Colin's Antennas

a computer analysis by 1839


After Colin's message I ran some computer simulation based on his projects. The software is Eznec by W7EL. I selected medium quality ground.

The results quite confirm Colin's observation.

The first antenna is a horizontal dipole at 5m. Although the antenna have some gain, 6.66 dBi, the high takeoff angle, 31 degree, let it not a good performer for dx. Just an example of how gain, without more specifications, can be deceptive.

The second antenna, a vertical dipole with his centre at 6m, has a lot low gain, 1.47 dBi, but also lower takeoff. So the dx performances are not so different, with maybe a little advantage for the vertical one at very low angles. And the vertical one should be more advantaged by exceptionally good ground, if any.

Here the two plots.



The third antenna, "V" dipole, is high at 7m. That's why it's a better dx performer. The max gain is 7.07 dbi at 20 degree, with 4.44 dBi at 10 degree. Here his pattern superimposed to the horizontal at 5m.



But what if we put the horizontal dipole at 7m? Surprise, the conventional dipole should be a little better than 'V' ;-)



Now the last antenna, the lazy one. Yes, that have F/B, about 4dB. But the result of crossed polarisation is a reduced gain, at least for takeoff angle over 5 degree. Btw because one 'S' point should be 6 dB, is not so easy to judge antennas by signal report...



Sorry, I ran those on the fly, if someone can add something or have suggestions, please drop me a line ;-)