Projected and reflected from metallic objects, the basic principles which later led to a host of radio sciences were briefly examined. These primitive UHF and microwave apparatus formed the basis of modern communications systems. Some experimenters discovered that these energies could produce heating effects at a distance. Others retrieved usable electrical energy by rectifying these otherwise high frequency alternating wave beams. Experimenters began investigating the possibility that these extremely high frequency radiowaves might provide better transmission properties with low power application. It was anticipated that increased frequency would yield increased communications “reach”. These researches began with transmitters which could beam vocal signals across a meadow. They were, in fact, barely improved versions of those used by Augusto Righi and Oliver Lodge. In time, a new application of vacuum tubes began developing and extending the available radio range to unheard frequencies. “Superhigh” radiowave frequencies, though invisible, had concentrated power approaching that of arc fight beacons.
The decade between 1920 and 1930 proved to be a most remarkable demonstration of the inventive resource represented by an international consortium of radio experimenters. New super high frequency generators appeared everywhere, patents abounding. Vacuum tubes of a great variety began coming into vogue, as amateur experimenters investigated the mysteries of SHF radiowave transmission. Invented by a great population of enthused amateur experimenters, the flood of superhigh frequency vacuum tube generators represented a trend which, in the minds of those who so invented, desperately hoped to imitate Tesla and his distinctive systems. Inadvertently, a few young inventors actually did succeed in rediscovering somewhat of his technology; but these were weak and undeveloped embodiments of systems which Tesla himself had already greatly surpassed. The inventors who brought their Tesla-like systems forward were not disfavored, but were not encouraged to pursue their revolutionary trends. Therefore, these inventions came as “one hit wonders”, there usually being nothing more from the names which so fervently produced them. Nevertheless, there are those few patents which represent this accidental replication of Teslian findings in impulse technology. Impulse transmitters of Roberto de Mouro, Bela Gati, Frederick S. McCullough, Conrad Reno, and others are true wonders; representatives of that phenomena in which repressed discoveries continually reemerge.
SUPERHIGH FREQUENCY WAVES
The first major development of Super High Frequency tubes came with the needs of World War II England. The heavy bombing raids on English soil, the early attempt by the Luftwaffe of Adolf Hitler to crush that nation, was resisted through an initially meagre scientific resource. Only the indomitable fortitude of brave souls fighting impossible odds proved the turning of a tide, in both revolutionary science and in the eradication of tyranny. The two seemed closely associated in that the rise of science spelled defeat for fascism. The only available technology for the “early warning” of Nazi air raids were acoustic listening systems, technology adapted from the scientific amusement pages of Victorian Epoch periodicals. Though developed into a wonderful state of perfection, these large multiple concave cup systems mounted on swivels, could not provide the fast warning capabilities so desperately sought The only other tools for early warning were the and fog penetrating arclamps, yet another science which had been perfected before the prior Century’s turn. The challenge stood before those whose tasks were now doubled, fighting the foe while simultaneously producing new technology.
Those who at last had begun enjoying peace were not concerned with the oudandish threat of a Second World War. Nevertheless as guided missiles became the vengeful expressions of lunacy, the absolute need for readiness, for new technology to defeat and utterly obliterate the Nazi foe, commenced. An enemy unseen is a frightful prospect to defeat An enemy seen is not threatening. Soaring at supersonic speeds across the English Channel, V-l “buzz bombs”, and later V-2 missiles, required an alert ready system. Having an ability to reach targets miles out over the sea, long before they reached the coast. A new radiobeam technology was desperately sought Those who recalled the UHF “radio searchlight” of Christian Hulsmeyer attempted duplication and adaptation of the same for their more contemporary and immediate needs. Science again was coming to the needs of an assailed people.
By August 1938, North Sea and Channel coastlines were watched by a chain of “metric” (UHF) radar stations. After observing the initial experimental results and military effectiveness of the first simple “longwave” RADAR systems, engineers were encouraged to pursue their objectives with neither delay nor diminished effort What began with UHF beams soon shifted the emphasis toward the development of a SHF beam system for long distance ranging and detection. The essential problem facing these engineers was that of power. The effectiveness of the system depended upon the intensity of reflected energies. The extensive sea-searching beams now required both higher resolution as well as extremely high power.
SHF beams were relatively more “optical” than the UHF metric waves, being required precisely because of their high resolving properties. Bounced from metal surfaces, these echoes contained inherent detail which could be discriminated by appropriate scanning detectors, at first a simple oscilloscope. The engineering problems demanded the generation of these super high frequencies. Additionally, these SHF signals had to be enormous in strength. The extensive sea-searching beacons, required by a coastal watch along both the North Sea and the Channel, demanded power levels of a megawatt per system. But those UHF and SHF vacuum tubes of the 1920’s, considered novelties of the electronic tube trade, were not made to produce powerful signals at these frequency levels. Electron currents had to release enormous amounts of SHF energies, and supply this amount of power in a continuous reserve. The operation characteristics of any potential RADAR power source were already theoretically severe.
Superhigh frequency vacuum tubes of this era may be classified into three succinct categories. Notable in this first expansion of frequencies upward were the early “lighthouse” and “acorn” tubes, which attempted the generation of SHF across the smallest possible vacuum gaps. These simple and straightforward designs, named for their actual appearance, were analogues of triodes. These tiny embodiments sought the achievement of UHF and SHF energies in an analogous manner as triodes, which used resonant circuits to build up powerful self-regenerating alternations. The chief importance of these early tubes was that they permitted the study of UHF and SHF energies, radio frequencies so very high that they could only be measured in terms of wavelength! The problem with SHF alternations was their small resonant product values. There were geometric reasons why certain radio frequencies became the most powerful expressions of the art, reasons which successfully produced the most powerful communication embodiments. These tubes could employ neither the large capacitor surfaces nor inductors which, in triodes, produced the most powerful high frequency alternations.
- CHAPTER 4
- CHAPTER 6