Greetings Holger!   
      
    HG>> Roy, you are confusing the issue. While Tom is correctly writing   
    HG>> about director lengths you are suddenly writing about radials.   
      
    RW>> What's confusing about that? Directors are radials and vice versa...   
      
    HG> Nowhere have I heard or read that a Yagi antenna has radials.   
      
   Well, you have heard it now.   
      
    HG> A yagi has a driven element and parasitic elements of which the ones   
    HG> in front are named directors and the one(s) behind the driven element   
    HG> are named reflector(s).   
      
   All radials...the terminology used doesn't mean much...They could be a   
   driven element, which is a dipole. Or they could be directors or a   
   reflector, which are parasitic elements or radials.   
      
    RW>> The other issue is that Tom is thinking that a yagi and a LPA are   
    RW>> one and the same antenna, when in fact they are two different   
    RW>> designs and each is engineered differently.   
      
    HG> Agreed.   
      
    RW>> i.e. The LPA antenna normally consists of a series of dipoles   
    RW>> (directors, radials) positioned along the antenna axis, which are   
    RW>> spaced following a logarithmic function of the frequency.   
      
    HG> Actually there are two different kinds of log periodic directive   
    HG> antennas.   
      
    HG> The LPA antenna you are writing about has several driven elements   
    HG> that are fed by crossing the feed to every element next in line. The   
    HG> lengts of the driven elements are staggered to achieve a broader   
    HG> bandwidth.   
      
    HG> I know this type particularly well because I have built and measured   
    HG> several concepts for both 2 m and 70 cm and used them actively.   
      
   Cool.   
      
    HG> Behind the stack of driven elements there usually is a reflector and   
    HG> in front of the driven elements directors.   
      
   That's the theory, anyway. And the one that Tom is advocating. IMO, it is   
   not a true LPA.   
      
    HG> This antenna is often called a KLM-yagi because the KLM company was   
    HG> the first to manufacture antennas of thes kind originally presented   
    HG> in an article in QST.   
      
   I haven't ever read that magazine. It is too much ARRL oriented and I'm   
   not a fan of that organisation.   
      
    HG> The other kind of LPA is one built on two booms insulated from each   
    HG> other and fed from (often) the front end. The elements are not   
    HG> dipoles per se but are quarter wave length directors staggered on the   
    HG> twin booms so that each director is only half of a director the   
    HG> second half of it being placed where the next director (in a yagi)   
    HG> should have been.   
      
   Correct and this is the subject of this LPA discussion.   
      
      
       Have a day!   
      
            R\%/itt - K5RXT   
      
   --- GoldED+/W32 1.1.5-31012   
   --- D'Bridge 3.99   
    * Origin: HAM Radio, aka Amateur Radio. 804? Over! (1:387/22)