# Dipole antenna

Discussion in 'Electronic Basics' started by thejim, Jan 9, 2006.

1. ### thejimGuest

What do we mean by saying that a dipole antenna is electrically short?

2. ### Anthony FremontGuest

It means that the antenna is exhibiting capacitive reactance to the
signal being applied. Adding inductance can cancel that out.

3. ### Phil AllisonGuest

"Anthony Fremont"

= a congenital autistic cretin

** Idiot.

It means the dipole antenna's width is less than a half wavelength of the
frequency.

** Has no impact on the fact it is "electrically short" and hence an

You fucking brainless Texas Twat.

......... Phil

4. ### Anthony FremontGuest

Speak for yourself phil. Oh, I guess you already are.
Electrically that is, not necessarily physically. You do know about
velocity factor, right phil?
Radiation efficiency has very little to do with any of this. You're way
out of your element on this one phil, but keep going though. I'd really
like to see what kind of nonsense you can spew on antenna and
transmission line theory.
Who's stalking now?

5. ### Phil AllisonGuest

"Anthony Fremont"
= a congenital autistic cretin

** FUCKING Idiot.

** IRRELEVANT to the antenna - FUCKHEAD !!

Fremont is a PIG IGNORANT ASSHOLE.

A vile, anencephalic, autistic Texas Twat.

Millions of these evil PUKEs down there.

]

......... Phil

6. ### Anthony FremontGuest

It's still true phil, no matter how many times you reply to it with
ad-hominem attacks. I can only hope that someone else that knows
something about antennas will step into this, lest some poor newbie
That's precisely how it works. It has practically nothing to do with
physical length other than that's one of the multipliers used when
calculating the electrical length.
Really now phil, you know even less than I suspected. Velocity factor
applies to all of it, especially the antenna itself.
Where is your disputing evidence phil?
Why don't you try providing some facts phil? Instead of name calling,
why don't you show us all some evidence to back up your libelous claims?
I guess that was it. Typical spastic fit when you don't have an answer,
huh phil? I bet you have never made a single transmitting antenna for
HF or VHF. If you had, you'd probably be keeping your mouth shut now.

7. ### John PopelishGuest

It means that it has a resonant frequency a little higher than what is
being applied to it.

8. ### Anthony FremontGuest

Thanks John. I would add for the OP's benefit that dipoles cut using
the standard formula will always come out electrically long since the RF
doesn't travel at the full speed of light thru the antenna elements.
Therefore they will need to be trimmed to resonance to accommodate that
fact. A great number of other things will also affect this process
(basically anything that you can think of ;-)

One major player that must be considered is the velocity factor of the
material used for constructing the antenna elements. For example,
dipole elements made from insulated wire will exhibit a different
velocity factor if the insulation is removed vs. leaving it on.
Therefore, they will need to be trimmed to different lengths to obtain
resonance at the same frequency.

9. ### Phil AllisonGuest

"Anthony Fremont" = a congenital autistic cretin

** No it is not - and you are an IDIOT.

** WRONG - IDIOT .

** WRONG.

** Any good text of antenna theory will confirm what an the term
"electrically short" antenna refers to.

They can be externally tuned to resonance but still have less radiation
efficiency that a naturally resonant antenna.

** The PIG IGNORANCE and PIG ARROGANCE are GLARING .

** YOU are posting all the evidence - ASSHOLE.

** PISS OFF - you know nothing, libelling SCUMBAG !

......... . Phil

11. ### Anthony FremontGuest

Leave it to you to find the obscure, extreme case to try and save some
face. In this particular case you are right, efficiency is extremely
hampered by the incredible shortness of the antenna and inductance will
not make the antenna work any better, it would make a transmitter very
happy though. Why you immediately assume the OP is referring to MF
antennas is beyond me.

12. ### Phil AllisonGuest

"Anthony Fremont" = AUTISTIC LYING PIG

** WRONG AGAIN - IDIOT !!!!!

** WRONG AGAIN - IDIOT !!!!!

The exact same concepts apply to "electrically short" VHF and UHF antennas.

** PISS OFF - YOU BLOODY CRETIN !

......... Phil

13. ### Anthony FremontGuest

Do you really think that people don't see the butcher job you do when
snipping the context out of everything as you trim. Or the way you
continually twist things by interjecting your own set of completely
fabricated working conditions in some childish attempt to erase the
lunacy from some previous foolish statement you made. Face it phil, you
don't know jack about antennas OR transmission lines, why can't you

You can keep saying that I'm wrong, and call me as many names as you can
think of, but it won't change the truth. To the best of my knowledge
all of the statements I have made are true and correct. I've built
plenty of antennas phil. At least plenty enough of them to know that if
you think that you will get by with book theory and strictly applied
formulas to do it, you're gonna be on a short road to failure. I'm not
saying that I'm an expert on the subject, but I do know something about
it.

FYI, I own a few well worn ARRL Handbooks (including my first one from
1974), the Antenna Compendium and many other radio THEORY books
including a Sam's Radio Handbook. I have also APPLIED some of this
material, that's why I know how far theory can deviate from reality on
this subject. Now tell us all again philth just how much education and
experience you have regarding the subject, dumbass.

PS: I love my MFJ-259B. ;-)

14. ### Phil AllisonGuest

"Anthony Fremont"

= Lying, autistic, Texas asshole

** So you are fuckwit radio ham ??

Explains it all really.

........ Phil

15. ### Anthony FremontGuest

Now tell me something I don't already know. Given that the OP didn't
specify that he was talking about very short antennas (1/10 lambda or
less), I naturally didn't jump to the conclusion that he was. I,
perhaps wrongly, assumed he wanted to know what the term "electrically
short" meant. In these extreme cases that you like to bring up, the
efficiency is bad and it pretty much stays that way regardless of what
you attempt. Capacity plates (or hats as many like to call them) and
they still radiate like crap (orders of magnitude more poorly) compared
to even a 1/4 wave. Just tune around the 160m or even 80m bands
listening for the mobile stations. They're there, but just try to hear
them.

16. ### Anthony FremontGuest

"Phil Allison" scrawled

17. ### Phil AllisonGuest

"Anthony Fremont"

** Failed the test of relevance nor made any sense.

YOU can go to HELL - IDIOT.

......... Phil

18. ### Phil AllisonGuest

"Anthony Fremont"

** So you are know nothing, fuckwit radio ham ??

Explains it all really.

........ Phil

19. ### Anthony FremontGuest

IKYABWAI YAAAWWWWNNNNNNN You're really getting boring now philth.
Even darkmatter was able to put up a more fact based argument than you.
Not to mention that Boki beats you hands down on sentence construction
and clarity.

So how would being a ham "explain it all"?

HAND

20. ### Phil AllisonGuest

"Anthony Fremont"

= autistic, illiterate bloody IDIOT

** So you are *know nothing, fuckwit radio ham * ??

Explains it all really.

........ Phil