This is a super portable passive HF/VHF loop antenna designed for super low / receivers like the Airspy HF+ Discovery. It also works to some extent with the RTL-SDR V3 in direct sampling mode if you enable RTL AGC. But for radios without super low specs, the signals can be boosted on by using any external low cost HF amplifier, or even our wideband LNA.The YouLoop design is based on the Mbius loop idea where a balanced electric shield is used as the center of a multi-turn loop. The rest of the turns run inside the shield. This construction is electrically balanced for wave wavelengths, ie.when Lambda is very compared to the size of the antenna. This helps cancelling the electric noise at the lower bands, exactly where most of the electric noise energy is concentrated. To preserve this electric balance from alteration by the transmission line, a low loss miniature BALUN is used.Therefore this is NOT a resonant antenna, hence the requirements for very low radios or an amplifier.Specification:HF Response: 10kHz to 30 MHzVHF Response: up to 300 MHzMaximum : 250 mWFeedline Length: 6m (SMA male to male)Features:Passive designNo tuning requiredLow-loss wide-band BALUN with 0.28 dB loss typ.Colour: blue + white + blackMaterial: ABS + metalSize: 60 x 36 x 20mmPackage Contents:1 x T-shaped BALUN1 x phase inverter2 x 1m RG402 coaxial cable1 x 6m RG174 coaxial feederNote: This antenna is designed for portable use and is not weatherproof. Permanent mounting can be achieved with weatherproofing tape.Only the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.