Half Wave Vertical vs. Half Wave vertical Dipole??

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Rob » Mon, 25 Oct 1999 04:00:00

Which antenna is a better DX antenna at low elevations - the wave wave
vertical or the half wave vertical dipole??
(I understand that the half wave vertical dipole is the easiest to feed with
50 ohm coax but I don't mind building a matching system for a half wave
vertical if it is worth it for DX)

Has anyone had on air experience with both types of antennas??

73's

Rob

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by dm » Mon, 25 Oct 1999 04:00:00


I wager we all have, OM! As personal as your tooth brush..the choice is.
I'll take horizontal over  vertical every day I  CAN GET IT HIGH ENOUGH.  My
current, fixed, wire, two element  40 M beam  is at 3/8 wave. I don't think
I'd have tried  that, but  it was easy to do, so I dropped down my 30 M
same style beam, and hung this one in that spot. So  far the results are
super...amazing, in fact. My phased verts on 40 weren't  as good...I don't
think, and man! Did  they collect electric fence racket!   Good luck with
either...you probably wont be able to make YOUR choice until you've tried
both.    "DM"
 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by William F. Hage » Mon, 25 Oct 1999 04:00:00

I presume you mean a halfwave endfed vertical verses a halfwave vertical
dipole.
Bothe should have the same radiation pattern, and hence, the same gain.
A vertical dipole is better than a vertical quarterwave because there is
a null pointing straight up, less cloud warming if the antenna height is
correct. As for the endfeed versus feeding in the center as a dipole,
feeding in the center gives a 50-75 0hm match to coax, can incorporate
either a ***or current balun, you need to engineer supports to hold
the ends in place, and have high voltage at the lower end, so keep clear
to prevent arcing.
As for the end feed vertical, essentially a j-pole, you will probably
use the quarterwave match, which can be used as the support for the
lower end, and can be grounded at the end, but makes the antenna length
a quarterwavelength longer (higher). Also a ***balun (several coils
of coax) to minimize common mode current and radiation from the
feedline.
kc6ufe


> Which antenna is a better DX antenna at low elevations - the wave wave
> vertical or the half wave vertical dipole??
> (I understand that the half wave vertical dipole is the easiest to feed with
> 50 ohm coax but I don't mind building a matching system for a half wave
> vertical if it is worth it for DX)

> Has anyone had on air experience with both types of antennas??

> 73's

> Rob

--
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Half Wave Vertical vs. Half Wave vertical Dipole??

Post by dm » Mon, 25 Oct 1999 04:00:00

I'm with KC6UFE...and would add that  a  full  half wave "radiator"  is
something like  1.5 db stronger in field intensity  than a quarter wave
"radiator". This is  due to a full current "loop"  on it  versus only a half
a current loop  on the shorter one.  It is the same old story...Field
intensity  is proportional to the current flowing......73  "DM"
 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Brian Kel » Mon, 25 Oct 1999 04:00:00


>Which antenna is a better DX antenna at low elevations - the wave wave
>vertical or the half wave vertical dipole??
>(I understand that the half wave vertical dipole is the easiest to feed with
>50 ohm coax but I don't mind building a matching system for a half wave
>vertical if it is worth it for DX)

If you have a good way to support a vertical dipole and a good way to
pull the coax feedline away from the antenna at 90 degrees the dipole
is much simpler to install and feed and will perform the same or
better than and end-fed vertical.
Quote:

>Has anyone had on air experience with both types of antennas??

