Quad vs Yagi (or log)
 

Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
Yagi, I should be curious to know your opinion about both designs, pro and
cons in various conditions of work (installed on the roof, 10m away fro the
hosue, 2m high only, etc).

I need for example some more information about the noise generated by a yagi
vs a quad or any other relevant information at which I don't think about.
For example, at first "sight" the quad generates 5-10 dB less than a quad.
Have you some similar information or other with all relevant data (nbr of
elements of concerned antennas, wind speed during measurements, location of
antenna, etc).

Also, I am interested in the drawbacks of each model (quad, yagi, log). I
discuss about this problem too, but I 'd like to go further in this matter.
The question is : why did you choose - or didn't choose - this design
(another reason than its price with is of course the main factor).

Thanks in advance

Thierry
ON4SKY

Sorry guys, I mixed 2 problems related to noise.
There are first the noise generated by beam vs quad, but I cannot estimate
the noise level, excepting that the quad is more silent under high wind.

The 5-10 dB less for the quad are related to the white noise. I explain.
According a swedish OM, it appears also some kind of white electrical noise
on a beam compared to a quad. The theory/argument is that the Yagi is more
prone to picking it up due to its high impedance at the dipole ends.

Quoted and translated from Swedish:
"The noise I talk about is on eg. 20 m and 5-10dB above the threshold on a
yagi but barely audible on a quad. It has always the same strength
independent of the time of day, possibly a bit weaker at sunrise. The noise
from static discharges are completely different. The noise I am talking
about is more "white"."
Quoting the list: "I have performed tests between Yagi/quad specailly on 20
meters. I have used a 5 el monoband yagi and a 6 el monoband quad. The
difference is about 5-10dB. The direction seems to be irrelevant, the white
noise is everywhere. "

The origin of noise is unclear but thoughts are (and these are
speculations): Perhaps the first skip of NVIS-noise from a town nearby? Or
that the quad's liftoff angle is different that the yagi's and so picks up
anything from another angle?

Can someone confirm this better performing of the quad ?

Thanks
Thierry
ON4SKY

"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
...

Bill Turner wrote:

SNIP

And finally, don't be persuaded by that old saying about how a two
element quad is equal to a three element yagi. So what? A three
element yagi is FAR easier to build than a two element quad.

The bottom line is this: Once the quad is up in the air, it will
generally outperform a yagi of equivalent cost. The problems lie in
getting it up in the air and keeping it there.

If I had it all to do over again, starting from scratch, I probably
would use a yagi.

--
73, Bill W6WRT
QSLs via LoTW

And, I would use a Log Periodic!! I give up about 1 dB in gain and
acquire a 13.5 MHz to 33 MHz broadband antenna, no traps, full legal
power handling capability and a VSWR 2:1 across the full range. That
means 20, 17, 15, 12 and 10 meters all in ONE Beam.

W1MCE

I have a few thoughts.
I used a 3 / 3 Yagi for 10 years.

I currently have a 5 band 2 element Quad, one feedline to a switch box on
the boom, then series sections to match.

I chose the quad to minimize turning radius. My Yagi hung over the fence
line to the neighbor, the quad does not.

The verticle size is a challenge.

My local tower ordinance is 35 feet to the top of the structure. The top
of the quad is the top of the structure.

I had the tower inspected before I put up the quad.

Standing on my Garage roof I can adjust the 20 meter elements.

An effect that I notice, that I did not have with the Yagi, is that the
tuning changes based on the direction that the
quad is pointed. I attribute this to the proximity to the aluminum sided
garage, and a couple of trees.

Visual impact has not been an issue. It is shorter than the trees, which is
probably why I have not had any city trouble with the
hieght of the top of the quad.


"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
Yagi, I should be curious to know your opinion about both designs, pro and
cons in various conditions of work (installed on the roof, 10m away fro
the
hosue, 2m high only, etc).

I need for example some more information about the noise generated by a
yagi
vs a quad or any other relevant information at which I don't think about.
For example, at first "sight" the quad generates 5-10 dB less than a quad.
Have you some similar information or other with all relevant data (nbr of
elements of concerned antennas, wind speed during measurements, location
of
antenna, etc).

Also, I am interested in the drawbacks of each model (quad, yagi, log). I
discuss about this problem too, but I 'd like to go further in this
matter.
The question is : why did you choose - or didn't choose - this design
(another reason than its price with is of course the main factor).

