On May 14, 1897, five men sat huddled together in a large wooden hut at Lavernock Point near Cardiff on the west coast of Britain. The wind blew and made the eyes water, but the five kept an eye on the receiver. From a small islet off the coast a flag was suddenly hoisted, and shortly afterwards the men could hear the Morse code sign V. The experiment had succeeded. For the first time, Morse code could have been transmitted as far as five kilometers without a wire connecting receivers and transmitters. Mobile telephony, radio and television broadcasts all stem from the Italian Guglielmo Marconi’s (1874-1937) experiment at Lavernock Point.
Marconi’s invention was based on the theory put forward by James Clerk Maxwell (1831-1879). Maxwell’s theory was that electricity and magnetism move in waves. And what’s more – they create each other. If there is a changing electric field, a magnetic field arises and vice versa. According to Maxwell, there was really only one kind of field – an electromagnetic one – and what he was talking about was not electricity and magnetism but electromagnetism.
Maxwell believed that light is also an electromagnetic wave motion and that there must be other waves with both shorter and longer oscillation times than light. Maxwell was absolutely right, and when you talk on your cell phone or listen to music in it, you use exactly the kind of waves he predicted would be detected.
Hertz and megahertz
It was the German Heinrich Hertz (1857-1894) who first succeeded in proving that the waves Maxwell described really existed.
In 1887, Hertz performed a classical experiment. In a corner of his laboratory, he set up an apparatus with two large metal plates. In another corner he placed a device with a steel wire bent into a ring. The ring was broken by two small pieces of metal with an air gap of one-fifth of a millimeter between them.
When Hertz sent alternating current through the first plant, a spark jumped between the metal plates as the current reached its highest strength. Maxwell’s theory predicted that an electromagnetic field would form.
Hertz had calculated that when the current created a magnetic field in the first plant, the magnetic field would create current in the second plant. Quite rightly, Hertz could see sparks jumping between the pieces of metal in the other plant even though no power was connected there.
Hertz had created electromagnetic oscillations and also been able to capture them. He could later show that the waves moved at the speed of light, that they spread in all directions and that they passed through both solids and water.
Hertz was also able to calculate the length of the waves and found that they were much longer than the light waves. Through his experiment, he showed that Maxwell’s mathematical proof worked in reality.
Hertz died only 37 years old. To honor him, the frequency, that is, the number of wavelengths per second, is now counted in hertz. When tuning to a program on your radio, follow a scale graded in megahertz abbreviated MHz. Mega stands for million, and 1 MHz is thus 1 million hertz. In today’s Gothenburg, for example, P1 is transmitted on the frequency 89.3 MHz.
On the wireless path
Many continued to work on the Hertz discovery, among them the Italian Guglielmo Marconi. His father had plenty of money, and the son could devote himself to his experiments without having to worry about earning any. In the family house in Villa Griffone near Bologna, Marconi was given two rooms for his experiments. Throughout the day, the young researcher sat trapped and tried different ways to succeed with his idea: to send messages through the air without wires.
Several other researchers had improved Hertz’s facility. The Russian Popov had invented the predecessor to the antenna. Marconi found that he could make further improvements by grounding one part of the receiver and connecting the other to the antenna.
One night in December 1894, Marconi woke his mother and asked her to hurry to the study. In the room, mother Marconi saw a bell in one corner and a transmitter in another. The son pressed a telegraph key on the transmitter, and the bell began to ring triggered by an electromagnetic impulse even though no wire was running between the devices.
The mother was overjoyed, but the father was harder to convince of the benefits of the experiment.
– There are other ways to ring a bell, was his comment.
The distance between the clock and the transmitter was only four meters, but in the spring of 1895 Marconi sent out his brother Alfonso with a receiver. Alfonso walked about a mile and a half from the house and disappeared behind a small hill.
Marconi remained in Villa Griffone with a transmitter and sent the agreed signs. To his delight, he saw Alfonso come up the hill and perform a dance of joy – the experiment had succeeded.
To understand how the waves that Marconi sent spread, it can be compared to a stone thrown into a pool of water. Waves form around the stone that move away from it. In a similar way, the waves move away from the transmitter.
