The Challis messenger. (Challis, Idaho) 1912-current, 1922-11-15

Is often used as cOunterpOiSe and
connection is made with 1t by means
Of number of copper plates or an
interconnected network Of wires, sunk
into the ground at various places with
In the area underneath the antenna.
These buried conductors should have
a low resistance and should be put
deep enough so that the earth around
them is permanently moist See Fig
ure Is for counterpoise of this type.
The Beverage antenna Is one of the
most recent additions to the art of
short.wave radio reception. Due to its
characteristics, it was used at Ar
drossan, Scotland, last December,
when % amateurs succeeded In bridg-
ing the Atlantic with radio.
The Beverage antenna is adapted to
the reception Of signals on single
predetermined wave length. 1t con-
sists of one wire supported on 10 to
12-foot posts, this wire having a
length Of either one or two even wave
lengths. If designed for 2OO-meter
reception, the wire will be either $500
or 1900 feet long.
Unlike the customary form Of an
tenna, this wire Is grounded at both
ends. At the far end, away from the
receiver, 1t Is grounded through nom
inductive resistance Of from $50 to 400
ohms, and at the receiving end through
a variable inductance. In the case OF
the receiver used at Ardrossan, five
stages of radio frequency amplifica-
ton, a regenerative detector and two
stages Of audio frequency amplifca-
ton were used.
As stated above, the Beverage an
tenna Is designed for reception OF
single wave length, depending on the
length Of the antenna wire. II other
wave lengths are to be received, the
length of the wire must be changed.
II has been found that the signal
strength using 400 feet of wire, II
feet above the ground. is approximate
ly the same as would be heard with
single vertical antenna wire, 100 feet
In height. However, the Beverage an
tenna is highly directional, and on ac-
count of this fact, interference from
directions other than those from which
one wishes to receive is reduced to
minimum. Also, due to the short dis
lance from the ground, static and at
mospheric disturbances are almost
eliminated.
In general, 1t may be said that the
Beverage antenna Is extremely well
adapted for the long distance recep-
ton of signals from given station
whose transmitting wave length is
known.
Often by erecting an elaborate an
tenna system, the amateur does not
get as coed results as would be OBJ
tanned from a simple, well-located one.
The function of an antenna Is to cut
the electromagnetic and relectro-static
components of the field radiated by
the transmitter, and have induced in
II an electro motive force which will
cause a current to flow in the antenna
circuit.
The capacity and inductance Of the
receiving antenna plus small amount
Of Jumped inductance In the station to
furnish drop to operate the receiv-
Ing set directly or magnetic Reld to
transfer energy to a second oseillat-
ing circuit, should be equal to the nat
ural period of the received wave.
ROughl1, the natural period OF single
wire aa.enna Is 1.22 times the length
| e the antenna proper. plus the lead
! In. This natural Of the antenAa sys
tenn should be, as stated above. Just
slightly less than the wave length or
which reception u Desired. by sctua