Eliminate mismatching & future proof your transmission lines
If you’ve always used 50 ohm connectors on 75 ohm cable with few if any problems then why should you change the habit of a lifetime?
Well, for a start you might want to consider that mismatched BNC terminations can seriously degrade the capabilities of high performance cables.
Sure, at lower frequencies (below 300MHz) little difference in electrical performance can be detected but with the expansion of digital transmission, and with ever increasing bit rates, future proofing transmission lines by eliminating mismatching becomes even more of a priority.
And with Coax Connectors’ new plug, cable jack and jack-to-jack adaptors promising optimisation to 75 ohm throughout the connector length of the majority of 75 ohm cables, there really is no excuse to continue with a mix & match approach.
Available in two frequency bands, the higher (HD6 Range) for high performance video cable incorporates indent crimp technology for the centre contact termination. This method maintains a more uniform electrical length to achieve higher return loss results as shown in chart 1.
The second series (HD3 Range) incorporates industry standard hexagonal and square crimping but still maintains return loss figures (chart 1.) suitable for most commercial applications.
Both connector ranges have been optimised to 75 ohms for each cable style throughout the complete connector length. This has been achieved with a combination of air and ptfe dielectric with consideration to the complete connector length.
Worryingly, in the course of development it was found that many connectors sold on the open market under the 75 ohm banner have only had the interface modified, and are in fact closer to 60 than 75 ohm!
The performance of the HD6 range shows frequency and impedance measurements resulting in return loss measurements (with Belden 1505A cable) of typically better than 30dB at 1GHz, and 27dB at 3GHz (shown as red trace). Time domain measurements show a smooth 75ohm impedance transition throughout the connector.
The HD3 range is designed for more commercial applications and typically performs at 29dB at 2GHz but is cable dependant.
The importance of the centre contact mechanical crimp termination in relation to plating, base material and base material hardness was also found to be crucial in terms of achieving optimum performance.
Many centre contacts in connectors currently available exhibited spring back (relating to material hardness) after crimping which could result in high resistance joints over time.