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Volume 46, Issue 453
Displaying 1-6 of 6 articles from this issue
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S. UDA1926 Volume 46 Issue 453 Pages 335-351
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSIn the first report of experimental studies on the wireless beam of short electric waves of few metres, it has been shown that the electric field due to the oscillator itself used by the author, in which the plate and the grid coils in the oscillation circuit form the radiators, is directive, namely the field intensity being a maximum in the plane of the coils. But in this case the radiation energy from such closed circuit coils is too small to be taken into service. And also it has been stated that if a single vertical rod antenna of nearly half a wave length is employed, the energy of radiation from the oscillator will be much increased, but at the same time the strength of the field will become nearly equal in all directions.
In order to incresse the radiative power still greater in a desired direction and moreover to maintain the directive property of electric field, metallic rods of finite length may be used as reflectors. Further experiments in connection with this line of investigations are made and some of the results are described in this paper.
For the explanation of the behavior of reflector rods used in the beam system of wireless tele raphy, it is convenient to consider simple cases at first in which merely one or two reflector rods are employed and the length of these rode is equal to or slightly longer than half a wave leugth.
A single reflector rod placed a quarter wave behind a radiating antenna is sufficient to cause directive radiation of radio waves. When the distance between the antenna and the rellector is equal to half a wave length, the electric waves will be radiated chiefly in the direction normal to the line joining the antenna and the reflector. Again, if this distance is equal to three times as a quarter wave length, maximum radiation will exist in three directions.
Two reflector rods are now vertically erected at the distance of half a wave, or a quarter wave length from the antenna, one being on the left and the other on the right side of it. In both cases, the wave energy is projected chiefly in the forward and the backward direetions of the antenna, but the former case gives better directivity than the latter.
Of course it is evident that whether each rod will act effectively as a reflector or not, depends not only upon its relative position with the antenna, but also upon its length. Therefore for a complete consideration of the action of reflector rods, their lengths at diferent values must be taken into account, but since this makes the problem so complicate to understand, the author want to write further descriptions of this point in another paper.
In our experiments, 4.4 metres wave length is employed and the lengths of antenna and reflector rods are all equal to half a wave length, i. e. 220 cms. The intensity is measured with a receiving system comprising a crystal detector and a micro ammeter. It has been very carefully ascertained that this crystal system gives the most consistent results throughout the long time of experiments.
The simplest and comparatively effective reflector may be formed as stated below. A reflector rod is placed a quarter wave behind the antenna and two more reflectors, one being on the left and the other on the right side of it, are placed a half wave distant from the antenna. (see Fig.) These three rods form a tri-antennary reflecting system which will hereafter be called a fundamental "Trigonal reflector". Two more reflector rods CC are shown in the figure. These are not as efficient as a reflector as A and B's, but their existence enables closer screening of waves in the backward direction, and when this reflector system is employed in a receiving station, they are specially effective to eliminate external disturbances from behind.
Comhined with these screening rods, the trigonal reflector is now formed of five rods.View full abstractDownload PDF (1034K) -
R. TORIKAI1926 Volume 46 Issue 453 Pages 352-361
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSAbnormal potential gradient which threatens the layer insulation of transformer co ls, can be removed by shunting each section of the coil with graded capacities.* The auther gives mathematical investigations about the mode of the gradation of the capacity and obtained Cs=δC(1/2y2+constant), where y=distance of the point, considered, from the end surface of the bobbin of coil, containing the electrical neutral point, δ=length of the wire of coil per unit length of bobbin, C= capacity of the wire of coil to ground, per unit length.
If we use the shunting capacity given above, no danger takes place in the transformer coil.View full abstractDownload PDF (404K) -
TAKABUMI KUMAZAWA1926 Volume 46 Issue 453 Pages 362-396
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSFour methods are proposed to measure a phase angle with a single triode. These method; were studied experimentally and theoretically.
Ist method: - Two alternating emfs are impressed to anode and grid. If these two emfs are in opposite phase, the anode and emission currents must be min. Thus, by finding min. anode or emission current, one can join any two emfs in opposite phase, with a triode. In this case it may be said that triode is used like a mere potentiometer. Some phase shifting device, with index of the shifted phase angle, is wanted. Thus with this single triode, two emfs with unknown phase angle may be joined in opposite phase to the shifting emf of the device one by one. Thus the unknown phase angle is measured.
