US 1783025 A
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' 930.1 A. MEISSN4E4R 83,
ANTENNA Filed June 17; 1925 T H 2 I fig. 5
avwwwoz ALEXANDER MEISSNER Patented Nov. 25, 1930 UNITED STATES PATEINTOFFICE ALEXANDER EIsSNER, on BERLIN, GERMANY, Assienon ro oEsn'LLscHArr. run DRAI-ITLOSE TELEGRAPHIE M. B. H. HALLEsonns, BERLI GERMANY, A CORPORA' TION on GERMANY ANTENNA Application filed June 17, 1925, Serial No. 37,82G, and in Germany July 25, 1924.
One object of the invention is the provision of an antenna suitable for transmitting or receiving short wave lengths.
Another object of the invention is the proprovision of an antenna suitable for short wave lengths and having loading devices 1nse-rted therein in symmetrical relationship with the current distribution under short wave operation. j
The invention is illustrated in the accompanying drawing in which Figure 1 shows a three-quarter wave antenna for radiating short waves;
Figure 2 represents a similar antenna inductively loaded;
Figure 3 shows capacitive loading;
Figure 4 indicates a combination of inductive and capacitive loading; and
Figure 5 shows the vertical portion of the conductor leading to a quarter wave antenna a "plurality of half waves in length.
It is well-known that for the purposes of intelligence transmission by means of short electrical waves so-called space-radiation antennaehave been used. These antennae asa rule consist of a rectilinear wire which is excited to oscillate at three-quarter wave length or a Whole multiple of a half wave length plus one quarter wave length. In Fig: 1 such a straight oscillator is shown jointly with the 9 curve showing the current distribution when excited at three quarter wave length. The part of the antenna between points A and B gives the proportion of the space rad1at1on, while the current of part BC contributes more to the production of surface waves. It is a well known fact that operation on short waves is more desirable at certain times of the day than at others, so that there arises the neces sity to work on longer wave lengths durlng certain portions of the day. Now, the present invention provides a simple arrangeirient adapted to change to long wave operation while using the same antenna tower or mast and the same antenna wire. This isaccom plished by the insertion of wave extension means such as coils, larger condensers, as well as' combinationsoi' coils and capacitiveresistances which of courseis well knowninit: self. Now, according to theinvention these extension-means are inserted or. connected ,in
the antenna wireand are positioned'in a symg metrical manner with reference to the current loops of the short working waves. For
instance, in the case of a space-radiation ang tenna which is eXcitedinjthe manner illus trated in Fig. 1, the coil must be inserted in the middle o-f portion AB, as-depicted in Fig. A
2.. Also a condenser: (shown by the broken lines in the figure) could be connected with the antenna coil mentioned in ordeinthat the desired extension may be obtained. Another form of construction according to the invent1on is illustrated in Fig. 3. Accordinggto the latter, at both ends of the section AB enlarged capacity surfaces by the addition of fan like disposed Wires are provided. In the form of construction of Fig. 4, horizontal capacity surfaces are used at A and B. Fig. 5 illustrates the use and application of the idea 'underlylng the invention to the case in which the antenna radiates at a short Wave andin which the longitudinal dimensions of the antenna wire correspond to one quarter wave length. a
The advantage which the invention offers, as can be readily seen from the examples here cited, consists in that one and the same mast or tower is employed for-the antenna working on short waves and longer waves, and in that the antenna wire for short waves is adapted in the simplest possible way to the transmis corresponds to a short wave length to a substantially longer wave length.
In the claims which follow I shall use the term loop to mean a half of an electrical 5 wave. Thus, the threequarter Wave antennae in Figures 1 through 4 contain one and onehalf loops Having described my invention, I claim: 1. The method of changing the wave length of a space radiation antenna, the cur rent distribution of which has an odd number of half loops and includes at least an entire current loop, which comprises the step of loading the antenna symmetrically with respect to the current loop.
2. A space radiation antenna comprising a conductor the current distribution in which contains a whole and a half current loop, and reactance devices located symmetrically with respect to the whole current loop.
3. The combination with an antenna having a current distribution whereby there are a plurality of current nodes, and at one end a current anti-no de, of loading devices located symmetrically with respect to a pair of adjacent current nodes.
4. An antenna structure for use with either short or long waves comprising a grounded linear oscillator the length of which is an odd number of fourths of the short Wave length,
and having for use with the longer Wave loading devices located symmetrically with respect to the current distribution existing during short Wave operation.