Mobile Antenna

[df9rb]

Hi all,

I built a mobile antenna with 1 m wire, vertical mounted on the roof of my car on a magnetic holder. Directily at the feedpoint a 1:9 impedance transformer is installed and short coaxial cable to the DRT1 receiver. The complete equipment has no DC connection to my car only the holder is capacitve coupled to the car.
(laptop powered by the accumulator, the DRT1 via USB from the laptop). The results are surpisingly!
- no noise from the car
tests at around 9:30 local time (7:30 UTC)
- below 1 MHz signals are weak (i. e. 177 kHz SNR 8 dB)
- 1296 and 1440 up to 20 dB SNR
- AM from Radio Vatican on 1611 audible
- all stations up to 15780 MHz with good signals

The log in the attachment shows a short drive from top
of a mountain (520 m above sea level) back home (rural area to city)

Bernd, DF9RB

[FritzWue]

Hi Bernd,

mediumwave works with your transformer too.
What material and shape do you use for the 9:1 transformer?

[df9rb]

Hi Fritz,

material is unknown - perhaps I would need more windings - or the as the antenna is only 1/1500 wavelength long for 177 kHz an amplifier with high input impedance is a must.
At the moment I use 6/18 windings.

Bernd, DF9RB