I have. I've put up several of both. I'll take the dipole if I have a
big tree handy. The verticals go up on open real estate where they
usually have to be ground mounted. Beyond that there are no
differences.
Right now I have a 20m dipole strung from the top of a tree, the
bottom end is around ten feet off the ground. It works fine as an
antenna, I can work just about any dx I can hear with a barefoot xcvr
and I can hear just about any signal the guys with the beams in this
area are hearing. But I would not call it a competitive antenna on
20m, ya gotta work to get thru the cw pileups. Any tribander at 50 ft
will spank it. The big downside is that the thing is a noise magnet. I
also have a 475 ft horizontal end-fed wire strung thru the trees at
around 40-50 ft. When I tune a weak signal with the agc / s-meter on
and switch back and forth between the two antennas the noise level
with the vertical is a full s-unit higher than I have with the
longwire and the longwire gives me a little less than an s-unit of
gain. That's 10 or so dB or almost two s-units more noise with the
vertical. It would probably be a lot worse than that if I was in
southern climes like Florida where there is a lot of qrn.
Quote:

>73's

>Rob

Brian Kelly w3rv
 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Fracten » Tue, 26 Oct 1999 04:00:00

Quote:>I'm with KC6UFE...and would add that  a  full  half wave "radiator"  is
>something like  1.5 db stronger in field intensity  than a quarter wave
>"radiator".

It IS?

Quote:> This is  due to a full current "loop"  on it  versus only a half
>a current loop  on the shorter one.

That is incorrect. According to this logic,  an 1/8 wave, lossless dipole is 3
dB below a 1/2 wave lossless dipole.

According to this logic, an infinitesimal losslessloop has zero dBi, when in
fact is has 1.8 dBi.

This is very wrong.

Also,  over a large GP a 1/2 wave vertical has MORE than a
full "current loop".

Quote:> Funny,  It is the same old story...Field
>intensity  is proportional to the current flowing......73  "DM"

No; field strength depends on the current distribution and ohmic loss.

The question, as posed, is: a 1/2 wave VERTICAL over real ground better or
worse than a 1/2 wave DIPOLE just above real ground?

The answer to this is not obvious; if no one else gets back to you, I'll model
the two and tell you in a couple of days when I can free up a few minutes. My
speculation is that the 1/2 wave vertical, with a good radial system, over real
ground, has the higher f.s.

73
Chip n1IR

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by <nhbiw.. » Tue, 26 Oct 1999 04:00:00

Dear OM's

the question is not so easy to answer.
Over ideal ground, a ground mounted (insulated) half wave vertical is 1.7
dB over a ground mounted quarter wave. This is because in the case of the
half wave, the "upper" and "lower" part of the sineshape current
distribution add up in phase in some directions.
Over real ground, the situation is more complicated. If one wants to have
high gain into low elevation angles, one must use a very big radial
system. This is because the resultant field strength adds up from a direct
component and a component reflected from the ground. Over real ground,
this reflection is lossy and there is a phase shift. This is in connection
with the so called "pseudo-Brewster" angle. In optics, you observe, using
vertical polarized light, that, under some angle, there will be no
reflection from a horizontal oriented dielectric surface. This is the so
called Brewster angle, where the light enters completely the dielectric
medium. If the medium is lossy, all the light is absorbed. The same is
approximately true for radio waves, with the possible exception, that the
assumption of plane waves does not hold very close to the antenna.
The consequence of this Brewster effect is, that you have to improve the
conductivity of your ground very far away from the antenna. For example if
you want a high gain at 20 Degrees, you must provide a hgh conductive
surface at a distance of (lambda/4)/tan(20 Degress) approx 0.7 * lambda
away from the antenna, assuming that the current loop is at 1/4 lambda.
This is true for the vertical dipole and the base fed as well. Because of
the high impedance of the end fed half wave, a good ground is not
important to increase the efficiency.
Using the above assumptions, I would expect no measurable difference
between the vertical dipole and the base fed half wave vertical.

Slight differences might occur because of a slightly modified current
distribution for the base fed vertical, which is slightly different from
the center fed dipole.

