Hi!
Thank you for reading this.
Antennas are my obsession. In my ham
career I have built and tried several hundreds of different antenna
types, for HF, VHF, UHF...but, I started designing seriously when I
got familiar with some antenna modeling software, which I received
from YU7EF, a good friend of mine, who has already been famous for
his good, low temperature yagi models.
Here you can see my own models.
Mostly, they are not yagis, but oblongs. Looking at the diagrams,
you will find these antennas very interesting
I have found that rectangle can be a
better antenna than yagi. All performances achieved are better,
including gain, unwanted lobes suppression, bigger bandwidth, lower
temperature, and finally, their G/T ratio is dramatically better!
Especially on UHF.
The main thing with oblongs is that
they are insensitive to the influence of surrounding condition and
to the constructing errors. For example, if the yagi element
diameter is changed from 5 to 5, 5 millimeters, this antenna becomes
for waste. On the other hand, if you change the oblong elements from
5 to 10 millime-ters, and this change is made systematically on all
elements, such an antenna is still useful. Therefore, any boom
correction is not necessary.
![](my_oblong_models_files/image002.jpg)
Oblong antenna
Q209E3XL (built by YU7XL)
I suggest that elements are mounted
isolated, over the boom. Placing over the boom gives two favours:
- Less coupling
between elements and boom, and
- When stacked,
you can save on the length of supporting frames.
If placed so, it would be necessary
(for 144 MHz only) to connect upper sides of elements with a piece
of solid plastic pipe, to prevent them from oscillating on wind.
![](my_oblong_models_files/image004.jpg)
Holder of element made
of polyester car repair kit (YU7XL)
The picture shows one of possible
solutions how to make element holders using polyester car repair
kit. The wire ends are joined by welding or by wire terminals and
covered with polyester in this way that wires inside polyester
cannot move. Another, fast solution is proposed by YU1QT, meaning
that wire ends are joined by wire terminal and then terminal plastic
body is fixed on a squared boom with screws The last solution is not
recommended if you want the antenna to last long time.
.
Radiator holder made on a piece of
polyester laminate (YU7XL)
Radiator holder can be made on a piece
of PCB laminate, as shown on the picture. After checking the
antenna, the holder, together with element wires and coax cable, can
be covered with polyester coat, so that its junctions are protected
from oxidation.
Someone could say oblong is not easy
to build. Try to build and get proven this is not true. Of course,
more element material is required, but every extra centimeter of
element length is worth of money spent.
Though I have made many oblong models,
I have to prepare them to be published here. Therefore, this web
site will permanently be under reconstruction, so I will add new
models, one by one.
I have built one of my models only:
Q209E3XL Immidiately after raising it up, the antenna gave the same
performances as achieved on my computer screen.
It was shown that coaxial cable can be
connected to the radiator directly, with no balun, without a visible
destruction in the antenna radiation pattern.
All models are free for ham building
purpose. The only thing I request is your response. Please, send to
me your photos and comments, because just a few models have already
been proven in praxis, and I need references how they behave on
mast. Thank you in advance!
This way, I want to
thank YU7EF and YU1QT for their support and comments.
Some additional
explanations:
·
Designation: I am using the designation principle that the first
letter stands for the type of antenna. The next character is a
number standing for the band. The following two numbers shows the
number of elements. The letter after that shows the height of
element (as given in the table), and the number is just a serial
number, followed by XL (YU7XL).
DESIGNATION OF YU7XL ANTENNAS
TYPE OF ANTENNA |
HEIGHT OF ELEMENTS (for 144 MHz
only) |
K |
QUAGIES |
A |
Up to 200
mm |
Q |
OBLONGS |
B |
200 250
mm |
Y |
YAGIS |
C |
250 300
mm |
X |
DOUBLE BOOM
YAGIS |
D |
300 350
mm |
W |
DOUBLE BOOM
QUAGIS |
E |
350 400
mm |
R |
COLINEAR
ARRAYS |
F |
400 450
mm |
|
|
G |
450 500
mm |
|
|
H |
Over than
500 mm |
·
All my
antennas are 50 Ohms fed, except additionaly marked
·
Comparison: wherever possible I have given the basic performances od
corresponding YU7EF yagi antenna for comparison purpose, so that you
can see the typical difference between yagis and oblongs.
·
SWR
pattern is given in two ways: for SWR=1,5, and for ham band
144,000-146,000 kHz.
·
Radiation patterns are given separately for NO-LOSS and
LOSS-included condition.
·
Befora
entering into antenna files, you can firstly take a look on the list
of all exposed antennas, with shor descriptions, put in order of
boomlength, so that you can easily make your choice.
·
Antennas
marked with QQ... stand for double element oblongs, as shown on the
following picture. They are fed in the central horizontal wire.
·
Enjoy!
![](my_oblong_models_files/image008.jpg)
The list
of oblongs >>>>
© Boban YU7XL
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