GERMANS TRY WOODEN MASTS

Evening Post, Volume CVI, Issue 4, 5 July 1928, Page 23

GERMANS TRY WOODEN MASTS

A departure which is likely to uttract worlcl-wiclo "attrition is the replacing of the steel anteniia to\vefs at the Munich-Steaclelheim station in Germany with'ivooden towers in an endeavour to eliminate the loss of power duo to the absorption of the radio energy by the steel. Owing to tlio short distance between them, says the "Now York Times," this absorption by the metal towers was a very serious one. A further influence to loss of power was tho circumstance that the natural wave length of the towers lay in the neighbourhood of tho station's wave length. Also, the capacity of the steel towers to ground was high. Tho new wooden towers have mot requirements successfully, it is said, and tosts niiido by the Munich Division of the Technical Telegraph Bui-chu of the Government indicate that the useful radiation of tho antenna, which luul hitherto been only about 20 per cent. <Jf 1 lie ten kilowatts assigned to it, had increased to 02 pci" cent. ■■> Tho wooden towers had to be built on tho same foundations upon which the steel towers stood, the height of tho wooden lowers being reduced to 24G feet to iiTlow for tlio greater surface exposed to wind pressure, whereas the old towers had stood about 328 foci liigh. Tho following details with regard to tlio experiment wcro furnished by officials ;it Munich to the American Cummercial Attache at Berlin:— "It is true that the radiation of the Munich sender after having replaced steel masts by wooden masts increased from about 20 per cent, to more than , (50 percent. .This is principally due to ' the fact that the steel masts could be I erected only about ninety meters from each other and had a comparatively large earth capacity. Unfortunately, the resonance of tho bteel masts was in eloao proximity to tho Munich wave, which resulted in an especially large electric loss, "Compared with this, wooden masts havo proved to bo much more advantageous electrically, as tho loss duo to tho deflection is small, although there is no special insulation to ground. Further, electrical reflection was not discernible. On the strength of these observations, other radio senders will be equipped with wooden masts. In general, wo may say that wooden masts will cost about 20 per cent, more than steel masts of the same height, but that tho costs of upkeep and tho lifo are about the same for both kinds." ' ,