I remember modelling the case of a half wave vertical and a quarter wave
vertical over a ground system consisting of 120 quarter wave radials on
average ground (using a MININEC based program with all the inaccuracies
of MININEC) and found, that the quarter wave was several dB better than
the half wave for low elevation angles. So if I had the space I would put
up a quarter wave vertical over a relatively small (in terms of diameter)
radial system. If you can put up your vertical about one wavelength over
the ground, you can get strong radiation below the brewster angle. This is
because for waves striking a lossy dielectric surface under angles below
the Brewster angle, the waves are reflected with a phase shift of about
180 Degress. The reflectivity can be very high in this case. For this
reason, the waves striking the ground under low angles behave similar to
horizontal polarized waves, so that the "the higher the better" crieria
holds. In this case a halfwave is better than a quarter wave (with same
height of current loop) and a 5/8 wave is little better than a half wave.

In this situation I would expect, that the center fed half wave is
slightly better than the base fed because of the more symmetric current
distribution, but I think that it is not worth the efforts one hat to make
to lead the feedline perpendicular to the antenne for at least one quarter
wave length.

Anyway I am looking forward to the results of simulations; perhaps one of
the people having access to NEC-4 can do this for us.

Vy 73

Ralf

DL 6 OAP

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Richard Harris » Tue, 26 Oct 1999 04:00:00

Question:
Is a 1/2-wave vertical over real ground better or worse than a 1/2-wave
dipole just above real ground?

The ARRL Antenna Book has patterns for perfect earth. We know that the
horizontal dipole would produce a doughnut of radiation around the
center of the wire were it not for the presence of the ground. The
ground`s proximity tends to cancel ground-level energy because
reflection from the ground is out of phase for the horizontal wire. A
horizontal dipole near the ground is mostly a cloud warmer. Between 1/4
and 1/2 wavelength elevation above ground the 1/2-wave dipole produces
radiation at useful angles for communications of several hundred to
maybe a thousand miles. Your mileage may vary. Lossy ground reduces the
radiation amplitude and distinction in the pattern shapes.

The ground reflection of a ground mounted vertical 1/2-wave antenna is
in phase with the radiator. Excellent low-angle radiation results. But,
the 30-degree elevation radiation is much less than that produced from
the horizontal dipole at 1/2-wave elevation. So, if you want to talk 200
to 700 miles, more or less, the horizontal 1/2-wave may be a better
antenna for you. For DX, the vertical 1/2-wave with a good ground system
would be hard to beat.

Best regards, Richard Harrison, KB5WZI

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Gray Frierson Haerti » Tue, 26 Oct 1999 04:00:00

Another way to look at the problem of getting good low angle radiation
from a vertical antenna, is to realize that radiation at low angles
(below 10 or 15 degrees) is going to tend to e*** ground wave
propagation and not spacewave (or skywave) propagation.  Over any ground
that you are likely to encounter on this planet (including sea water),
ground wave propagation is pretty lossy at HF.  Certainly lossier than
spacewave or skywave propagation.

I believe this is a restatement in different (functional) terms of what
Ralf is getting at in his post which is more descriptive of the physics.

Because of this, I believe that vertical antennas near the earth ar
doomed to mediocre performance at very low radiation angles (at HF).
This is not to say that they make poor antennas.  They are capable of
generating very strong skywave signals at angles of 15 to 45 degrees
(depending on length and ground system) and this will grab you lots of
good DX.

However, it is awfully hard to beat a horizontal dipole if is way off
the ground.  This is why most of the big gun SWBC stations use
horizontally polarized curtain arrays.  Nothing like stacking a bunch of
horizontal dipoles vertically to get you some gain sideways.  (c:

Gray


> Dear OM's

> the question is not so easy to answer.
> Over ideal ground, a ground mounted (insulated) half wave vertical is 1.7
> dB over a ground mounted quarter wave. This is because in the case of the
> half wave, the "upper" and "lower" part of the sineshape current
> distribution add up in phase in some directions.
> Over real ground, the situation is more complicated. If one wants to have
> high gain into low elevation angles, one must use a very big radial
> system. This is because the resultant field strength adds up from a direct
> component and a component reflected from the ground. Over real ground,
> this reflection is lossy and there is a phase shift. This is in connection
> with the so called "pseudo-Brewster" angle. In optics, you observe, using
> vertical polarized light, that, under some angle, there will be no
> reflection from a horizontal oriented dielectric surface. This is the so
> called Brewster angle, where the light enters completely the dielectric
> medium. If the medium is lossy, all the light is absorbed. The same is
> approximately true for radio waves, with the possible exception, that the
> assumption of plane waves does not hold very close to the antenna.
> The consequence of this Brewster effect is, that you have to improve the
> conductivity of your ground very far away from the antenna. For example if
> you want a high gain at 20 Degrees, you must provide a hgh conductive
> surface at a distance of (lambda/4)/tan(20 Degress) approx 0.7 * lambda
> away from the antenna, assuming that the current loop is at 1/4 lambda.
> This is true for the vertical dipole and the base fed as well.

