The 1/4 wave groundplane is a balanced antenna (1/4 up and a 1/4 out), the 5/8 isn't. Different antennas, different rules.FL Native said:
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Building a 5/8 wave antenna
- Thread starter Cat Driver
- Start date
ok so if i use a 5/8 ground plane and vertical radiator it would be balanced and then the ground plane would make a difference.
so your saying the only balanced antenna is one with equal length on the counter poise and the main radiator.
if that was true then why do multi element beams work. more ground than driver.
if that was true then why does Jay's antenna work so good with a 1/4 wave ground plane and 5/8th or so with that cap hat work so well.
i don't know the set up of an I10k but it does have a cap hat. which makes its electrical length even longer.
hmmmm interesting
:?
so your saying the only balanced antenna is one with equal length on the counter poise and the main radiator.
if that was true then why do multi element beams work. more ground than driver.
if that was true then why does Jay's antenna work so good with a 1/4 wave ground plane and 5/8th or so with that cap hat work so well.
i don't know the set up of an I10k but it does have a cap hat. which makes its electrical length even longer.
hmmmm interesting
:?
I thought the cap hat shortened it electrically ?????
And someone please explain the design of the Sigma 4 (I think it's the antenna which looks supported in the middle of an ice cream cone...
..inverted radial design ) and its efficiency plus' and minus'
73's
And someone please explain the design of the Sigma 4 (I think it's the antenna which looks supported in the middle of an ice cream cone...
..inverted radial design ) and its efficiency plus' and minus'73's
The 5/8 is a different antenna and will not work as a 1/4 wave does. Make it 3/4 wave and have some fun!
I looked for the website that addressed increasing the length of the radials to 5/8 wave but was unable to find it.
A capacity hat electrically LENGTHENS the antenna.
Multi-element beam with more ground than driver......WHAT?!
Did someone mention the Sigma IV?!!!! Well.......
FL, you need to pick up a book and learn about antennas. The confusion will go away......hopefully.
Why make a 5/8 wave antenna when you can buy a Maco for less than $100.00?!
I looked for the website that addressed increasing the length of the radials to 5/8 wave but was unable to find it.
A capacity hat electrically LENGTHENS the antenna.
Multi-element beam with more ground than driver......WHAT?!
Did someone mention the Sigma IV?!!!! Well.......
FL, you need to pick up a book and learn about antennas. The confusion will go away......hopefully.
Why make a 5/8 wave antenna when you can buy a Maco for less than $100.00?!
Master Chief said:
I know the web site your talking about I can't find it either it was great info on his experiments on 1/4, 1/2, & 5/8 with radials including 90deg and sloped from 1/8 to 5/8 ground radial length in the end I believe he found a 5/8 radiator with one sloped 5/8 length ground radial to be the best at gain and take off angle although it didn't say what he used for matching network dang it. I agree the price of a commercial is cheaper then trying to build a vertical antenna buy the time you add upper c o p p e r, stainless steel, bake-o-lite, or carbon fiber is a lot cheaper now on beams or wire antennas that is a different story.
Now for Sigma IV isn't that just a version or different way to build a J pole like the Astro Plane looks like a version of one just a different way to put it all together and make it work?
Antennas and antenna theory generally all stems from the basic half-wave, center-fed dipole, probably the most basic of all antennas.
A quarter-wave vertical is only half of a dipole. It needs that missing quarter-wavelength to get back to its dipole roots. The radials take care of that. If the radials are a little longer than 1/4 wavelength, the ideal radiation pattern may be a little bit skewed, just as an off-center fed doublet's would be.
An end-fed 5/8-WL vertical, as Mr. Clean said, will have a considerably higher feedpoint impedance than a dipole or a 1/4WL vertical with radials. It will "work" only if this impedance is transformed to something close to the characteristic Z of the feedline, and that's what the matching system at the base does. The Ringo Ranger is a perfect example of that type of matching.
One thing a 5/8 WL vertical does NOT need is a ground plane/radials/counterpoise. Why? Because it's already over 1/2 WL. It's met the basic requirements. A half wave of input can be graphically overlaid on it, with a bit left over which increases the feedpoint Z. The matching system cancels that out.
A quarter-wave vertical is only half of a dipole. It needs that missing quarter-wavelength to get back to its dipole roots. The radials take care of that. If the radials are a little longer than 1/4 wavelength, the ideal radiation pattern may be a little bit skewed, just as an off-center fed doublet's would be.
An end-fed 5/8-WL vertical, as Mr. Clean said, will have a considerably higher feedpoint impedance than a dipole or a 1/4WL vertical with radials. It will "work" only if this impedance is transformed to something close to the characteristic Z of the feedline, and that's what the matching system at the base does. The Ringo Ranger is a perfect example of that type of matching.
One thing a 5/8 WL vertical does NOT need is a ground plane/radials/counterpoise. Why? Because it's already over 1/2 WL. It's met the basic requirements. A half wave of input can be graphically overlaid on it, with a bit left over which increases the feedpoint Z. The matching system cancels that out.
lords
Active Member
besides your great words of wisdom and internet searching...do yous ever do any hands on stuff?????
try it..you would be amazed at what you can do with any antenna...and not just book math...and past theory!
try it..you would be amazed at what you can do with any antenna...and not just book math...and past theory!
At every node, the sum of all currents entering a node must equal zero. What this law means physically is that charge cannot accumulate in a node; what goes in must come out.
(kirchoff's law of current)
you can't force power or current into a single terminal load. in the absence of a counterpoise that second terminal will appear at the connection of the outer shield of the feedline and/or the matching network itself but the network will not provide the necessary balance of current between itself and the radiating element, particularly when the antenna moves away in either direction from resonance. when this occurs ground currents increase. (easily measured with an rf ammeter) in the absence of any second terminal counterpoise these currents will flow on the outer shield jacket instead and create problems of their own. the further the antenna moves from resonance the more counterpoise is required to allow increasing ground current levels to return to the node.
in an end fed antenna, common mode current flowing into the end of the radiator MUST be returned to the OPPOSITE terminal of the generator. ideally the returned current always equals the common mode current flowing into the antenna end.
lords
Active Member
74IN said:
challenges??? I think you need to see a DOC for your problem I wasn't asking nothing I was telling.and it doesn't have nothing to do with challenges...DUH!
not to say I don't even see you in this posting..another chair sitter huh!