A receiving antenna for shortwave: The Mini-Whip
The mini whip antenna presented here is a particularly small but powerful active receiving antenna. It is based on a widespread construction proposal, whereby I used transistors that happened to be present here. Deviating from the usual building instructions with a copper-clad surface as antenna conductor, I used a shortened radiator of a VHF / UHF magnetic base antenna, which ends at the base with an M3 internal thread and can therefore be easily mounted with an M3 screw. So the antenna rightly bears the name "Mini-Whip", it is now actually a whip antenna again. It also opens up the possibility of experimenting with different conductor lengths. It is hardly surprising that different lengths are cheap depending on the receiving frequency.
I built the electronic circuit on a 5.08mm breadboard with soldering points according to the wiring diagram below. For the power supply, I use a small CB radio supply device with an output voltage of about 13,8 Volts. The operating voltage should not be chosen much lower in the interests of signal compatibility respectively a good intermodulation distance.
The antenna works very well if it is placed outside of electrical interference fields. Proximity to EDP systems, switching power supplies, LED lamps, dimmers and other interference fields must be avoided in any case. If possible, it is best to place the antenna outside of the apartment, for example in the garden at some distance from the house.