Improvements in Apparatus Employed in Wireless Telegraphy.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in Apparatus Employed in Wireless Telegraphy.
We, GUGLIELMO MARCONI, Electrician, and THE WIRELESS TELEGRAPH AND
SIGNAL Co. LD., both of 28, Mark Lane, in the City of London, do hereby declare
the nature of this invention to be as follows:
In the Specification of a former Patent granted to me No. 12039 of 1896 I
described a receiver in which the ends of an imperfect contact in a local circuit
were connected one to earth and the other to an insulated conductor.
According to this invention the conductor is no longer insulated but is con-
nected to earth through the primary of an induction coil whilst the ends of the
imperfect contact are connected to the ends of the secondary one of the connections
passing through a condenser.
The induction coil preferably consists of a few turns of insulated wire. Over
or under this first winding which constitutes the primary is wound a secondary
winding which constitutes the secondary. The induction coil should preferably
be of thin wire. I have obtained satisfactory results with a coil constituted of
100 turns of copper wire .0060 of an inch in diameter insulated with silk as
primary, and 150 turns of similar wire .0048 of an inch in diameter as secondary,
the diameter of the coil being .4 of an inch. It is desirable that the primary
and secondary windings of the coil should be close to each other.
It is desirable that the induction coil should be in tune or symphony with the
electrical oscillation transmitted the most appropriate number of turns and most
appropriate thickness of wire varying with the length of wave of the oscillation
transmitted.
The capacity of the condenser should be varied (in order to obtain best effects)
f the length of wave is varied.
It is desirable that the conductor connected should offer a large surface and
therefore the use of such materials as broad wire netting in lieu of wire is
lesirable.
!
It is also desirable to employ thick conductors or netting or its equivalents at
he transmitting end.
The introduction of the coil in the conductor not only improves the signals but
lso prevents to a great extent any interference due to atmospheric influences.
Any stray interference can be further minimised by substituting a suitable
apacity to the earth.
Dated this 31st day of May 1898.
1000
G. MARCONI.
THE WIRELESS TELEGRAPH AND
SIGNAL COMPANY LIMITED.
G. MARCONI,
H. JAMESON DAVIS,

page_text: Improvements in Apparatus Employed in Wireless Telegrapny.
We, GUGLIELMO MARCONI, Electrician, and THE WIRELESS TELEGRAPII AND
SIGNAL COMPANY LIMITED, both of 28, Mark Lane, 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 Specification of a former Patent granted to Guglielmo Marconi No.
12039 of 1896, a receiver is described in which the ends of an imperfect contact
in a local circuit were connected, one to earth and the other to an insulated
conductor.
According to this invention the conductor is connected to earth or to a suitable
capacity through the primary of an induction coil or transformer whilst the ends
of the imperfect contact are connected to the ends of the secondary, one of the
connections passing through a condenser. The effect of electrical oscillations on
the imperfect contact seems to increase very greatly with their E. M. F. and not
with their quantity. The object of this invention is to increase the E. M. F. of
the received oscillations by transforming up their E. M. F. at the expense of the
quantity. This greatly increases the distance over which, at parity of other
conditions it is possible to transmit and receive messages.
It is found that if the induction coil or transformer is wound with the ordinary
wire used for bobbins or induction coils it fails to work, and its adoption would,
instead of improving, greatly reduce the effectiveness of the apparatus, and when
the induction coil is wound with very thin wire it only then becomes effective
provided it is wound on a nucleus of suitable diameter. The number of turns
of each winding and the number of layers must also be carefully determined.
If the coil is much longer than two centimetres it is found that unless the
secondary is wound in several sections the two windings must be each in one
single layer, but if the coil is less than 1 c/m long it is advantageous that the
primary and secondary windings should be in several layers. It has also been
noticed that it is an advantage if the number of turns is diminished in each layer
as the distance from the primary increases.
The introduction of this induction coil not only improves the signals but also
prevents to a great extent any interference which might be caused by electrica
atmospheric influences.
Figure 1 is a diagram of the arrangement preferred.
Figure 2 shows a modification.
Figures 3 to 10 are diagrams of various forms of induction coil.
In Figure 1, is a long conductor suspended in the air by insulators, and
is a connection to earth or other suitable capacity.
6 is the local battery and is the relay working a signalling or other instru
ment the arrangements being similar to those described in the former specification
c is the primary of the induction coil or transformer whch is inserted between
and and is the secondary.
e is a condenser placed across the sensitive imperfect contact and the secondar
winding of the induction coil or transformer.
ff are choking coils, their object being to prevent the oscillations generate
in the winding d from running into the battery connections at h and i, whic
would weaken the effect of the oscillations on the sensitive imperfect contact j
Figure 2 shows a somewhat similar arrangement which however, does not gi
quite such good results as Figure 1,

page_text: One plate of the condenser consists of 3 plates of copper foil 3.75 × 2.5 cms.
The other consists of two plates of the same dimensions separated by paraffin
paper .015 c.m. in thickness.
When using the above described induction coil or transformer there is usually
employed as the vertical wire at each station a conductor formed of seven strands
of about 1 millimetre diameter copper wire 140 feet long, the top of the conductor
being about 100 feet from the ground.
In some cases in lieu of the above described conductor a galvanised iron netting
about 2 feet broad and 130 feet long, may be employed, the top of the netting
being about 110 feet above the ground.
Figures 3 to 10 are diagrams of various forms of induction coil. P is the
primary and S the secondary. The primary is to distinguish it from the
secondary shown as a thick line although usually the wires of both are of exactly
the same diameter.
The 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 single continuous longitudinal straight line.
A is the
end of the primary which is connected to the aerial conductor a and E is the
end connected to earth or a capacity. J is the end of the secondary which is
directly connected to the sensitive tube or imperfect contact j and C is the end
which is connected to it through the condenser. G is a glass tube on which the
coils are wound.
The wires are insulated by a single covering of silk.
The following table gives particulars of coils which have been successfully
used

page_text: Figure 3 shows the arrangement which generally gives the best results.
It is found desirable to connect direct to the tube (not through the condenser)
the end of the secondary which is furthest away from the nucleus.
The condenser e may be omitted but in that case the results obtained are far
less satisfactory.
A capacity may be substituted for the earth connection or a condenser introduced
into the earth connection.
The special induction coils shown at Figures 3 to 8 form the subject of another
application No. 6982 dated 1st April 1899 and are not claimed per se in this
specification.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
1. Connecting the conductor to earth through the primary of an induction coil
or transformer, and connecting the ends of the imperfect contact to the ends of
the secondary, one of the connections being through a condenser.
2. Connecting the conductor to earth through the primary of an induction coil
or transformer and the ends of the imperfect contact to the ends of the secondary
and also to choking coils the other ends of which are connected to the local
circuit.
3. Connecting the conductor to earth through the primary of an induction coil
or transformer and the ends of the imperfect contact to the ends of the secondary
both the primary and secondary being of wire not exceeding one fortieth of a
centimetre in diameter.
4. Connecting the conductor to earth through the primary of an induction coil
or transformer and the ends of the imperfect contact to the ends of the secondary,
both the primary and secondary being wound in a single layer.
5. In apparatus such as is referred to in the preceding claims, substituting a
capacity for the earth.
6. Apparatus substantially as described and illustrated in Figures 1 and 2 of
the drawings.
7. Induction coils substantially as described and illustrated in Figures 9 and
10 of the drawings.
7141: 9741
1000
G. MARCONI.
Carpmael & Co.,
Agents for the Applicants.