V-Star Antenna
Here you will find information about our V-Star antenna, which is excellent for transmitting and receiving from 1MHz to 32MHz. It is constructed from design instructions by Karl Rothammel.
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The antenna we use in our station is the so-called V-Star. Which theoretically is published in the antennas manual by Karl Rothammel. After long experiments we found that this is one very effective and easy to manufacture antenna. But an amateur must have about 8 acres of land, in order to be able to realize its construction.
The first experiment with this antenna we made with only three rods in 1992. We used it around 4-5 years, while working with power around 200W and we were quite pleased with the results obtained with it, both in reception and transmission.
Then we disassembled it and started to make a variety of structures, such as a pyramid for 3.5MHz, 4 slupers for 7MHz and other long wires and dipoles. Using the results from each of these antennas, we realised we made a mistake when we disassembled the V-star.
So we decided to get back to it, not only with its construction, but also with its effective tuning at the final stage. Rothammel published in his book only theoretical tuning device which can tune in the lines with two collins filters. For setting up we used the unit MFJ 249, and initially a small antenna tuner which is for a symmetric L type antenna. We chose the length of the antenna rods as published by Rothammel – 42 meters and 5 in count.
The result was a high SWR from 28MHz to 30MHz. For the 28.000 scope part the antenna is tuned in voltage, and the other part of 28.500 – in current. We did experiments with several variants of tuners for tuning of symmetrical antennas T and L, but received high SWR.
This is why we decided to try to make the antenna as proposed by DL7AB. At two meters from the power line we put the Notch coils with a diameter of 50 mm, five turns of 2mm wire. It was a striking effect, the antenna began to tune very well from 1.5MHz to 32MHz. We have tried various powers from 10W to 1kW. The antenna has a much greater effect especially of 1.8 and 3.5 and not to mention the higher ranges.
The height of the mast, which we used in the centre where the rods exit is 21.5 meters. The mast is made of duraluminum pipes of 120mm diameter. At the top, there are located 5 bars of fiberglass in a star formation, where the star diagonal is 4 meters, two meters from the end of the rods to the pipe itself.
We made a symmetric feed line from five conductors of stranded copper wire, two squares and a half. Studs between the lines are made of 1mm glass fibre of length of 100 mm and distance of 90 mm between the wires. The length of each of the five symmetrical feed lines is 23 meters.