5 el. 50 Ohms U-YAGI HPSD

[Henry HPSD]

Hi guys,

For the DXers :

A 5el on a rouglhy 7 meter boom producing over 10 dBI and
over 30 dB front to back ...OVERALL...
That combined with a 50 ohm direct impedance (split dipole)
Makes it very very hard to beat...

This is just version 1.01 though im confident its probarbly the best out there on such a boom. The pattern is just amazing..

The origin lies more or less in the hands of mr LA moxon (sk) and UA9TC.
The have done tremendous effort in "optimizing" yagi's by bending the elements.

This is the first for 11 meter.
I havnt thougth of a "commercial" name yet...though i am thinking of putting them in production.

Anyway...all the dimensions are there...so good luck constructing what is todays TOP!

If you need other dimensions...let me know...ill see what i can do (not promissing anything bussy hihi).

Kind Regards,

Henry

 

[Robb]

The polar plots of the F-Yagi and the U-Yagi look similar - if not the same.

So; is the total length of the Moxon-like reflector of the U-Yagi the same as a standard Yagi?

The spacing of the reflector/radiator/1st director are so close together on the U-Yagi compared to a standard Yagi - too . . .

 

[Henry HPSD]

Hello Rob,

The patterns indeed are similar but not all the same.
Needless to say the F-yagi is the one to beat

The biggest "striking" difference being how the antenna achieves its 50 ohms impedance.

The F-Yagi has a folded dipole (with all the benefits provided
(Closed loop, if needed: dc grounded, less P-static etc.)

Now, the "frame" of the antenna (f-yagi) is a 12,5 ohm yagi beam,
Where the folded dipole transforms this to 50 ohms without any matching loss.
It is already known that traditional "low impedance" yagi's have more gain/FB etc.
Sadly no one was able to make it a "wide band" yagi until a couple years ago.
In my opinion people like DK7ZB have done the first steps in this direction.
And we are just pushing it more to the limit.

The UA9TC type is rather "strange" in this concept.
By bending and optimizing the reflector the impedance rises without the need of a folded dipole.
As mentioned...it is a split driven element, making it easier to construct from a "home builders point of view".

But more importantly...it shows where people "thought" we have touched the edges of the antenna beam design world.....it shows were not there yet !

It is clear to me: the fun has just started.

Attached is a pdf file where the two are "compared".

The F-yagi has slightly more gain, but the U-Yagi has a better "overall" pattern.
Please take a close look at the back of the antenna...it is tight.
Besides the back the elevation plot of the U-yagi is "tight".
This can be a benefit living in a "city" environment, the "local" QRM will be reduced.

Finally...
As mentioned the fun has just started.

I honestly believe both "types" can probably be improved (combining them perhaps?)
But are already exceeding what is available today (maco/jogunn/sirio/wolf etc)

Some "expert" expectation lies with "modern" yagi's to have more "bends"
(If you look at the moxon's provided on All about antennas some have really good specifications.)
Providing perhaps slightly more gain, as also my believe is gain is already pushed to the limit (give or take a couple tens) but more importantly a beam who is more "tight".
Has a 50 ohms impedance and remains high over a wide frequency region.
That is probarbly the challenge for the future.

Kind regards,

Henry Poelman
19SD348
All about antennas
HPSD Antenna systems

 

[Henry HPSD]

Me again,

almost forgot to answer a couple of your questions:

1- Yes the reflector length is more or less similair compared to a traditional yagi.
2- In aspect to element spacing:
No, there are "many" traditional yagi's who will show similair or less element spacing.
A 5el "owa" yagi on a 16/17 foot boom is a famous one for example.
The F-yagi has real tigth (back) element spacing. As thats the one who "gets away"
with it due to lower impedance.

Perhaps you already knew, but otherwise ...my compliments !
You mentioned the first three elements (ref/rad/dir1)
Some people call them the "impedance cell". As they are primarily responsible for it.

Regards, H.

All about antennas
HPSD Antenna systems

 

[The Hitman]

IS HPSD HENRY STILL TRADING?

 

[Alexis Mercado]

Me again,

almost forgot to answer a couple of your questions:

1- Yes the reflector length is more or less similair compared to a traditional yagi.
2- In aspect to element spacing:
No, there are "many" traditional yagi's who will show similair or less element spacing.
A 5el "owa" yagi on a 16/17 foot boom is a famous one for example.
The F-yagi has real tigth (back) element spacing. As thats the one who "gets away"
with it due to lower impedance.

Perhaps you already knew, but otherwise ...my compliments !
You mentioned the first three elements (ref/rad/dir1)
Some people call them the "impedance cell". As they are primarily responsible for it.

Regards, H.

All about antennas
HPSD Antenna systems

Interesting

 

[AudioShockwav]

Try sending Henry a private message.
I do see the two sites down, hope he is ok.

73
Jeff

 

[Henry HPSD]

Apologize, a bit late for an answer...

No, i dont trade ...
but i do have the www.cb-antennas.com information website back online !

Kind regards,
H.