> Vy 73

> Ralf

> DL 6 OAP

--
Telecommunications Engineering
Gray Frierson Haertig & Assoc.
820 North River Street, Suite 100
Portland, Oregon 97227
503-282-2989
503-282-3181  FAX

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by William F. Hage » Tue, 26 Oct 1999 04:00:00

the question makes no mention of a horizontal antenna, it asks for a
halfwave vertical versus a halfwave vertical dipole.


> Another way to look at the problem of getting good low angle radiation
> from a vertical antenna, is to realize that radiation at low angles
> (below 10 or 15 degrees) is going to tend to e*** ground wave
> propagation and not spacewave (or skywave) propagation.  Over any ground
> that you are likely to encounter on this planet (including sea water),
> ground wave propagation is pretty lossy at HF.  Certainly lossier than
> spacewave or skywave propagation.

> I believe this is a restatement in different (functional) terms of what
> Ralf is getting at in his post which is more descriptive of the physics.

> Because of this, I believe that vertical antennas near the earth ar
> doomed to mediocre performance at very low radiation angles (at HF).
> This is not to say that they make poor antennas.  They are capable of
> generating very strong skywave signals at angles of 15 to 45 degrees
> (depending on length and ground system) and this will grab you lots of
> good DX.

> However, it is awfully hard to beat a horizontal dipole if is way off
> the ground.  This is why most of the big gun SWBC stations use
> horizontally polarized curtain arrays.  Nothing like stacking a bunch of
> horizontal dipoles vertically to get you some gain sideways.  (c:

> Gray


> > Dear OM's

> > the question is not so easy to answer.
> > Over ideal ground, a ground mounted (insulated) half wave vertical is 1.7
> > dB over a ground mounted quarter wave. This is because in the case of the
> > half wave, the "upper" and "lower" part of the sineshape current
> > distribution add up in phase in some directions.
> > Over real ground, the situation is more complicated. If one wants to have
> > high gain into low elevation angles, one must use a very big radial
> > system. This is because the resultant field strength adds up from a direct
> > component and a component reflected from the ground. Over real ground,
> > this reflection is lossy and there is a phase shift. This is in connection
> > with the so called "pseudo-Brewster" angle. In optics, you observe, using
> > vertical polarized light, that, under some angle, there will be no
> > reflection from a horizontal oriented dielectric surface. This is the so
> > called Brewster angle, where the light enters completely the dielectric
> > medium. If the medium is lossy, all the light is absorbed. The same is
> > approximately true for radio waves, with the possible exception, that the
> > assumption of plane waves does not hold very close to the antenna.
> > The consequence of this Brewster effect is, that you have to improve the
> > conductivity of your ground very far away from the antenna. For example if
> > you want a high gain at 20 Degrees, you must provide a hgh conductive
> > surface at a distance of (lambda/4)/tan(20 Degress) approx 0.7 * lambda
> > away from the antenna, assuming that the current loop is at 1/4 lambda.
> > This is true for the vertical dipole and the base fed as well.

> > Vy 73

> > Ralf

> > DL 6 OAP

> --
> Telecommunications Engineering
> Gray Frierson Haertig & Assoc.
> 820 North River Street, Suite 100
> Portland, Oregon 97227
> 503-282-2989
> 503-282-3181  FAX


--
Please remove the word 'NOREPLY' from the email address, sorry for the
inconvenience, but it helps keep down the spam.
 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Dennis C. O'Conno » Wed, 27 Oct 1999 04:00:00

Hey Gray...
How does the young fella on a city lot get a horizontal dipole "way up in the
air" for 160 meters? Or, for that matter, a vertical half wave dipole?

