Reply To: Newbie Antenna Question

[GremlinParticipant]

Hi,

just using a adapter or alligator clip will not work and result in poor signal!
the key-word here is Impedance. this can be imagined as somekind of “virtual resistance” for AC at a given frequeny.
the SMA inputs have a Imedance of 50 Ohm, so the antenna wire and the antenna itself should have the same Impedance. this will maximise the
power at the input.

a simple wire as antenna has a MUCH higher Impedance of 300 Ohms or more. so if you connect it to the 50 Ohm input it is somkinde of shorted and the voltage
at the input drops rapidly -> bad signal.
there are different solutions: you can build an wire antenna with the right impedance or use a Balun (which in simple words is a transformer)
many HAM operators have instructions for antennas on their homepages (GOOGLE!), ready-to-use Baluns can be purchased.

depending on the frequencies you want listen to, consider to buy a wide-band antenna (Discone). they will work good for frequencies from 50Mhz up to 1,5GHz.
for VLF and shortwave you should use a adapted antenna (wire with balun). as you are not transmitting there is no need to use the big HAM baluns. there are
small ones available (e.g. Amazon) for receiving only, making them cheap.
there are active antennas like the popular MLA-30+ Magnetic Loop (very cheap but, ehm, very cheap. there are better ones) or “Whip Antennas” (E-Field).
I’m using a Bonito BoniWhip for VLF, AM and Shortwave. This Antenna has to be set up on a Pole away from the House, otherwise there is a lot of noise.

my very first try out of the RSPduo was with a simple flower tying wire, as i had no other long wire. 12 meters under the roof connected directly to the Hi-Z Input of the Duo makes it receive HAM-Stations from ALL over the world.

good luck
Ralf