Among about six measurements, made on successive days, not one value showed a difference of more than robo of the average value.

Other emissions from that station will be made according to a definite program, when the preliminary trials, in order to determine the best times of the day and the most appropriate wave-length, will be concluded.

Another work of an international nature has been the preparation of reports sent to the British National Committee to be submitted to the international conferences of the U. R. S. I. In 1922, the first international meeting took place at Brussels, when the U. R. S. I. was created and a report was issued stating the present condition of standards and measurements in Great Britain at the time.

The following conference took place at Washington in 1927, on which occasion an additional report was submitted, together with proposals for future work. On the occasion of the most recent conference, in 1928, held again at Brussels, another report was again issued on the international work accomplished and on the general condition of frequency and measurement standards in Great Britain.

Several definite proposals were submitted and discussed at this meeting and the author, as chairman of the Committee on Standards and Measurements, assumed the responsibility of organizing a national and international work according to the following plan:

1. Putting into circulation of piezo-electric oscillators for the purpose of making international comparisons.

2. Simultaneous measurements of the short-wave quartz stabilized station of Arlington.

3. Emission from a British radio-broadcasting station of a musical frequency modulation produced by a tuning-fork, operating very regularly and measured with great accuracy.

This last emission will probably be amplified to insure the possibility of making simultaneous measurements in France, Belgium and England, of the carrier wave frequency of the same or of another radio-broadcasting station controlled by a tuning-fork.

The U. R. S. I. also proposed the preparation of brief descriptions of modern measurement methods for various fundamental radio units used by the national authorities of the various countries which are members of the Union.

34

STATEMENT OF N. T. M. (RADIO-HOLLAND) CONCERNING TOPIC 4 OF THE PROGRAM 1

1

NORMAL RADIATION POWER OF TRANSMITTERS WITH SHORTER WAVES THAN THE FUNDAMENTAL WAVE OF THE ANTENNA

According to Article 13 of the Regulations of the Treaty of Washington, 1929, Paragraphs 4e, 5c, 6e and 9e, the following must be mentioned as one of the characteristic data:

Normal radiated power expressed in meter-amperes or, lacking this, the height of the antenna and intensity of the current at the base of the antenna.

[Enclosed with Circular Letter No. R 30/113, dated August 17, 1929, of the International Bureau of the Telegraph Union, Radiotelegraph Service.— H. F. W.]

In the first place, we would like to state that it seems that we have generally misinterpreted the meaning of the expression pouvoir de rayonnement used in the French text, for, in our opinion, the pouvoir de rayonnement is the "aptitude", the "ability", of the antenna to radiate, and not the power of radiation, as we have been able to notice in several translations. The puissance [pouvoir?] de rayonnement can not be expressed in meter-amperes.

As known, the extent of the electric and magnetic field, and with that the tension induced in the receiving antenna, is at a point distant from the transmitter directly proportional, depending on the product of the effective height of the antenna and the current measured at the center of the current.

As the number of meter-amperes therefore is a direct measure for the quality of the transmitting installation, it is not an expression for the power of radiation.

In order to avoid errors in the expression used in the original French text pouvoir de rayonnement, it seems recommendable to submit this question to the next C. C. I. Conference.

On this occasion it will distinctly be shown how the expression "meter-amperes was formed, from which it is easily shown why it gives difficulties for short waves.

The formula which led to the expression " meter-amperes " will, in general, have a value only when the transmitting antenna operates on a wave-length λ, greater than or equal to fundamental wave d。;

1.

When the wave-length is smaller than the fundamental wave, as is often the case in these last years by sending waves of very short length, the way in which the various factors of the transmitting antenna appear in the formula indicating the extent of the electric field, is much less simple.1

It is easy to see that, when one considers that it is immaterial for the first class of waves whether a high antenna and a small current intensity or a low antenna and a high current intensity is used, so long as the products of both are the same. For the second class of waves, this is not the case. In addition, in view of the fact that the electric field depends on many other elements besides wave-lengths of the last-mentioned category, it would be useless to deduce an expression of the corresponding formula for wave-lengths of this category which could be used as a judgment of the quality of the transmitting antenna. That is why it seems to us

'We would like to refer to publications by Dr. B. van der Pol in the Proceedings of the Physical Society of London (1917) and Jahrbuch für drahtlose Telegrafie (1917); and those of Stuart Ballentine in Proceedings Institute Radio Engineers (December 1924), and many other later ones.

recommendable to mention the quantities of the transmitting antenna by which an idea may be given on the manner according to which the antenna is radiating. If our interpretation of the expression pouvoir de rayonnement given above is correct, it expresses as well as possible what is required by Article 13, Paragraph 4e, etc.

For a single vertical antenna, connected with the earth at the extreme lower end, it would be sufficient, considering that the wavelength is already mentioned under Paragraph 4d, etc., to mention the total length of the antenna and the current, measured at the center of intensity.

This data could easily be mentioned in columns 6 and 7 of the Nomenclature, but then the difficulty arises that in practice, it is not always easy to determine the intensity measured at the center of intensity. Much more data would be required from a transmitting antenna of a more complicated type, for example, a directed antenna with reflector.