In general, there has been a lot of dancing of angels on the head of a pin in
this thread...

Denny


> Another way to look at the problem of getting good low angle radiation
> from a vertical antenna, is to realize that radiation at low angles
> (below 10 or 15 degrees) is going to tend to e*** ground wave
> propagation and not spacewave (or skywave) propagation.  Over any ground
> that you are likely to encounter on this planet (including sea water),
> ground wave propagation is pretty lossy at HF.  Certainly lossier than
> spacewave or skywave propagation.

> I believe this is a restatement in different (functional) terms of what
> Ralf is getting at in his post which is more descriptive of the physics.

> Because of this, I believe that vertical antennas near the earth ar
> doomed to mediocre performance at very low radiation angles (at HF).
> This is not to say that they make poor antennas.  They are capable of
> generating very strong skywave signals at angles of 15 to 45 degrees
> (depending on length and ground system) and this will grab you lots of
> good DX.

> However, it is awfully hard to beat a horizontal dipole if is way off
> the ground.  This is why most of the big gun SWBC stations use
> horizontally polarized curtain arrays.  Nothing like stacking a bunch of
> horizontal dipoles vertically to get you some gain sideways.  (c:

> Gray


> > Dear OM's

> > the question is not so easy to answer.
> > Over ideal ground, a ground mounted (insulated) half wave vertical is 1.7
> > dB over a ground mounted quarter wave. This is because in the case of the
> > half wave, the "upper" and "lower" part of the sineshape current
> > distribution add up in phase in some directions.
> > Over real ground, the situation is more complicated. If one wants to have
> > high gain into low elevation angles, one must use a very big radial
> > system. This is because the resultant field strength adds up from a direct
> > component and a component reflected from the ground. Over real ground,
> > this reflection is lossy and there is a phase shift. This is in connection
> > with the so called "pseudo-Brewster" angle. In optics, you observe, using
> > vertical polarized light, that, under some angle, there will be no
> > reflection from a horizontal oriented dielectric surface. This is the so
> > called Brewster angle, where the light enters completely the dielectric
> > medium. If the medium is lossy, all the light is absorbed. The same is
> > approximately true for radio waves, with the possible exception, that the
> > assumption of plane waves does not hold very close to the antenna.
> > The consequence of this Brewster effect is, that you have to improve the
> > conductivity of your ground very far away from the antenna. For example if
> > you want a high gain at 20 Degrees, you must provide a hgh conductive
> > surface at a distance of (lambda/4)/tan(20 Degress) approx 0.7 * lambda
> > away from the antenna, assuming that the current loop is at 1/4 lambda.
> > This is true for the vertical dipole and the base fed as well.

> > Vy 73

> > Ralf

> > DL 6 OAP

> --
> Telecommunications Engineering
> Gray Frierson Haertig & Assoc.
> 820 North River Street, Suite 100
> Portland, Oregon 97227
> 503-282-2989
> 503-282-3181  FAX


 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Richard Harris » Wed, 27 Oct 1999 04:00:00

Ralf, DL 6 OAP answered the question in the header: "This is true for
the vertical dipole and the base fed as well."

A wire doesn`t care how it is e***d. The same current in the same wire
produces the same pattern.

To solve stealth and mechanical problems, maybe we could aim a pencil
thin beam of ionizing radiation at the zenith. We might couple our h-f
energy to this conducting shaft by surrounfing it with a toroid e***d
from our transmitter.

Details yet to be developed.

Best regards, Richard Harrison, KB5WZI

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by W6RCecil » Wed, 27 Oct 1999 04:00:00


> Ralf, DL 6 OAP answered the question in the header: "This is true for
> the vertical dipole and the base fed as well."

