I do not post much on 1/4 wave threads because I often get myself in trouble with this topic because of my choice of words, but....
Posted By WW:
Posted By BM:
Posted by 6 Liter :
Posted by Marconi:
Posted By DOC :
Posted By BM:
Posted By Marconi :
Posted By Gamegetter:
I would Keep going, But there seems to be a pattern here.
This Post I agree with 100%
Posted By gamegetter.:
I know the example I am about to talk about is a Base antenna, but just to think about, ....the I10-K is tuned by setting the length of the antenna and THEN adjusting the trombone for best bandwidth/SWR.
( then re-read the above and take out the word trombone and insert the words feed-point for just a second)
Now Back to this:
Amateur Quarter Wave Ground Plane Antenna Calculator
The numbers are there, no mater how many times you try it.
And what DOC is saying about
""just because it shows good SWR don`t mean that the antenna is resonate""
many antennas can be the correct length, but exhibit SWR that is real bad, because of several factors.
Design
Feed
Location
Lack of Good Ground plane ( iF the design needs one)
Then Look at this Image From The K0BG. com web site.
many Guy`s, look at that and go...
W T F ?
That is BS....How can that work ??? You just shorted the Coax to ground!!!
That is a dead short!
I will finish...
An antenna Can show Good SWR and yet NOT be the correct Length.
An Antenna CAN be the correct Length and show BAD SWR.
This is why we need to MATCH the feed point of the antenna.
regardless of the SIMPLE idea of a 1/4 wave mobile set-up, it can often be complicated because there are so many factors that are different in a mobile mounting set-up.
RF is a Strange thing, Well...No RF is a Complex thing......
R= X= Ohms.......
SWR is but one thing in the whole picture, and in most cases it will get you by, because as long as you radio is happy with what it see`s at the coax connector on the back of the radio, it has that warm fuzzy everything is good feeling.
And "most" of the time that works well.
73
Jeff
