LinkBack Thread Tools Search this Thread Display Modes
Prev Previous Post   Next Post Next
  #11   Report Post  
Old March 23rd 06, 04:12 PM posted to rec.radio.amateur.antenna
Yuri Blanarovich
 
Posts: n/a
Default Current through coils


wrote in message
Let's focus on one thing at a time.

You claim a bug cather coil has "an electrical length at 4MHz of ~60
degrees". That concept is easily proven false, just like the claim a
short loaded antenna is "90-degree resonant". Both can be shown to be
nonsense pictures of what is happening.

Assume I have a 30 degree long antenna. If the loading inductor is 60
electrical degrees long, I could move it anyplace in that antenna and
have a 90 degree long antenna.

We all know that won't happen, so what is it you are really trying to
say?

73 Tom


OK lets get me some educating here.
I understand that, say quarter wave resonant vertical (say 33 ft at 40m) has
90 electrical degrees.
Is that right or wrong?

The current distrubution on said (full size) vertical is one quarter of the
wave of 360 deg. which would make it 90 degrees. Max current is at the base
and then diminishes towards the tip in the cosine function down to zero.
Voltage distribution is just opposite, min at the base, feed point and max
at the tip. EZNEC modeling shows that to be the case too.
Is that right or wrong?

If we stick them end to end and turn horizontal, we get dipole, which then
would be 180 deg. "long" or "180 degrees resonant".
If not, what is the right way?

If I insert the coil, say about 2/3 up (at 5 ft. from the bottom) the
shortened vertical, I make the coil size, (inductance, phys. dimensions)
such that my vertical will shrink in size to 8 ft tall and will resonate at
7.87 MHz.
I learned from the good antenna books that this is still 90 electrical
"resonant" degrees.
Maximum of current is at the feed point, minimum or zero at the tip.

If you stick those verticals (resonant) end to end and horizontal, you get
shortened dipole, with current distribution equal to 180 degrees or half
wave. Max current at the feed point, minima or zero at the tips. (RESONANT
radiator)

How many electrical degrees would that make? How do you arrive at that?
Why is this a nonsense?

Can we describe "pieces" or segments of the radiator as having proportional
amount of degrees corresponding to their physical length, when excited with
particular frequency?

If I can be enlightened about this, we can go then to the next step.

Answers, corrections please.

Yuri, K3BU


 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules

Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Current in Loading Coils Cecil Moore Antenna 2 March 5th 06 08:26 PM
FCC: Broadband Power Line Systems Paul Policy 0 January 10th 05 05:41 PM
FS: sma-to-bnc custom fit rubber covered antenna adapter Stephen G. Gulyas Scanner 17 December 7th 04 06:42 PM
Current in antenna loading coils controversy (*sigh*) Roy Lewallen Antenna 25 January 15th 04 09:11 PM
Current in antenna loading coils controversy Yuri Blanarovich Antenna 454 December 12th 03 03:39 PM


All times are GMT +1. The time now is 04:16 PM.

Powered by vBulletin® Copyright ©2000 - 2025, Jelsoft Enterprises Ltd.
Copyright ©2004-2025 RadioBanter.
The comments are property of their posters.
 

About Us

"It's about Radio"

 

Copyright © 2017