Longwire antenna help needed!

[OttawaSWL]

I'm a shortwave listener - interested mostly in hams and broadcasters below 30MHz. My receiver is an RSP2Pro (software-defined receiver). I have erected a U-shaped, end-fed longwire antenna - total length about 75 feet, all segments of the U are approximately equal in length. (I chose this configuration because of the space I have to work with). It is about 30 feet above the ground. The antenna feeds into a "matchbox" with a 9:1 transformer. The matchbox outputs through about 10 feet of coax to the high-impedence port of the receiver.

I occasionally listen to VHF/UHF on the RSP2Pro using a simple, car-top scanner antenna. Today, as an experiment while listening to HF, I switched over from the longwire to the VHF/UHF antenna. To my surprise and disappointment, there was virtually no difference in signal strength or quality vs. the longwire. How could this be? What is wrong with my longwire antenna? What can I do to improve it?

Thanks!

 

[prcguy]

Your wire antenna with 9:1 transformer is a low impedance antenna. Try connecting it to a 50 ohm or low impedance input on the receiver.
prcguy

 

[WA8ZTZ]

Your wire antenna with 9:1 transformer is a low impedance antenna. Try connecting it to a 50 ohm or low impedance input on the receiver.
prcguy

^^^ this

Also, you don't mention what HF station you were listening to but some HF broadcast stations can be received S9+++ to the point of overloading the RX even using just a coat hanger for an antenna. Thus, you may notice very little difference between a whip and a longwire on a very strong signal.

Experimenting with antennas is all part of the radio experience fun.