[HQRP] Question on Ed's Grounding article

[Rick Hiller]

Morning, Folks,

I have a question on the article that we all got a copy of at Saturday's 
HQRP meeting.  CQ January 2002 Page 39

Can anyone decipher this paragraph for me????

" In practice we have a major problem using quarter-wave radials, since 
length tolerances are always finite, making it impossible to maintain 
current equality whilst tuning through resonance.  So if a quarter-wave 
radials are a "no-no", what's the practical alternative?"


The first sentence is the one that boggles the gray matter..... I realize 
that he wants (or 'Has to') maintain current equality in the 2 radials in 
order to avoid radiation from them...BUT why are 1/4 wl radials more 
difficult to maintain current equality than lesser length radials...which 
he goes onto apply later in the article???

This is my main question !  Am I reading his statement correctly?

Further......
My guess is that by using a coil at the current maximum point of the 
standing wave that this coil has equal current flow (for both radials) and 
that the shortened 1/8 wl radials will only be handling the greater than 
'45 degree' values of standing wave current which are less and less as 90 
degrees (1/4 wl) electrical radial is approached?   Less length is also 
less influence by the 'earth' too.

Assuming if my assumption is correct (and it may not be... :-) ) how then 
is the coil portion of the radial system used to 'capture' antenna return 
currents...maybe the linear portions of the radials, no matter how small do 
all the work.

I have modeled the thought process and so far so good.  In free space 
things work out as he states but when moving the model close to the earth I 
have yet to check the skewing of the omni-directional pattern  (if any) due 
to the use of only 2 radials.

A fellow ham has my Moxon book and my ARRL Antenna Compendium 6, which also 
has an article on short and low quantity radial systems so I haven''t been 
able to follow that thread yet.

Note that one quantity he does not mention is 'field strength'...the dBi 
scale within EZNEC...this varies greatly for the various girations he takes 
the vertical dipole through...varying in the minus direction most of the time.

Thank you in advance for your answers....regards...Rick ...W5RH




Rick Hiller.....W5RH
Houston, Texas 

---
Send e-mail to 'listar@stevens.com' with subject:

  'unsubscribe hqrp'  to unsubscribe from this list
  'subscribe hqrp'    to subscribe from this list
  'help'              for more information

Send e-mail to 'dave@stevens.com' to contact a list administrator