Topband: Fence "ground screen" instead of wire radials?

Charles Moizeau w2sh at msn.com
Mon Sep 12 03:56:04 PDT 2011










In my most recent posting on this subject I said: 
"...I'm puzzled by how the feed current at the base of any antenna, regardless of its length, will always be at a maximum at its base.  A half-wavelength antenna presenting a few thousand ohms of input impedance at its base would, I think, have difficulty accepting "maximum FEED current" there..." Perhaps it was because the hour was late, but I completely disregarded the universal use of matching devices at a feedpoint in order to overcome feed difficulties.  Apologies for the omission. In my case, with an inverted L antenna having a total length of 170 feet, just a series capacitor at the base feedpoint with a value of about 255 pF gives me an SWR of 1.15 to 1.  However, that figure is measured at the shack, about 100 feet away. Also, I transitioned the subject matter too swiftly from feedpoint impedance to radiation resistance.  The two are different and should not be confused with each other. 73, Charles, W2SH       

 		 	   		  


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