Experiment in the UK
Marconi now needed more money than his father could raise, but no one in Italy was interested in his ideas. At the age of 21, he came to Britain to do his military service as a naval attaché at the Italian embassy.
Immediately upon arrival, Marconi was arrested on suspicion of being a spy. The mysterious devices in his luggage were, proof enough, considered a zealous customs officer.
Marconi was only released after the British Telegraph Office’s chief engineer Preece had approved him. Preece tried to create a system to keep in touch with the various lightships that lay off the British coast. Marconi had written about his experiments and Preece had promised to help. His first attempt now was to free Marconi from prison. The story became a treat for the British newspapers.
“An Italian has come here with a positive but without a monkey,” wrote a newspaper. Marconi was so upset that he later refused to apply for British citizenship. But the collaboration with Preece continued, and on May 10, 1897, the decisive experiments began.
At Lavernock Point near Cardiff on the Bristol Canal, the first receiver and transmitter were set up. On the island of Flat Holme five kilometers from the coast, the other was mounted.
On the first day, Marconi and Preece, two English experts and the German Adolf Slaby gathered at Lavernock Point. The flag was hoisted on the island to mark the start of the broadcast, and the five men pricked up their ears to try to catch any sign. After two hours, the experiment was stopped without any signals.
The fault was that the antenna was held up by steel ropes, which enclosed it like a cage and obstructed the signals. The antenna had to be extended and made 20 meters longer. But the result was just a few vague signs.
Marconi decided to take the receiver down to the beach in order to further amplify the antenna signal. It so happened that on 14 May 1897 five men sat huddled in a wooden hut due to the strong wind and waited. Suddenly there came – three short and one long – the Morse code for the letter V. Marconi had succeeded.
Broadcast around the world?
Already a week after the first tests, Marconi managed to telegraph over a three times as long distance using antennas carried by dragons.
The device was improved, and soon more and more ships and lighthouses could start installing wireless telegraphs .
Now the question was how far the signals could be transmitted. Would Marconi’s dream of being able to broadcast across the globe come true?
In December 1901, Marconi sat again waiting for signals on a windy coast, but this time in Newfoundland, North America. Now the decisive test would take place. Was it possible to send signals from Europe to the United States?
Because the earth is a globe, the surface is curved. Most, including Marconi himself, therefore expected the signals from Europe to continue straight into space. But when the time came, Marconi heard the agreed morning signal: three short for the letter p. The radio waves had not disappeared into space.
Marconi, however, did not know why the experiment was successful. A couple of physicists proposed the theory that the radio waves bounced off the earth’s air layer and returned to the earth’s surface. It was not until the 1920s that the British physicist Appleton succeeded in proving that the theory was correct. The radio waves can bounce several times against the ionosphere and thus be transported around the entire globe.
When Marconi showed that it was possible to telegraph wirelessly all over the world, he was again hailed by everyone – except the Anglo-American telegraph company, which saw his entire business threatened.
Marconi had to suspend its experiments on Newfoundland, as the company claimed they had the exclusive right to telegraph broadcasts in America. But the development could not be stopped.
Wireless telegraphy gained enormous importance for shipping. Ships in distress at sea could now telegraph for help from other ships in the vicinity.
The radio is making its entrance
When Marconi returned to Italy at the age of 29, he was received as a head of state. The huge crowds gathered to see him forced Marconi’s train to stop outside the city limits.
Marconi still has to solve a number of problems. One of them was to make the receiver receive only the wavelength the transmitter transmits. As the number of devices increased, the problem grew. If you on a radio did not have a certain wavelength for each program, everyone would be heard at the same time.
Marconi solved that problem. When it had succeeded in transmitting telegrams without wires, researchers soon became interested in the possibility of also transmitting speeches and music – what we today call radio. After the end of the First World War in 1918, Marconi worked on the development of radio . Already during the war he had managed to make telephone contact with a warship at a distance of five miles.
When Marconi died in 1937, he received a state funeral. His grave and his home became memorials. But Marconi was honored already in his lifetime; In 1909 he was awarded the Nobel Prize in Physics.