Aerospace and Electronic Systems Magazine March 2017 - 18

Coltano: The Forgotten Story of Marconi's Early Powerful Intercontinental Station

Box 1
Why did Marconi choose the Coltano site?
* Coltano is a flat and scarcely populated area.
* Its wet soil has a high electrical conductivity,
which eases the radiation of ground waves,
especially at VLF.
* It is located near the Tyrrhenian Sea's
shoreline, in a very favorable position for
communications with Italian colonies in Africa
and with the Americas.
* It is located almost halfway from Rome,
Italy's capital, and Milan, Italy's main
industrial city, and it could be easily
connected to both of them via terrestrial
telegraph lines.

Figure 3.

Electrical conductivity of the soil in Tuscany (from [6]).

* Nearby cities, Pisa and Leghorn, have good
connections with the rest of the country.
* Leghorn hosts the IRN's Academy.
* The Coltano area was an estate of the King of
Italy, Vittorio Emanuele III, who enthusiastically
agreed to make it available for Marconi's
project.
* In his youth, Marconi spent some periods
in Leghorn, where, at the age of 14, he took
lessons on electrical science from Prof.
Vincenzo Rosa. Thus, Marconi was quite
familiar with the area between Leghorn and
Pisa.

Box 2
How does the soil conductivity influence the
ground wave coverage of a radio transmitter?
The benefits of the highly conductive soil
on the transmission of radio signals can be
quantified by the "range factor" (ρ) for ground
waves [10], which is graphically illustrated in
Figure 4, where the transmitter (Tx) operates
at frequency f, with power P and antenna
gain G, and the receiver (Rx) has sensitivity
S. First, let us assume that, given f, the set
of parameters (P, G, S) is such that over a
soil with conductivity 1 mS/s (dubbed the
"reference" scenario) the received signal level
is S for a Tx-Rx separation Dref = 10 km (Figure
4a). In the case of propagation over a soil with
generic conductivity σ the received signal level
will be S for a Tx-Rx separation D, also termed
transmitter's "range" (Figure 4b), and the
range factor is defined as ρ = D / Dref . Figure 5a
(from [10]) shows the values of ρ relevant to
Coltano for f =2, 5, 10 MHz, and Figure 5b plots
ρ vs. f.

Figure 4.

Graphical definition of the range factor ρ for ground waves.

BIRTH AND INFANCY OF COLTANO STATION: THE
MARCONI ERA
In 1903, the Italian Parliament approved Marconi's initiative for
the construction of the radiotelegraphic station in Coltano and
passed a bill providing the financial support, which amounted to
800,000 Italian Lira2 [3]. Then, Marconi visited the site a few times
in 1903-1904 to select the most appropriate location for the radio
station. The design included a main building, which was to host
the transmitter together with the relevant control equipment, and a
couple of long horizontal-wire antennas: one for links with North
America and one for East Africa.
2

18

Roughly 3,500,000 Euro in 2016 [7].

