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4 element yagi specs

3

33 the kid

Member
Mar 12, 2006
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hey all im putting my 4element back up after tower crashed got a crank up now i was wondering if anybody has specs to improve my m104. i seen the 4element on sognal engineering page but its set up to talk above the normal 40channels i only talk on the regular 40 letme know
thanks 33
 

Just run it with the way it was built. The Maco has a longer beam length than the optimized Yagi you saw on that page. Better to have a longer beam than the shortened one that page offers/shows.

Just make sure the elements are snug on their mounting hubs and the elements and are as parallel as possible. Maco's tend to be a bit sloppy in that fit. Tune the Gamma match with the beam on the ground laying on its reflector and pointing straight up into the air. I adjusted my beam that way after I was told to do it that way. That was usable and verified info, and it really was easier to tune using that method. After I mounted it, I re-checked it and it was solid. Now; that is a hot tip for ya!

You might want to consider using the element spacings from the Henry HPSD page. Probably a bit better than the dimensions than the Maco's use - BTW. The dimensions are all in metric, but you can get a calculator online to change them to US measurement standards. This page will give dimensions for either a long boom or a short boom element spacing. Longer is better; nothing wrong with a short boom if that is what you have. I use a short boom Yagi and had many xlnt results - BTW . . .

Here's Henry HPSD's page:
http://www.dx-antennas.com/Yagi4.htm
 
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Singal engineering:
Signal_Engineering_4element_Yagi

Maco 4 elements:
MACO_104C

I know that wasnt what you were looking for, hihi....but now you know what the antennas do.

I have tried a couple runs, but time lacked my end.
Ill give it more time, but that will probarbly not be before next week.
Upto now it seems the gain is about max and if one improves the FB the gain dropes and vica versa...it migth be we cant get it "much" better than the maco figures provided with just the 4 elements as they are.

Just a short question...

Would you be willing to add another element beneath the radiator ?

So the radiator becomes a folded dipole ?
Similair to this : 11-4 F-YAGI – HPSD Antenna systems

I can get about 9,4 dBI from that boomlength (compared to the 8,4/8.7 from the maco and signal engineering) and a higher FB and a straigth 50 ohms impedance.

You would need to isolate the top part of the radiating element..

Just wondering...

Kind regards,

Henry
 
Last edited:
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hi henry, i would be interested if you have a diagram and specs, i have extra elements and more boom soo i can do it does it still use a gamma, or does it use hairpin since its isolated?
thanks scot 33
 
Hello,

Actually...

The higher gain and FB numbers are already reached with slightly less boomlength compared to the Maco/Sig. eng.

The antenna is a direct fed 50 ohms.
No gamma-match or other matching device is needed.
So there is no loss there (how small that migth be)
However a RFchoke 4/5 turns RG213 10cm diamter or a 1:1 balun is adviced.

Since it is a loop configuration, some say it has less noise due to that fact.
Which they sometimes claim for the quad aswell.

And power is limited to the element diameter instead of the matching device.
thats a lot higher than a couple Kw's hihi.

It is also known that low impedance yagi's are critical to rain/snow/buildings.
High impedance yagi's (like the F-yagi) are less critical.
Some migth recognize when the rain comes up the noise floor runs up..
This antenna reduces that.

Not only the azimuth point is remarkable...but also the elevation plot.
That helps reducing "city" noises.

So what you need to do:

Place 1 element below the radiating element.
Cut the "original" radiating element in the middel.
Isolate that "original" radiating element.

You can leave the other part of the radiating element "dc-grounded" to the boom.
(thats another advantage..this antenna can truly be "dc-grounded".)

At the end of both elements you need to connect both to each other.
Attached is a picture how i do it.

What i will need to know from you...is the distance between the two elements.

Kind regards,

Henry 19SD348

Edit:
I actually prefer isolating everything.(each element)
The reason for this:
Most manufacturers use steel U bolts to secure the element to the aluminium element plate.
That uses steel U bolts to be attached to the aluminium boom.

If you carefully calculate antennas you need to calculate it with boom.
On 11 meter its not a real big issue but on higher bands it is.
There is a word for it... Boom-correction (in short BC)
Since steel and aluminium dont combine the electrical connection become less when corrosion (time) steps in.
Which will cause a change in the antenna pattern.
(that also goes by the way for not calculating hairpin matches within the design etc)
Anyway if all elements are isolated there is no influence...and you dont need to bare in mind the boom thingy. The pattern will always be the same.
 

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Hey Henry, since it's a magnetic loop, would a 1:1 balun even be necessary?


Sent from my iPhone using Tapatalk
 
Hi 359,

Its not a magnetic loop. Its a fullsize loop. A magnetic loop antenna would be much smaller in size.

And there are many other ways of matching a sleeve would be nice aswell.

And no, none of them (RF choke/1:1 balun etc) is really needed...
But can help in some situations.
How often these situations happen....well...not frequently.
Just take a look at most beam antennas around..you dont see a gamma-match and a 1:1 balun that often do you hihi.

Kind regards

Henry
HPSD Antenna systems
All about antennas
 
that was my next ? element lengths and spacing. i have some fiberglass tubing to make driven element isolated. u must adjust reflect by element length ? then shield of coax to one side and hot to other of isolated element?
 
@ Homer BB,
Where did you see the loop was shorter than a dipole driven element would be ?
They are more or less equal.

You can only determine these antennas using a NEC4 modeling engine.
NEC2 (as with the "basis" eznec) is inaccurate with loops.
Sadly Nec4 is for commercial uses is quite expensive.

@33
I asked you to determine the distance between the top element and bottum element of the radiating element. Could you give me that spacing ?

Your question: you must adjust reflect by element length >?.. Im not sure if i understand correct. IF you are wondering how to adjust the antenna....
Well if you are "spot on" with the dimensions you wont need to "tune" anything.
Thats the beauty of it. All already is optimized.
Changing the element length will indeed change resonant frequency (and impedance etc)

Kind regards,

Henry Poelman
 
Henry HPSD said:
@ Homer BB,
Where did you see the loop was shorter than a dipole driven element would be ?
They are more or less equal.

You can only determine these antennas using a NEC4 modeling engine.
NEC2 (as with the "basis" eznec) is inaccurate with loops.
Sadly Nec4 is for commercial uses is quite expensive.



Kind regards,

Henry Poelman
Click to expand...

In these photos it looked shorter than the first director.
Perhaps it is an illusion. . .

29et013-1.jpg


I can't afford Nec4, and if I had it do not know how to use it . . . Yep, sad.
 

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