Evening star., 1922-06-15
BY A. HYATT VERRILL.
Expert ON Radio TECHNOLOGY.

One of the objections to radio tele-
phone set at home, is the aerial.
Buildings interfere, and it is often
very difficult to find suitable spot
or good support. Landlords and
owners object to aerials on their
roofs: il is often impossible to make
a lightning ground and there are
countless other obstacles to over
come. These many objections may be
overcome by using an indoor aerial
a wire run several times around
room near the ceiling; wire
or garret. down an air shaft.
Even an iron bedstead or bedspring
may be used as an aerial and with
a tube set. especially regeneratiVe
set with two or three stages OF ampii-
fication, excellent results may be OBJ
tanned by such makeshifts.
For the best results, however. the
loop aerial is the one to use for IN
door work. With crystal set loop
aerial is next to useless. unless you
are very near broadcasting sta
ton, but with a tube set, and par
ticularly regenerative set which
can be easily amplified a loop is high
" satisfactory. BY using loop, you
can almost entirely eliminate static
and can practically cut out all inter-
ference. This is due very largely to
the fact that loop aerial is strong
ly directional. that is. waves are
picked up by it when turned towards
the direction in which they come,
while, If at an angle to them. they
are scarcely recorded. Although any
tube set may be used with good re-
suits with a loop, yet specially de-
signed set is far better. Furthermore,
such set is simple. for the direc-
tive effect OF the loop causes it to
act as a tuner itself and a set using
merely a variometer or two and vari-
able condenser will give splendid re-
suits. The one shown in the accom-
panying figure is as good as any.
when using this loop you will do
well to employ Myers tubes. These
have greater amplifying power than
most of the others and messages COM
ing in will be almost as loud as with
many other makes of tubes, using enc
stage or amplification.
Many Different Types.
The loop may be made in any one
of the various ways shown, the main
thing being to keep it as light and
yet as rigid as possible and to pro-
vide means for turning or swinging
il in the direction of the station you
desire to hear. If you wish. it may
be suspended from a hook or from the
ceiling or even from gas or electric
light fixture and thus swung about
and tied in the desired position. No
ground is used. the two ends of the
wires being led to binding posts on
one of the arms or the upright. One
of these Is connected to the aerial ter
minal of the set. the other to the
ground connection as shown In the
wiring diagram.
The loop may be anywhere from
five to eight feet from tip to tip Of the
arms, but an eight-foot loop will
give best all-round results.
OF course, as in the case of any
other a.rial, the larger the loop (pro-
vided the same number of turns OF
wire are used). the longer the wave
lengths it will receive. If you de-
sire a portable aerial which may be
quickly and easily taken apart, IT
may be constructed with arms set
into holes in a hub. as shown. or the
gether. For best results. place
narrow strip Of bakelite or hard
rubber at the tip of each arm where
the wire touches. Cut little notches
in the ends of the arms or the strips
to hold the wires IN position and
Is or is copper of phospher bronze
wire. spacing the turns about one
and one-half inches apart. Then, be
fore permanently fastening the wire
or cutting 1T OFF. test the set. If you
cannot tune down from the long
the music from broadcasting stations,
take of one or two turns of wire, or
il you find the waves brought In are
too short. add a few turns. By hav..
ing two or more loops of different
sizes you can arrange to switch your
set to the smaller one when you
wish to get the broadcasting stations
or to the larger one for long waves
with dot and dash messages.
Handy for Travelling.
If you are at all handy with tools
you can arrange a loop aerial set
which may be taken down and set
up again In a few moments. Th"V
are ideal for travelling or t:tk.Es