Improvements in Apparatus Employed in Wireless Telegraphy.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus Employed in Wireless Telegraphy.
We, GUGLIELMO MARCONI, Electrician, and TIE WIRELESS TELEGRAPH AND
SIGNAL COMPANY, LIMITED, both of 28, Mark Lane, in the City of London, do
hereby declare the nature of this invention to be as follows:-
This invention relates to apparatus such as is described in the Specification
No. 12326 of 1898 and No. 6982 of 1899 in which the aerial conductor is connected
to a capacity through the primary of an induction coil whilst the receiver is
connected to the secondary.
According to this invention the secondary of the induction coil is broken,
preferably in the middle and the two ends are connected to the battery circuit in
some cases through choking coils, the relay or translating device being in series
with the battery. The other or outer ends of the secondary are connected
directly to the detector or coherer.
It is desirable in certain cases to connect a condenser across the inner ends of
the secondary.
Dated this 19th day of December 1899.
Improvements in Apparatus Employed in Wireless Telegraphy.
We, GUGLIELMO MARCONI, Electrician, and MARCONI'S WIRELESS TELEGRAPH
COMPANY, LIMITED, (formerly known as The Wireless Telegraph and Signal
Company, Limited,) both late of 28, Mark Lane, and now of 18, Finch Lane,
Threadneedle Street, in the City of London, do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
In the Specifications of former Patents No. 12326 of 1898 and No. 6982 of 1899

page_text: is described a receiver in which the aerial conductor was connected to a capacity
which might be the earth through the primary of an induction coil whilst the
terminals of a detector of electrical oscillations for instance a coherer or other
imperfect contact were connected to the secondary.
According to this invention this secondary is broken in the middle or wound
in two parts, the inner ends of the wire being connected to the local battery
circuit which usually includes a relay working an ordinary telegraphic receiving
instrument while the outer ends are connected direct to the detector. It is
advantageous also to place a condenser across the inner ends.
Figure 1 is a diagram of the apparatus arranged according to this invention,
and Figures 2. and show coils which have been found to work well.
In Figure 1A is the aerial conductor connected to one end of the primary
of an induction coil of which the other end is connected by E to a capacity
which may conveniently be the earth. is the secondary of the induction coil
wound in two parts, the outer ends being in connection with the terminals of a
detector T while the inner ends are connected to the two plates of a condenser ³.
B is a battery and R a relay connected to the condenser and working an
ordinary telegraphic instrument. c¹² are choking coils whose object is to pre-
vent oscillations generated in the winding from running into the battery
circuit which would weaken the effect of the oscillations on the detector T.
Figures 2 and 3 show instances of coils with which very good results have
been obtained.
These diagrams are greatly enlarged half longitudinal sections, but are not
strictly to scale. In place also of showing the section of each coil or layer of
wire as a longitudinal row of dots or small circles as it would actually appear,
it is for simplicity shown as a continuous longitudinal straight line.
The following are the details of the coil shown in Figure 2.
The primary wound on a core j'6 cm. in diameter consists of 100 turns
of copper wire 037 cm. in diameter insulated with single silk and coated with
paraffin wax; the secondary is of copper wire 019 cm. in diameter insulated
with single silk covering and is wound over the primary commencing in the
middle and in the same sense as the primary. Each half of the secondary is in
layers of the following number of turns: first layer 77, second 49, third 46,
fourth 43, fifth 40, sixth 37, seventh 34, eighth 31, ninth 28, tenth 25, eleventh 22,
twelfth 19, thirteenth 16, fourteenth 13,, fifteenth 10, sixteenth 7, seventeenth 3,
making 500 in all.
The following are the details of the coil shown in Figure 3.
The primary wound on a core 25 cms. in diameter consists of 50 turns of
copper wire '07 cm. in' diameter insulated with single silk covering. The secondary
is of copper wire 005 cm. in diameter insulated by a single silk covering and is
wound over and in the same sense as the primary. Each half of the secondary
consists of 160 turns in a single layer.
These coils give the best results when the length of the aerial conductor at
each station is 150 feet. When using coils in which the secondary winding
consists of one layer only best results have been noticed when the length of the
secondary winding is approximately equal to the length of the aerial conductor
employed at the transmitting station.
Having now particularly described and ascertained the nature of our said in-
vention and in what manner the same is to be performed we declare that what
we claim is:-
1. In a receiver for electrical oscillations, the combination of an induction coil
the secondary of which is wound in two parts, an aerial conductor connected to
one end of the primary, a capacity connected to the other end of the primary,
a detector connected to the outer ends of the secondary, and a local circuit con-
nected to the inner ends of the secondary.

page_text: 2. In apparatus such as is referred to in Claim 1 placing a condenser across
the inner ends of the secondary.
Dated this 12th day of September 1900.
GUGLIELMO MARCONI.
MARCONI'S WIRELESS TELEGRAPH Co., LTD.,
S. FLOOD PAGE,
HENRY S. SANNA,
Directors.
HENRY W. ALLEN,
Secretary.