RIG

On this page i want to describe my equipment which i am using at home and portable.

Some Remarks about the Antenna

As mentioned above, basically the antenna is a vertical antenna and the radials are on ground (neither elevated nor buried). This has the big advantage that there is no need to tune the length of the radials for each frequency - in contrast to a ground plane which requires precise tuining of the lengths or the radials. But the three radials are by far not enought. On the other hand: three are better than nothing. Since the antenna is 10 m tall, we have a quarter lambda for 40 m and a half wave antenna for 20m; the latter one can be considered to be a vertical dipole fed at its end. On 17 m the antenna come close to a 5/8-lambda having in general a main lobe at a low elevation angles. The low number of radials will increase that angle because of the non ideal ground. Unfortunately, it is difficult for an amateur to do simulations with radials on ground because the popular NEC2-kernel is not capable of doing such simulations. NEC2 requires elevated radials. NEC4, in contrast, can do similations even with buried radials but it is quite expensive - for amateur use too expensive. Considering the amateur radio bands 15 m and above, new lobes at high elevation angles become more and more effective and make the antenna not well suited for DX. Below 40 m the antenna is short compared to lambda/4. This has the well known consequence that the antenna impedance becomes smaller and smaller (far below 50 Ohm) and the losses of the nonideal ground become more and more prominent. A better ground network (more radials) at least would reduce the losses and thus increase the efficiency of the antenna. In addition on 80m and on 160 m the losses of the impedance matching network of the antenna coupler also contribute to the losses of the whole system even if the coupler transforms to 50 Ohm and the SWR is 1. But the SWR of a dummy load is also 1 and a dummy load is a quite bad antenna. Anyway, the situation is not too bad. It seems that a con work many of the stations, which i can read. Not all, but quite a lot of them. And this is more than i expected before havin set up this station.