Summer 2020. DXpedition to Albania

This summer I had the vacations. As the year before. And before. Suddenly we realized that because of the coronavirus all countries were closed for Ukrainian citizens but Albania. This circumstance became crucial while looking for the country we'd like to rest in. And now I can say we are completely happy with our choice.

Because of CoViD-19, we were able to make the final decision only seven days before the flight. As far as I have a CEPT license I had no worries about the possibility to temporarily work from Albania without any additional license. And that was my huge mistake: in order to get explicit permission from the hotel management, I had to provide the Albanian license. That was the reason why I was not able to work from the hotel during the entire stay.

Shortened dipole. How to design one for 40 meters band.

Sometimes you don't have an opportunity to choose an antenna. You can be either limited in finances or space, but the only antenna you may build is something small. Just imagine you live in a country house and have two 10-meters-tall trees with a distance of 15 meters between them, leaving you only 11-12 meters of free space for your antenna. You want to be present on 40 meters band, where the propagation does live the whole day. Since you don't want to build a ground plane, you have chosen to build the dipole. Good choice: the dipole is a pretty good and easy to build antenna requiring not so many materials. But you have realized you have no space for this antenna: diagrams tell you that the antenna must be 20 meters long. So sad...

But, don't panic! A shortened dipole is your choice. Let's try to design the shortened dipole that could fit the space between your trees!

Shortened dipole. How does it work?

Recently I was asked about the shortened dipole. In a nutshell: the question was pretty simple - is this possible to create a small yet effective antenna for 80 meters band. Below is a result of my thoughts on this topic as well as some number of diagrams, which, as everybody knows, worse one thousand words.

Let's start from basics: the antenna is a wire conducting the RF current. As far as we are talking not about the conducting of the DC, the basic understanding of the RF transmission is a must, although this is out of the scope of this article.

How the height affects the antenna

After the third article, I decided to perform more general work and calculate the same antenna on the different height. In a nutshell, the antenna parameters depend on the height the antenna is placed at. I stored some number of pictures, looking at which worse thousands of words.

The antenna is a quarter-wave GP with two radials. I know that the number of radials does matter, but this is very quick, thus not very thorough exercise. The antenna is made of aluminum pipe (R=10 mm, 3/8 inches), counterpoises are an aluminum wire (R=0.8 mm). The antenna was designed to be mounted on the 1 meter (3 feet) tall mast.

HF 70 watts power amplifier DIY kit. Part 1.

Some time ago I ĥave bought a DIY kit - the 70 watts HF power amplifier. The reason for buying is simple: I have a low power transceiver (20 watts) and sometimes it is required to make it stronger to reach more distant stations not being able to hear my quiet voice. And although 70 watts is not dramatically bigger than 20, I decided to buy it - the price is reasonable and the overall complexity of joining all together is pretty low.