For: 11 meter band DX section

Antenna Type:    3el  Quagi

“THE SKYREX “

Designed by:    HPSD version 1.01 May 2014

Based on original work from Alex 9AT119 (EX-1sd019)

Boom length: 3,45 Meter
Gain: 8,80 dBI (@27,555 Mhz)
FB: >27 dB
FR: >18 dB
Impedance: 50 ohms, direct fed
SWR below 1:1.1> 50 Khz.
SWR below 2:1 > 450 Khz

Above the freespace azimuth plot.

Above the freespace elevation plot.

Above the 2:1 SWR bandwidth

Above the elevation plot when the antenna is placed at 18 meters heigth above average ground conditions.

Above gain versus frequency.

Above front to back versus frequency

Above front to rear versus frequency

ELEMENT DIAMETER

Each element is made out of copper wire with a 1,5 mm diameter
bare in mind,this is not the same as 1,5mm2 black electrical
house wire.

DO NOT CHANGE ELEMENT DIAMETERS OR INDIVIDUAL SECTION LENGTHS.  

 ELEMENT DISTANCES

Reflector - radiator :    1,30 Meter and 1,40 Meter. 
The top and bottom of the loop are sligth bend forward.
Reflector - director 1 :  3,45 Meter

ELEMENT LENGTHS:

Reflector: 5,30 Meter
Radiator:  2,784 Meter ALL 4 parts. Loop heigth = 2,4 meter total
(1,2 Meter above and below boom)
and the length loop is 5,02 Meter wide.
Director 1: 5,03 Meter

FEEDING THE ANTENNA:

The antenna has 50 ohms impedance. It can be "direct" fed.
All you need to do is split the radiating element in half, 
isolate it from the boom and attach the coax on it.
Of course a RF choke / 1:1 balun is advised.

Any futher questions please feel free to use the forum (top bar)

____________________________________________________________________

 SOME SIDE NOTES ON THIS ANTENNA:

For a while now, I was really impressed with the skyrex designed
by Mr Alex 1SD019. Although the concept isnt new...(a quagi) 
We dont see them often on 11 meters.
After having asked Alex, he said it was no problem to "upload"
The dimensions we optimised...tnx Alex !

Playing around with this antenna and optimising the loop sizes,
we came to some interesting conclusions:

Although this antenna has a relative narrow SWR bandwidth, the 
antenna is ideal for the DX portion of our CB band 
(27,4-27,7 MHz). The rather narrow bandwidth is very common 
for a 3el cubical quad. In this case it is still wide enough 
to be of use.

So what is so nice about this antenna ? 
A remarkable feature is the tigth pattern.
Infact one could consider this antenna to be a "low noise" 
version.

The term low noise, has been used more commen with the 
introduction of the LFA antenna by Justin G0KSC. In short 
if the antenna pattern is tigth the antenna temperature 
will improve. Although that factor is of less interest 
on 27 MHz, it still is nice to have a tigth elevation pattern. 
As you will have less qrm from electrical devices 
(house equipment laptop etc).

So let us compare the Skyrex with a 3el LFA:

We see the Skyrex has sligth more gain 
(8,6 versus 8,8 dBI)
We also notice the LFA has one rather large backwards lob.
SO in front to back the Skyrex is on top as well.

When we compare the elevation pattern: we can notice that the 
SKYREX, is overall more "tigth".. providing less noise.

Above a plot, when both antennas are situated at 18 meter above 
ground. We can see the back of the skyrex remains "closed".
In this case the lobs pointing backwards between 0-45 degrees 
are in favour of the skyrex, (smaller) 
reducing the qrm comming from the back of the antenna.

Now, im not saying the LFA is a bad antenna, heck no..
Its a great antenna for sure. But I am saying: in this case
the skyrex has some features which migth be more benneficial.

Not a bad antenna !