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.

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.

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.

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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

·        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!

The list of oblongs >>>>

© Boban YU7XL