That is the reason why we believe Article 13, Paragraphs 4e, 5c, 6e and 9e, can be interpreted as follows:

In case the antenna is excited by a vibration, the frequency of which is smaller than the fundamental frequency of the antenna, the number of meter-amperes or, lacking this, the height of the antenna and the intensity of the current at the base, will be indicated.

If the antenna is excited by a vibration the frequency of which is greater than the fundamental frequency of the antenna, the power transmitted at the high-frequency generator, or, if this power is followed by one or several amplification stages, the power transmitted at the last stage, preferably with the following, will be indicated:

1. The length of the effective part of the antenna wire by expressing in wave-lengths under the formula:

a+b+c+--
2

in which figures a, b, etc., represent the number of half-lengths of current distribution wave, measured successively along the wire in such a way that a new number is used on each point where the phase changes;

2. The number of wires n;

3. The height h, of the lower point above the ground (expressed in wave lengths);

4. The direction D when the antenna has a directive effect to be represented by the angle, made with the true North at the place of the station:

(a) If the antenna has no reflector, by

D=a and a+ 180°;

(b) If the antenna has a reflector, by—

D= a;

(c) If the antenna has a reflector, but with the possibility of radiating in one of the two directions, by—

D=a or a+180°;

5. The width b of the directed antenna, to be expressed in wavelengths;

6. The angle 6, made by the wires in relation to the horizon; 7. The shape of the wire, if it is not a single straight wire, for example, a T-shaped antenna and an L-shaped antenna;

8. The height h2 of the horizontal part above the ground, to be expressed in wave-lengths.

We believe that in such a way, by a summary indication, an idea may be given of the antenna as is shown in the following example. I. 12 kw; D=160° or 160° + 180°; n=24; l=(†); b=114; h1=1; 0=90°.

This will therefore represent an installation of a power of 12 kw transmitted at the last stage and with a directed antenna, which can

FIGURE 1

FIGURE 2

FIGURE 3

transmit at will, either in the direction 160° or in the direction 160°-180° and the effective wires of which, 24 in number, have a length of one wave-length and a half with a current distribution as shown in Fig. 1. The width of the directed antenna is eleven wavelengths and a half, the height of the lower part of the wire above the ground is one-half wave-length, while the wires are suspended vertically.

II. 1 kw; n=1; 7= (2); 0=0; h1 = 4.

This is an installation of a power of 1 kw transmitted at the last stage with a one-wire horizontal antenna situated at one-half wave-length above the ground, of one wave-length with a current distribution, as shown in Fig. 2.

This is an installation of a power of 1 kw transmitted at the last stage with a one-wire vertical antenna of a length of threefourths wave-length, connected with the ground at the lower end, with a current distribution, as shown in Fig. 3.

Finally, we think it desirable to recommend to submit to the next conference at Madrid, the question as to in what manner the unification of Paragraphs 4e, 5c, 6e and 9e of the Regulations might be applicable, in a uniform manner, for all wave-lengths.

35

LETTER OF THE MOROCCAN GENERAL INSPECTOR, DIRECTOR OF THE OFFICE OF POSTS, TELEGRAPHS AND TELEPHONES, TO THE NETHERLAND DIRECTOR GENERAL OF POSTS AND TELEGRAPHS, JULY 18, 19291

STUDY OF THE INTEGRATION OF NORTH AFRICAN BROADCASTING STATIONS IN THE Wave-length ALLOCATION PLAN ESTABLISHED BY THE PRAGUE CONFERENCE

The Prague Conference refused to integrate in its wave-length allocation plan the North African broadcasting stations (Algeria, Morocco, Tunis).

The consequence is, particularly for Morocco, that Radio-Morocco, whose wave-length, originally fixed at 416 meters by the International Broadcasting Union and now at 414 meters, is liable to interfere with Dublin (413 meters) and Berlin (418 meters).

In the general interest of broadcasting, it is important that the decisions of the Prague Conference regarding North African stations be revised.

Consequently, I have the honor to beg you kindly to consider the possibility of adding the following question to the program of the meeting at The Hague:

Study of the integration of North African radio broadcasting stations in the wave-length allocation plan established by the Prague Conference. Please accept [etc.]

1

DUBEAUCLARD

General Inspector, Director of the Office of

Posts, Telegraphs and Telephones of Morocco

' [Enclosed with Circular Letter No. R 30/123, dated August 22, 1929, of the International Bureau of the Telegraph Union, Radiotelegraph Service, which also gives the following useful information.

Since the application of the Brussels and Prague plans establishing the separation régime of 9 kc/s, the conversion tables now at disposal are insufficient. In order to remedy this state of affairs, Mr. Em. Delvoie, Director of the Technical Institute at Tongres (Limbourg-Belgium), will publish at the beginning of September, a table of 10,000 ratios of 7 decimals. It will be possible, with this table, to determine at once more than 80,000 reciprocal ratios. This work, containing about sixty pages, will contain an introduction giving the necessary explanations (in several languages) on its use and advantages.-H. F. W.]