I got this long wire antenna outside 20 feet above ground and an AM broadcast filter and can hear strong ham stations on 80 m and 40 m but not successful with shortwave broadcast stations here in the noisy suburbs of Phoenix.
Might work better out in the desert.
Is it by any chance one of these? If so, I've noticed the same thing. Just touching the connector can reduce a lot of the noise. I wonder what I can do to make a more reliable ground.
Usmile® LW1650 Portable Long Line... https://www.amazon.com/dp/B0141X3B5W?ref=ppx_pop_mob_ap_share
If you want to sniff around the entire frequency range the SDR is capable of receiving you will want something outdoors and as high as you can get it. Just stick a long wire in the center hole of the SMA connector and run it up a tree. Attaching a 15-20 foot wire to the outside of the SMA connector as a counterpoise might lower the noise floor a little.
When you're ready for a better setup, you'll still want it outdoors and high but you will also want to do a better job of matching the impedance of the SDR; something like this: https://www.amazon.com/dp/B0141X3B5W/ref=cm_sw_r_cp_dp_T1_z8DEzbKNJ7ZMH