Torre Chiaruccia
and Marconi's experiments

Torre Chiaruccia was a masonry tower of about 20m height, situated by the sea on the excellent site of Cape Linaro in Santa Marinella (Ref. WWloc: JN52WA). It was built in the XVI° century to get sight of the muslim ships.

Since 1911 it is property of the ITALIAN NAVY. After that they established the Centro Sperimentale Radioelettrico (Experimental Radio-electric Center) supervised by the CNR (Italian National Research Council). They built a 30 MHz short wave broadcasting plant for intercontinental communication. The antenna consisted of a turning base holding wire antennas. Admiral Alberto Bottini was the Director of the Centre.

During his experiments on the micro-waves between the stations of the Vatican Town and Castel Gandolfo, Marconi observed changings of the receiving signal as soon as some objects moved through the beam of the transmitter antenna. Marconi realized the opportunity to use that effect to locate remote moving objects.
This technics was called RADAR and was completely developed at Torre Chiaruccia. They made a wood frame of 10meter height with a platform to put the transmitter, but it was possible to locate objects only in a short range of about some hundreds meters.
The objects where sheep or cars moving on the near Aurelia street. Therefore natives thought that Marconi invented "the ray of the death" to stop the motor of the cars and kill animals.

They made the first micro-wave superheterodyne receiver to replace the Barkhausen receiver, which was less sensitive.

The micro-wave superheterodyne receiver and its parabolic reflector, was installed up on the Michelangelo Fortress of Civitavecchia. Pointing the antennas towards moving objects it was possible to hear the wave reflected by them in a range of about 10km.

After that the receiver and 2 paroabolic antenna were put on the car of Admiral Bottini and moving along the Aurelia street toward Rome it was possible to hear the waves reflected by the object from Santa Marinella to Ladispoli in a range of about 30 km.

To improve the quality of the listening they let make at the Marconi Workshop of Genoa (where they had better materials) a new model of micro-wave superheterodyne receiver, but the result was not good. In fact the first receiver made in Santa Marinella at Torre Chiaruccia was better.

We remember of two people who worked very close to Marconi during those experiments:

During the Marconi's experiments on the 55cm waves there was an interference of a short waves station. It was the station of Daventry in England, that was transmitting with 31m waves. It was supposed they were harmonics of the short waves that could have a frequency of 500 MHz.
As they received the harmonics it could have been received even a 500 MHz signal. During summer the signals were good. Unfortunately because the restrictions of the war time it was not possible to transmit at 60cm from England.

The experiments were carried out until the day of Marconi's death on 20th July 1937 in Rome.

During the World War Second the Centro Radioelettrico was robbed of its fixtures and half destroyed. On 1st February 1944 the tower Chiaruccia was mined and blasted by the nazists.

In 1957 they rebuilt some rooms to study the diffusion of the ionoshperic echos. Nowadays there a radio beacon of the Italian Air Force.

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