In a message dated 05-26-14, Tom Walker said to Holger Granholm:   
      
   Hi AGN Tom,   
      
   After I had sent you my reply this morning I came to think about your   
   apparent mixup of the LPDA (Log Periodic Dipole Array) and the LPYA (Log   
   Periodic Yagi Antenna).   
      
   TW>And no matter the implimentation, Double boom or Single boom with   
   TW>insulated elements and crosssover wiring it is Still a Real LPDA   
      
   Nope, a single boom antenna with insulated driven elements fed by   
   crossed phasing lines is the LPYA. This type of antenna is used to   
   broaden the frequency range of an antenna for an amateur band or a   
   group of TV channels.   
      
   The ham bands from 28 MHz and up are so wide that it is difficult to   
   cover the entire frequency range and have a decent SWR across it with   
   a standard yagi design.   
      
   This type of antenna can also be used to cover various groups of TV   
   channels like the low VHF channels, the high VHF channels and the UHF   
   channels. Different antennas for different channel groups.   
      
   OTOH, the LPDA antenna can be designed to cover a large frequency area.   
   For example 50 to 1300 MHz as you mentioned if made long enough or with   
   steep element taper.   
      
   This antenna is ALWAYS built on a double boom and all the driven   
   elements are mounted non-insulated directly to the booms. Notable is   
   also that the driven elements mounted to the booms are actually a   
   quarter wavelenght on each boom, thus making the combined length a half   
   wavelength at a certain wavelength (frequency).   
      
   Usually the elements are staggered on the booms so that the next element   
   is halfway to the following one but I have seen LPDA's with the elements   
   inline with the one on the other boom. And the booms are isolated from   
   each other and consequently have to be mounted to a non-conductive mast   
   or insulated to a metal mast.   
      
   By way of the tapered length of the elements they are resonant at diffe-   
   rent frequencies and by choosing the longest elements for the low end   
   frequencies and the shortest elements for the highest frequencies the   
   frequency range of the antenna is set to the decided frequency area.   
      
   The feeder (coax) is fed from the rear through one boom which also can   
   act as a balancing device. The shield is connected to the front end of   
   this boom and the center conductor to the other boom.   
      
   73 de Sam, OH0NC   
      
   aka Holger   
      
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