IEEE A&E SYSTEMS MAGAZINE

MARCH 2017



Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine March 2017

No label
Aerospace and Electronic Systems Magazine March 2017 - No label
Aerospace and Electronic Systems Magazine March 2017 - Cover2
Aerospace and Electronic Systems Magazine March 2017 - 1
Aerospace and Electronic Systems Magazine March 2017 - 2
Aerospace and Electronic Systems Magazine March 2017 - 3
Aerospace and Electronic Systems Magazine March 2017 - 4
Aerospace and Electronic Systems Magazine March 2017 - 5
Aerospace and Electronic Systems Magazine March 2017 - 6
Aerospace and Electronic Systems Magazine March 2017 - 7
Aerospace and Electronic Systems Magazine March 2017 - 8
Aerospace and Electronic Systems Magazine March 2017 - 9
Aerospace and Electronic Systems Magazine March 2017 - 10
Aerospace and Electronic Systems Magazine March 2017 - 11
Aerospace and Electronic Systems Magazine March 2017 - 12
Aerospace and Electronic Systems Magazine March 2017 - 13
Aerospace and Electronic Systems Magazine March 2017 - 14
Aerospace and Electronic Systems Magazine March 2017 - 15
Aerospace and Electronic Systems Magazine March 2017 - 16
Aerospace and Electronic Systems Magazine March 2017 - 17
Aerospace and Electronic Systems Magazine March 2017 - 18
Aerospace and Electronic Systems Magazine March 2017 - 19
Aerospace and Electronic Systems Magazine March 2017 - 20
Aerospace and Electronic Systems Magazine March 2017 - 21
Aerospace and Electronic Systems Magazine March 2017 - 22
Aerospace and Electronic Systems Magazine March 2017 - 23
Aerospace and Electronic Systems Magazine March 2017 - 24
Aerospace and Electronic Systems Magazine March 2017 - 25
Aerospace and Electronic Systems Magazine March 2017 - 26
Aerospace and Electronic Systems Magazine March 2017 - 27
Aerospace and Electronic Systems Magazine March 2017 - 28
Aerospace and Electronic Systems Magazine March 2017 - 29
Aerospace and Electronic Systems Magazine March 2017 - 30
Aerospace and Electronic Systems Magazine March 2017 - 31
Aerospace and Electronic Systems Magazine March 2017 - 32
Aerospace and Electronic Systems Magazine March 2017 - 33
Aerospace and Electronic Systems Magazine March 2017 - 34
Aerospace and Electronic Systems Magazine March 2017 - 35
Aerospace and Electronic Systems Magazine March 2017 - 36
Aerospace and Electronic Systems Magazine March 2017 - 37
Aerospace and Electronic Systems Magazine March 2017 - 38
Aerospace and Electronic Systems Magazine March 2017 - 39
Aerospace and Electronic Systems Magazine March 2017 - 40
Aerospace and Electronic Systems Magazine March 2017 - 41
Aerospace and Electronic Systems Magazine March 2017 - 42
Aerospace and Electronic Systems Magazine March 2017 - 43
Aerospace and Electronic Systems Magazine March 2017 - 44
Aerospace and Electronic Systems Magazine March 2017 - 45
Aerospace and Electronic Systems Magazine March 2017 - 46
Aerospace and Electronic Systems Magazine March 2017 - 47
Aerospace and Electronic Systems Magazine March 2017 - 48
Aerospace and Electronic Systems Magazine March 2017 - 49
Aerospace and Electronic Systems Magazine March 2017 - 50
Aerospace and Electronic Systems Magazine March 2017 - 51
Aerospace and Electronic Systems Magazine March 2017 - 52
Aerospace and Electronic Systems Magazine March 2017 - 53
Aerospace and Electronic Systems Magazine March 2017 - 54
Aerospace and Electronic Systems Magazine March 2017 - 55
Aerospace and Electronic Systems Magazine March 2017 - 56
Aerospace and Electronic Systems Magazine March 2017 - 57
Aerospace and Electronic Systems Magazine March 2017 - 58
Aerospace and Electronic Systems Magazine March 2017 - 59
Aerospace and Electronic Systems Magazine March 2017 - 60
Aerospace and Electronic Systems Magazine March 2017 - 61
Aerospace and Electronic Systems Magazine March 2017 - 62
Aerospace and Electronic Systems Magazine March 2017 - 63
Aerospace and Electronic Systems Magazine March 2017 - 64
Aerospace and Electronic Systems Magazine March 2017 - Cover3
Aerospace and Electronic Systems Magazine March 2017 - Cover4
http://www.brightcopy.net/allen/aesm/34-2s
http://www.brightcopy.net/allen/aesm/34-2
http://www.brightcopy.net/allen/aesm/34-1
http://www.brightcopy.net/allen/aesm/33-12
http://www.brightcopy.net/allen/aesm/33-11
http://www.brightcopy.net/allen/aesm/33-10
http://www.brightcopy.net/allen/aesm/33-09
http://www.brightcopy.net/allen/aesm/33-8
http://www.brightcopy.net/allen/aesm/33-7
http://www.brightcopy.net/allen/aesm/33-5
http://www.brightcopy.net/allen/aesm/33-4
http://www.brightcopy.net/allen/aesm/33-3
http://www.brightcopy.net/allen/aesm/33-2
http://www.brightcopy.net/allen/aesm/33-1
http://www.brightcopy.net/allen/aesm/32-10
http://www.brightcopy.net/allen/aesm/32-12
http://www.brightcopy.net/allen/aesm/32-9
http://www.brightcopy.net/allen/aesm/32-11
http://www.brightcopy.net/allen/aesm/32-8
http://www.brightcopy.net/allen/aesm/32-7s
http://www.brightcopy.net/allen/aesm/32-7
http://www.brightcopy.net/allen/aesm/32-6
http://www.brightcopy.net/allen/aesm/32-5
http://www.brightcopy.net/allen/aesm/32-4
http://www.brightcopy.net/allen/aesm/32-3
http://www.brightcopy.net/allen/aesm/32-2
http://www.brightcopy.net/allen/aesm/32-1
http://www.brightcopy.net/allen/aesm/31-12
http://www.brightcopy.net/allen/aesm/31-11s
http://www.brightcopy.net/allen/aesm/31-11
http://www.brightcopy.net/allen/aesm/31-10
http://www.brightcopy.net/allen/aesm/31-9
http://www.brightcopy.net/allen/aesm/31-8
http://www.brightcopy.net/allen/aesm/31-7
https://www.nxtbookmedia.com