Radio age (Jan-Dec 1926)

56 RADIO AGE for February, 1926 The Magazine -o^tke-Hwwr EFFICIENCY That Meets the Requirements of Eminent Radio Engineers Apex Vernier Dials are more than mere "knobs." In reality they are instruments endowed with an ultra degree of efficiency. Their rich elegance of finish lends a touch of striking attractiveness to any set. Precision of production and of operation makes a good set a better set — providing greater range of selectivity — positiveness of control — and utmost simplicity of tuning in most difficult stations. Ratio 12 to 1. Clockwise and counter clockwise. No back lash. Royal Brass finish 4-inch $1.50 — 3Viinch $1.25. Satin Silver Finish 4-inch $1.75— 3V4-inch $1.50. DeLuxe Gold (24K) Finish 4i n c h $2.50— 3VW n c h $1.85. Your dealer has them. If not, order direct. APEX Rheostat Dials are as essential to successful operation and pleasing appearance as are Apex Vernier Dials. Royal Brass Finish — 60c. Satin Silver Finish — 70c. DeLuxe Gold (24K)— 80c. APEX ELECTRIC MFG. CO. Dept. 211 1410 W. 59th Street CHICAGO EMS Radio's biggest season is here. Get new catalog showing huge stocks of rac parts, sets, kits at lowest rock-bottom prices. Quick service. Wonderful special offer on best sets, tubes, batteries.'' Write for free copy. iff: W.-C Braun Co, 36-50 S. Clinton St, Chicago, U. S. A.~ RADIO RENCH; WW ^-hBdrv* New Wave Propagation Technique (Continued from page 48) We will assume the medium through which the radio waves pass has such characteristics that the velocity of propagation for a vertically polarized wave differs slightly from the velocity of the propagation for a horizontally polarized wave. It is not necessary for the present purpose to try to explain the reason for this difference in velocity. We may assume the reason for it is due to the electrostatic and magnetic effects, to the retarding effect of the velocity of the vertically polarized wave passing close to the earth, or, on the other hand, due to properties of free electrons in the upper atmosphere. Whatever the cause may be, we may assume such a difference of velocity exists and the mechanical model has been constructed so as to reproduce such conditions. The weights on both sides are tied together with rubber bands. Wave motion in the horizontal or vertical planes can thus be studied independently, and these two wave motions may be adjusted for different velocities. A wave started in the vertical plane maintains itself vertically and a wave started horizontally maintains itself horizontally. If, however, a wave is started in a plane 45 degrees between the vertical and the horizontal, it is found the wave motion proceeding therefrom assumes the shape of a cork screw. The straight line oscillation of the first weight is passed along as an eliptical motion which gradually widens into a circle. Then this circle narrowed down again to an elipse and finally a straight line at right angles to the original line of oscillation. This is exactly in accordance with the theory. The point where the wave has shifted its plane of polarization 90 degrees is the point where the faster of the two waves is half a wave length ahead of the slower wave. From this point on the wave proceeds repeating this peculiar cork screw motion. The fact the twisting of the wave is due to different velocities in the two planes of polarization can also be demonstrated by this model. For this purpose the rubber bands are added to the counter weights. The effect of this is to change the velocity of propagation in the vertical plane, whereas, the velocity in the horizontal plane has not been affected because only the vertical motion is transmitted to the counter weights by the suspension yokes. The system can thus be adjusted so the velocities in the horizontal and the vertical planes are exactly equal. After this has been done it is found the tendency to cork screw motion disappears and the wave remains strictly in the plane in which it has been started. Visualize Phenomena "V\7"HILE this mechanical experiment » » does not bring out any new facts that were not known from the classical theory of wave motion, it helps us to visualize the main phenomena in the radio wave propagation which we are trying to explain. The phenomenon of a constantly shifting plane of polarization which we Tell them nmil rearl It. in RnrUn A no Less wiring — Fewer losses Full, clear, rich tone depends on more than on just good apparatus. 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