Antenna 9:1 impedance transformer for the RTL-SDR to connect long wire 100k - 50Mhz (BALUN)
NEW 1PC9:1 HF BALUN for Beverage antenna Long wire antenna RTL SDR Software radio receiver (software defined radio)|Earphone Accessories| - AliExpress
Amateur radio long wire HF dipole antenna and balun fixed to the side of a house wall Stock Photo - Alamy
Magnetic Long Wire Antenna Matcher (9:1) for SWL, 100 KHz-30 MHz - Antenna Products - Palomar Engineers®
Amazon.com: Balun One Nine v1 - Tiny Low-Cost 1:9 HF Antenna Balun and Unun with Antenna Input Protection for Ham It Up, RTL-SDR, HackRF and Other HF-Capable Radios. Great for DIY Dipole