> A wire doesn`t care how it is e***d. The same current in the same wire
> produces the same pattern.

> To solve stealth and mechanical problems, maybe we could aim a pencil
> thin beam of ionizing radiation at the zenith. We might couple our h-f
> energy to this conducting shaft by surrounfing it with a toroid e***d
> from our transmitter.

> Details yet to be developed.

Seems Star Wars' Laser Swords should be ionizing. The latest Star Wars
even has dipoles. :-)
--
73, Cecil, W6RCA   http://www.redwaveradio.com/~w6rca
 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by pot » Wed, 27 Oct 1999 04:00:00

Better???   Worse???  They have different lobe patterns.. In the real world
the 1/2 wave above ground has superior performance as compared against the
"ground plane".  Remember the dipole has a gain of unity (iso) and the gain
of a ground plane is 0.8......
Now a true 1/2 wave end feed vertical has a "High" input imp
therefore it is not as dependent for a "good" ground as the "high voltage
produced overcomes the "high ground restistance......Of course extra
attention MUST be paid on the decoupling of the feedline in non-ground plane
ants.

Cary Vond


> Question:
> Is a 1/2-wave vertical over real ground better or worse than a 1/2-wave
> dipole just above real ground?

> The ARRL Antenna Book has patterns for perfect earth. We know that the
> horizontal dipole would produce a doughnut of radiation around the
> center of the wire were it not for the presence of the ground. The
> ground`s proximity tends to cancel ground-level energy because
> reflection from the ground is out of phase for the horizontal wire. A
> horizontal dipole near the ground is mostly a cloud warmer. Between 1/4
> and 1/2 wavelength elevation above ground the 1/2-wave dipole produces
> radiation at useful angles for communications of several hundred to
> maybe a thousand miles. Your mileage may vary. Lossy ground reduces the
> radiation amplitude and distinction in the pattern shapes.

> The ground reflection of a ground mounted vertical 1/2-wave antenna is
> in phase with the radiator. Excellent low-angle radiation results. But,
> the 30-degree elevation radiation is much less than that produced from
> the horizontal dipole at 1/2-wave elevation. So, if you want to talk 200
> to 700 miles, more or less, the horizontal 1/2-wave may be a better
> antenna for you. For DX, the vertical 1/2-wave with a good ground system
> would be hard to beat.

> Best regards, Richard Harrison, KB5WZI

 
 
 

Half Wave Vertical vs. Half Wave vertical Dipole??

Post by Chipn1 » Thu, 28 Oct 1999 04:00:00

Quote:>>I'm with KC6UFE...and would add that  a  full  half wave "radiator"  is
>>something like  1.5 db stronger in field intensity  than a quarter wave
>>"radiator".

>It IS?

>> This is  due to a full current "loop"  on it  versus only a half
>>a current loop  on the shorter one.

>That is incorrect. According to this logic,  an 1/8 wave, lossless dipole is
>3
>dB below a 1/2 wave lossless dipole.

>According to this logic, an infinitesimal losslessloop has zero dBi, when in
>fact is has 1.8 dBi.

>This is very wrong.

>Also,  over a large GP a 1/2 wave vertical has MORE than a
>full "current loop".

>> Funny,  It is the same old story...Field
>>intensity  is proportional to the current flowing......73  "DM"

>No; field strength depends on the current distribution and ohmic loss.

>The question, as posed, is: a 1/2 wave VERTICAL over real ground better or
>worse than a 1/2 wave DIPOLE just above real ground?

>The answer to this is not obvious; if no one else gets back to you, I'll
>model
>the two and tell you in a couple of days when I can free up a few minutes. My
>speculation is that the 1/2 wave vertical, with a good radial system, over
>real
>ground, has the higher f.s.

>73
>Chip n1IR

With 32 radials, the 1/2 wave vertical has about 0.25 dB more gain than a
vertical half wave dipole over real (good) ground, with radials up about a foot
at 14 MHz.

Essentially they are the same.

73,
Chip n1IR