Thanks in advance

Thierry
ON4SKY

Quad advantages:

1. Simple. Only wires and coax. No baluns, traps, gammas, hairpins,
etc. Full legal power continuously with no problems.

A yagi can be made with a direct dipole feed, which is very simple. BOTH
the quad and yagi need a balun.

2. Broadband. Covers 20/15/10 with less than 2:1 SWR, even on 10.

See Cebik's studies of quads (www.cebik.com). Quads give a very
narrow front/back bandwidth. Not enough even to cover most amateur
bands with = 20 dB F/B.

3. Light. For a given level of performance, a quad should be a bit
lighter than a yagi.

True for a 2 element quad (boomless), but not with more elements. Look
at some of the weights at http://www.mgs4u.com/catalog/.

Torsten
N4OGW

What's a, "narrow front/back bandwidth"?
'Doc

What's a, "narrow front/back bandwidth"?

The pattern (usually quantified by font/back ratio) only remains good over
a narrow frequency range.

Torsten
N4OGW

"KA9CAR" wrote in message
...

....

My local tower ordinance is 35 feet to the top of the structure. The
top
of the quad is the top of the structure.

I had the tower inspected before I put up the quad.

So, your tower is 35 feet tall, right? Good...
__
Steve
KI5YG
..

Hi Bill,

In article ,
says...


On 12 Feb 2004 12:39:06 -0600, (R. Torsten
Clay) wrote:

A yagi can be made with a direct dipole feed, which is very simple.

Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

It all depends how you tune the yagi. For example,
a two-element yagi with about 0.2 wavelength spacing,
with a reflector approximately 5% longer than the
driven element will offer a very good match to
50 ohm coax (according to EZNEC). Costs only a few
tenths of a dB in forward gain to get that match.

73,
Bob
K3PH

--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+

A yagi can be made with a direct dipole feed, which is very simple.

__________________________________________________ _______

Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

See for example

http://www.cebik.com/a10/ant35.html
http://www.naic.edu/~angel/kp4ao/ham/owa.html

just depends on how you tune the yagi. Give up a little (0.5 dB?) gain,
and the impedance can be 50 ohms.

Torsten
N4OGW

A yagi can be made with a direct dipole feed, which is very simple.


Please explain how. All the yagis I've heard of have a very low
feedpoint impedance. How do you use 50 ohm coax without a matching
device of some kind?

One approach can be seen at:

http://www.clarc.org/Articles/uhf.htm

This method, by Kent Britain WA5VJB, uses a combination of a
half-folded driven element, and a proper selection of element spacing,
to allow the direct connection of 50-ohm coax. They don't provide the
highest gain or F/B ratio possible with a Yagi, but it sounds as if
the sacrifice in gain is modest.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

In article ,
says...

On Fri, 13 Feb 2004 10:41:01 -0500, Bob Schreibmaier
wrote:
It all depends how you tune the yagi. For example,
a two-element yagi with about 0.2 wavelength spacing,
with a reflector approximately 5% longer than the
driven element will offer a very good match to
50-ohm coax (according to EZNEC). Costs only a few
tenths of a dB in forward gain to get that match.
_________________________________________________ ________

Ok, maybe so, but a two-element yagi is a waste of time in my book. If
you're going to that much trouble to build one, add a third element and
get a little more pizzaz.

Perhaps, but this, too, may be tuned for a very good
match to 50-ohm coax at only a small sacrifice in
forward gain. You are probably aware that Force 12
does exactly this. And, of course, the Mosley TA-series
tribanders that have been on the market for some 45
years have direct 50-ohm feed with a very good match.

73,
Bob
K3PH

--
+----------------------------------------------+
| Bob Schreibmaier K3PH | E-mail: |
| Kresgeville, PA 18333 | http://www.dxis.org |
+----------------------------------------------+

It depends on what one wishes to accomplish and how long one expects the
antenna to endure.
It is assumed that the antenna is designed to survive the pressure
due to the expected peak wind velocity (at the height where it is
mounted) and expected radial ice loading. [See EIA 222F or G]
For near maximum performance on a single band (or set of single
bands) with a tower that is at least one wavelength high, a yagi with at
least three elements is hard to beat - especially if one mounts
additional antennas on the same rotating mast.

