Evening star., 1934-06-17

uuC W VIC law IiluO Jul Va 8 oAAi
few people do all the work for t
This is probably correct in prin-
ciple. Manufacturers must produce
devices or apparatus which the aver
age person can operate and use with
out the necessity of taking a post
graduate course in some school.
believe that this Is the reason for the
great strides that we in America have
made in such matters as automobiles
and radio.
In the early days of radio it be-
came very apparent that what was
needed was a single dial control and
not the many knobs and adjustments
which were then required. We could
not ask the listeners to become radio
experts in order to obtain the bene-
fits of broadcasting. However. I be-
lieve that we have gone a little too
far in our endeavor to simplify the
installation of radio apparatus With
a little cooperation from the receiv-
ing set owner himself. we can obtain
vast improvements in reception.
Average Installation Wrong.
Radio engineers agree that the
average radio receiving set is improp-
erly installed. 1t is true that you can
get some signals, but it is also true
that so much more can be accom-
phshed if a few fundamentals are
observed, especially when the apara-
tus is first installed in the home.
This has mainly TO do with the an
tenna installation and the lead-in
wire. 1t costs little more to do the
job properly in the first place and the
results will be amply worth while.
Radio sets have been made very
sensitive and in recent years quite
selective in their ability to receive
distant stations. A good radio engi-
neer recognizes the fact that the
fundamental principle involved is to
obtain as high a ration of signal
strength against interference as pos
sible. If the signal strength is suffi-
GENTLY high, it is not necessary to
use as much application AS an ex-
ample, if the wave carrying a pro-
gram can be received with an energy
level of say. millivolts (unit of
measurement of radio field strength
and the interfering energy picked up
by the receiver is only fraction of
a millivolt, then We have sufficient
ratio Of desired to undesired signals
to permit reception without being
greatly disturbed by background
noise, especially during the soft pas
sages or pauses in the program
Obviously. the radio wave has a Ger
tain intensity or level that cannot
he inHrao SaH nn1ncc the fro for
increases It's power. Therefore, with
the signal intensity fixed, it is neces-
sary to reduce the amount of inter
fering energy which the antenna and
receiver will pick up. in order to in
crease the ration of desired to unde-
sired signal This can be accom-
plished by installation of a modern
antenna system
An antenna has induced in it
voltages by electromagnetic waves,
which may be from the broadcasting
station or due to electrical disturb
ances. proportional to the intensity of
these waves. It is a we'll esta ablished
fact that the waves from electrical
disturbances die down very rapidly
with distance. Even a few feet causes
q very rapid decline in the intensity
OF such waves. Therefore, it is de-
sirable that the antenna itself be
placed as high as possible and far
removed from wire circuits which can
cause such disturbances. The higher
the antenna, the more certain it is to
receive its full share of energy from
the desired wave because these waves
will be less obstructed by neighbor-
ing buildings and structures AS the
usual lead-in wire is really a part of
the antenna, we would be multiplying
this isolating feature we Just men
toned because the lead-in wire would
be closely coupled to the wire cir
cults in the building and would pick
up considerable interfering energy.
The engineers have therefore de-
veloped what is known as trans
mission line" which merely conducts
the radio frequency energy from the
antenna to the receiving set, but does
not, In itself. act as an antenna. An
efficient transmission line, therefore,
picks up no energy from neighboring
wire circuits and simply conducts the
radio energy, which is fed to it by the
antenna, TO the receiving set.
Available and Cheap.
Such transmission lines, complete
with antenna, are available in the
better radio shops and are very rea-
sonable in cost. The better types of
Transmission lines are now in the
form of cable which can be very
easily installed and run for consid-
erable distances through buildings to
the receiving set, so that it is not
necessary to place the receiver near
window or other entering points, as
vas the case with the d-fashioned
lead-in wire.
The receiving set manufacturers
have gone long way in reducing
eXtraneous noise due to 'man-made