What about an end fed Zepp? Fed with open wire. I have read that it thinks
there is an immaginary 1/4 wave section where the feeder is terminate at a
dead or insulator point. I know this is a high impedance point on a zepp.
A half wave vertical would need no radials on that resonant frequency.
WA5MUE
----- Original Message -----
From: "Al Williams" <alwilliams@olywa.net>
To: <towertalk@contesting.com>
Sent: Monday, May 23, 2011 11:45 AM
Subject: [TowerTalk] Fw: Fw: Why radials improve radiation!
>
> ----- Original Message -----
> From: "Al Williams" <alwilliams@olywa.net>
> To: "WA8JXM" <wa8jxm@gmail.com>
> Sent: Monday, May 23, 2011 9:43 AM
> Subject: Re: [TowerTalk] Fw: Why radials improve radiation!
>
>
>> No, it doesn't help me understand because it just rephrases what I tried
>> to say in 2b of my question.
>>
>> In case of the dipole, if the two sides are of equal length then it would
>> seem there is a place for the charge and discharge to be identical.
>> However if the feedpoint is moved off-center the radiation according to
>> EZNEC remains the same. Where is the current to charge/discharge the
>> shorter side (to make up for the shorter wire) going?
>>
>> k7puc
>>
>>
>> ----- Original Message -----
>> From: "WA8JXM" <wa8jxm@gmail.com>
>> To: "Al Williams" <alwilliams@olywa.net>
>> Sent: Monday, May 23, 2011 9:26 AM
>> Subject: Re: [TowerTalk] Fw: Why radials improve radiation!
>>
>>
>> I don't know if this will help or not, but I'll try (at least according
>> to
>> my thinking):
>>
>> If you take a light bulb and run one wire to it from a battery, obviously
>> the bulb will not light up. Why? because there is no place for current
>> to go to.
>>
>> Likewise with an antenna. If you only have one connection (the center
>> conductor), where will the current flow to? It needs either another
>> element (such as the second side of a dipole), or a ground connection .
>> Then you have two wires to accept your power.
>>
>> A good set of radials provides a good place for the rest of the circuit
>> to
>> send it's current.
>>
>> Does that help any?
>>
>> Ken WA8JXM
>>
>> On May 23, 2011, at 11:55 AM, Al Williams wrote:
>>
>>>
>>> ----- Original Message -----
>>> From: Al Williams
>>> To: SteppIR@yahoogroups.com
>>> Sent: Wednesday, May 18, 2011 8:23 AM
>>> Subject: Why radials improve radiation!
>>>
>>>
>>> Help, Help!
>>> There have been many, many postings on how to set up the radials but
>>> never a discussion on why or how radials actually effect the radials as
>>> it seems to be "beyond the scope....".
>>>
>>> It is pretty easy to understand why from a circuit current loop
>>> viewpoint
>>> i.e. the transceiver power output is divided between the radiation
>>> resistance and the ground resistance (ignoring connector, coils, and
>>> wire
>>> resistance).
>>>
>>> 1. However the radiation resistance is a make-believe or psuedo
>>> resistance apparently derived from calculations of subtracting ground
>>> system power (system loop current x ground resistance) from the
>>> transceiver power output. Thus, since the loop current is known and the
>>> remaining power is known, then the radiation resistance can be
>>> calculated?
>>>
>>> But his seems analagous to lifting oneself up by pulling up on ones
>>> bootsraps!
>>>
>>> 2a. For vertical antennas, it is said that there is no reflection
>>> (radiation) from the ground system.
>>> It isn't very clear why, horizontal or vertical polarization or ?
>>> 2b. It is also that radiation is a result of the changing state of the
>>> electrons in a material, caused by the changing current intensity. Thus
>>> the material is acting like a capacitor (charging and discharging as the
>>> current changes. For the material to charge/discharge there must be an
>>> opposite charge/discharge somewhere?
>>> 2c. Is this "somewhere" the ground or the radials? Do the radials allow
>>> the antenna material to charge/discharge to greater amounts? Why and
>>> how?
>>> 3. If 2c is true then "heating up the ground comments" hides what is
>>> really happening?
>>>
>>> help help
>>>
>>> k7puc
>>
>
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