This method was investigated experimentally and obtained the following conclusions.
(i) It is preferable to obtain the min. value of anode current, but not of emission current, as the former is found more easily. (Fig. 2, 3 & 4)
(ii) This min. value is the more distinct the higher the anode and grid potentials. (Fig. 2, 3, 4 & 5) But if the grid potential is made too high, its phase will be shifted due to the grid curient.
(iii) Connect one of the terminals of anode emf to the (+) end of the filament and that of grid emf to a sliding pt. on a potentiometer in shunt with the filament battery. The sliding Point is best set at a Point having alittle higher potential than the neutral. (Fig. 6, 7 & 8)
(iv) By this method, the phase angle can be determined nearly or absolutely at no load.
There are no need keep anode, grid and filament voltages constant during the measurements.
This method is independent to the unstabllity of the triode itself.
2nd method: - Two alternating emfs, having a phase difference α are impressed to anode and grid. Keep anode emf and α constant, and decrease the ., grid emf gradually, then the anode current may bass a min. value. It was found experimentally that, when α is constant, the anode emf and grid emf which gives min. anode current, satis'y a linear equation. (Fib. 12-20)
So, if the grid emf that gives the min anode current at a constant anode emf is given, α can be found.
The range of α, for which this method holds good, is determined Studied the effects of connecting the emfs to various points of filament. (Fig. 21, 22 & 23)
3rd method: - Two alternating emfs are impressed to anode and grid. If there is no effect in anode (& emission) current by changing the sign of grid emf, these two emfs must be in quadrature.
So one can join two emfs in quadrature, instead of in opposite phase in the Ist method. Thus any phase angle can be measured as similar as the Ist method.
In this method, some higher grid emf is recomended. (Fig. 33 & 34)
Also studied that, how can be determined whether it is π/2 lead case or π/2 lag case.
4th method: - In the 2nd method we utilized the min value of the anode current. While in this method, the min. value of the emission current is made use of. This latter holds good for the wider range of α than the former. If α be kept constant, the anode emf is proportional to the grid emf, when these emfs give the min. emission current. (Fig. 36, 37 & 38)
The sensibility of this method is considered. (39 & 40) The following shnple relation is found, when the emission current is a min, value: -μEg+Ep cos α=0, where Eg=max. value of grid emf, Ep= _??_ anode emf, μ=amplification constant.
This equation and the min. value of the emission current at α=-π, are discussed.View full abstractDownload PDF (1521K) -
YASUSI WATANABE1926 Volume 46 Issue 453 Pages 397-405
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSThe following relation exist between the input admittance, Yi and the voltage amplification ratio, K of the thermionic amplifier, the circuital arrangement of which is shown in Fig. 1. jωC2K=Yi-(Yi)0
where (Yi)0 is the input admittance for the case of zero plate impedance.
In the paper "On the Input Admittance", published before by the same author, the circle diagram of the input admittance was treated mathematically and also experiments were described in verification.
In this paper, as supplementary to the previous one, the author considers the circle diagram of the voltage amplification ratio for various cases of plate load'ng, and experiments are made at 100, 000 cycle by means of the CR type a. c. potentiometer.View full abstractDownload PDF (382K) -
M. IWATAKE1926 Volume 46 Issue 453 Pages 406-409
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSIntending to measure the time lag of spark between electrodes of various shapes, the author has utilized the same method as was previously used by the same author for measuring the time lag of spark in air or in oil.
It can be infered from the author's present observations that:-
(I) The time lag of spark in air across a needle-plane gap is less for positive needle than for negative needle, when the gap is kept at equal length.
(2) The time lag of spark of a needle-sphere gap in air is shorter, when the needle is positive, and longer, when the sphere is positive, the comparison being made with equal gap lengths.
(3) The lime lag of spark across a needle-plane gap immersed in transformer oil is shorter, when the needle postive, and longer, when the plane positive, the comparison being made again at equal gap lengths.View full abstractDownload PDF (176K) -
[in Japanese]1926 Volume 46 Issue 453 Pages 410-428
Published: 1926
Released on J-STAGE: November 20, 2008
JOURNAL FREE ACCESSDownload PDF (1108K)
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