- 16 SWG conductors about 115mm apart has an impedance of about 600Ω; often built using spacers – open wire line
- Twin (Window) line is available in impedances of 300 and 450Ω – ladder line
- 75Ω twin balanced line with conductors embedded in polyethylene is also available – twin feeder
- Balanced line may be unbalanced by proximity to metal or earthed objects