algorithm
,	O
professional	O
covert	O
listening	O
devices	O
(	O
bugs	O
)	O
of	O
the	O
Central	O
Intelligence	O
Agency	O
were	O
equipped	O
from	O
1968	O
onwards	O
with	O
a	O
so-called	O
isolator	O
.	O
</s>
<s>
Any	O
energy	O
injected	O
into	O
the	O
bug	O
by	O
an	O
NLJD	B-Algorithm
will	O
be	O
absorbed	O
by	O
the	O
resistor	O
,	O
resulting	O
in	O
no	O
(	O
or	O
very	O
little	O
)	O
reflected	O
energy	O
.	O
</s>
<s>
A	O
means	O
to	O
hinder	O
isolating	O
a	O
non	O
linear	O
junction	O
is	O
to	O
add	O
inexpensive	O
diodes	O
to	O
places	O
where	O
the	O
NLJD	B-Algorithm
is	O
expected	O
to	O
sweep	O
.	O
</s>