For about 1 to 2 db less than what can be achieved with a (single
band) yagi, and perhaps that much more than many triband beams, - on a
tower that is at least one wavelength high at the lowest frequency - one
may cover all of the HF bands from 14 MHz up with one LPDA (log
periodic). In my opinion, on the higher HF bands, most radio amateurs
will be best served with a LPDA in view of the span of frequencies now
available and the lack of a need to tweak well designed examples of such
antennas.
73 Mac N8TT

--
J. Mc Laughlin - Michigan USA

"Dave Shrader" wrote in
snip

And, I would use a Log Periodic!! I give up about 1 dB in gain and
acquire a 13.5 MHz to 33 MHz broadband antenna, no traps, full legal
power handling capability and a VSWR 2:1 across the full range. That
means 20, 17, 15, 12 and 10 meters all in ONE Beam.

W1MCE

Bill Turner wrote:

On Sat, 14 Feb 2004 16:35:21 -0500, "J. McLaughlin"
wrote:


For about 1 to 2 db less than what can be achieved with a (single
band) yagi,

snip

Hard core DXers will commit mayhem for one dB and will kill for two.
That's why they don't use LPDA's.

Hard core DXers have their Long Johns tuned to 14.025 MHz and won't work
more than 25 KHz from that frequency!

If you read the beginning of this post it refers to 'many hams'.

If you want maximum gain on one frequency, or sub-band, then I agree
that a Long John tuned to your favorite frequency is the way to go. But,
if you want good to very good performance across the whole HF spectrum
from 13.5 to 33 MHz, or higher, in ONE antenna then the ONLY choice,
IMO, is a LPDA.

There is a solid reason why the governments of the world use LPDAs for
State Department, FAA and Defense HF communications.

If you want maximum gain on one frequency, or sub-band, then I agree
that a Long John tuned to your favorite frequency is the way to go. But,
if you want good to very good performance across the whole HF spectrum
from 13.5 to 33 MHz, or higher, in ONE antenna then the ONLY choice,
IMO, is a LPDA.

There is a solid reason why the governments of the world use LPDAs for
State Department, FAA and Defense HF communications.




Aaaah, not so fast.
Have you checked StepIR tunable antennas with monobander performance on any
frequency within that band? Plus instant pattern flip and much less cumbersome
than LP. Read comments from users. This antenna is making LPs obsolete (unless
you need spread spectrum instant coverage)

Yuri, K3BU.

Their web page is at
http://www.steppir.com/
they have range of beams and verticals that are tunable accross the range. On
beams they do not change element spacing, but there is enough range to
maintaing good pattern and gain. Many users love them, they are weather
resistant. The idea is that they use metallic tape inside of fiberglass tubing
and motion is done by stepping motors, which are very reliable.

They are tunable to particular frequencies, so they are not "broadband" like LP
arrays, but they beat LP in performance on any frequency withing the range.

73 Yuri


I find your comment very interesting. I was totally unaware that the
IR
antenna had laterally moveable elements so it can compete with
monobanders.
Can you point me to a URL that shows how the elements are moved along
the boom?
I suspect that such a design would provide spread spectrum coverage
since it would be resonant on all frequencies.

Regards
Art

Howdy,

The thing I have noticed in my travels is that most of the quad antennas I've
seen are CB antennas.

And many of them are damaged presumeably by the wind. I seem to see the wires
"blowin' in the wind".

It's hard to beat a Yagi for gain, performance, durability, weight, cost,
ability to match, etc.

73, Jack K9CUN

It's hard to beat a Yagi for gain, performance, durability, weight, cost,
ability to match, etc.

73, Jack K9CUN



Properly designed and built Quad will beat Yagi in all the above mentioned
"parameters". Little more cumbersome to raise on a tower with guy wires, but
easily doable.

Yuri, K3BU.us

Yuri, K3BU wrote:
"Properly designed and built Quad will beat Yagi in all the Above
mentioned "parameters"."

The author of "All About Cubical Quad Antennas", Bill Orr, W6SAI says:
"The power of the 3-element or 2-element Yagi, however, is not swept
aside by the Monster Quad, no matter what the size and power gain of
this impressive antenna."

Orr says measurements with an accuracy of a decibel or better are hard
to believe. His table shows about 1.7 dB advantage for a Quad with 2 or
3 elements over the Yagi, and the boom length may be about 2/3 that of
the Yagi, he says the reason for building a Quad instead of a Yagi is
likely a matter of opinion as to the value of the small edge the Quad
may have versus the extra cost and effort to get the Quad up.

Orr says he used both the Yagi and the Quad for years as did many of his
good friends. He says objective and subjective tests show the Quad has a
definite advantage in terms of signal strength over the Yagi antenna.

