Dipole antenna

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

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

"thejim" wrote

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

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

short?

Speak for yourself phil. Oh, I guess you already are.

the

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?

the

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 believe your nonsense.

of

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.

an

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.

short?

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.

"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 inefficient radiator.

You f****ng brainless Texas Twat.

........ Phil

short?

is

that

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.

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 simply admit that?

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. ;-)

"Anthony Fremont" = a congenital autistic cretin

** FUCKING Idiot.

** WRONG - FUCKHEAD.

** IRRELEVANT to the antenna - FUCKHEAD !! ** WRONG - FUCKHEAD !!!

Fremont is a PIG IGNORANT ASSHOLE.

A vile, anencephalic, autistic Texas Twat.

Millions of these evil PUKEs down there.

]

........ Phil

antennas.

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 loading coils help to match the impedance and/or improve bandwidth, but 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.

"Phil Allison" scrawled

You didn't answer my question.

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

Well Phil, I don't know how to tell you that, but, Anthony is right...

Thanks Vanc, but Phil already knows it all.

"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

"John Popelish"

** The OP is more likely considering the term in relation to a dipole that is undersized by a fairly large degree.

......... Phil

"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