Best regards, Richard Harrison, KB5WZI

Richard Harrison wrote:
Orr says he used both the Yagi and the Quad for years as did many of his
good friends. He says objective and subjective tests show the Quad has a
definite advantage in terms of signal strength over the Yagi antenna.

It is good to remember that the Quad was invented to solve a particular
problem.

From Orr's book concerning the 4-element Yagi initially installed:

"Totally unexpected, however, was the effect of operating the high-Q
(Yagi) beam antenna in the thin evening air of Quinto. Situated at 10,000
feet altitude in the Andes, the beam antenna reacted in a strange way to
the mountain atmosphere. Gigantic corona discharges sprang full-blown from
the tips of the driven element and directors, standing out in mid-air
and burning with a wicked hiss and crackle. The heavy industrial aluminum
tubing used for the elements of the doomed beam glowed with the heat of the
arc and turned incandescent at the tips. Large molten chunks of aluminum
dropped to the ground as the inexorable fire slowly consumed the antenna."

"The corona discharges were so loud and so intense that they could be seen
and heard singing and burning a quarter-mile away from the station. The
music and programs of HCJB could be clearly heard through the quite night
air of the city as the r-f energy gave fuel to the crowns of fire clinging
to the tips of the antenna elements."

C. Moore invented the Quad beam to solve that somewhat special problem.

Quads also have all the advantages that loops enjoy over dipoles. One
thing that comes to mind is a marked reduction in static electricity due
to wind and snow because the entire loop is virtually at DC ground.
--
73, Cecil http://www.qsl.net/w5dxp



-----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
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Quads also have all the advantages that loops enjoy over dipoles. One
thing that comes to mind is a marked reduction in static electricity due
to wind and snow because the entire loop is virtually at DC ground.

A yagi built with "plumbers delight" construction has every element bolted
directly to the metal boom, so every element is at DC ground.

Torsten
N4OGW

Quads also have all the advantages that loops enjoy over dipoles. One
thing that comes to mind is a marked reduction in static electricity due
to wind and snow because the entire loop is virtually at DC ground.
--
73, Cecil http://www.qsl.net/w5dxp



That's what I thought too, I built the quads using insulated wire in hope to
eliminate atmospheric static, but I could barely tell the difference. What made
huge difference (wiping out static completely) is the use of stacked antennas,
or having larger antenna over the one in use. The top one would be 20 over S9
while lower one is dead silent.

Quad advantages: made of wire, no corroded junctions like with Al tubing. Quads
rule up to about 5 el. then Yagis take over. I have 3 el. design that is 50
ohms, no matching, broad band. One advantage quad has that it is only antenna
that can be used for different polarizations with the same hardware. Parasitic
loop doesn't know what polarization it is.

Yuri, K3BU.us

When I compared my requirements against what a yagi versus a quad would
deliver, there was no contest - a quad met my needs better than a yagi. I
purchased a Gem boomless (spider) quad for the following reasons:
- lightweight (small rotor)
- small footprint (9 foot turning radius)
- all bands including WARC from 6 - 20 meters
- optimally spaced elements for each band
- individually tune each band without interaction
- good performance, quiet receive
- no magic (traps)... I can build it, tune it, fix it
- relatively inexpensive

Notice that my requirements do not include the best gain figures nor the
best F/B ratio --- which I think you will only get with a monoband
no-compromise yagi. Unfortunately, yagis don't meet my other requirements.

-larry
K8UT
"Thierry" To answer me in private use
http://www.astrosurf.com/lombry/post.htm wrote in message
...
Hi,

Before investing in a future antenna I have discussed on my site about
antennas designs, quad vs yagi or log.
http://www.astrosurf.com/lombry/antenna4.htm
I would like to get more information from users. If you used both quad and
Yagi, I should be curious to know your opinion about both designs, pro and
cons in various conditions of work (installed on the roof, 10m away fro
the
hosue, 2m high only, etc).

I need for example some more information about the noise generated by a
yagi
vs a quad or any other relevant information at which I don't think about.
For example, at first "sight" the quad generates 5-10 dB less than a quad.
Have you some similar information or other with all relevant data (nbr of
elements of concerned antennas, wind speed during measurements, location
of
antenna, etc).

Also, I am interested in the drawbacks of each model (quad, yagi, log). I
discuss about this problem too, but I 'd like to go further in this
matter.
The question is : why did you choose - or didn't choose - this design
(another reason than its price with is of course the main factor).

Thanks in advance

Thierry
ON4SKY