Benelec LMR VHF and UHF Quarter Wave Stub EMP Lightning Surge Protector

The Benelec LMR VHF and UHF Quarter Wave Stub EMP Lightning Surge Protector, available with N-Type and 4.3-10 Socket options, helps to protect valuable radio equipment from lightning strikes and surges. It is designed to provide a wide range of benefits over traditional EMPs, employing a quarter-wavelength short circuit stub-based technology.

The short circuit at the end of the stub is transformed into an open circuit at the bottom. Thus, the RF on the main line is inessentially uninfluenced, and the stub acts like a simple band-pass filter with the quarter-wave frequency as centre frequency. The configuration is an N socket at one end and N socket bulkhead at the other end. This facilitates the integration of this EMP onto earthing plates and feed-through panels. It is supplied with an L bracket for cable tray mounting.

The UHF device covers the full 380–520 MHz band and the VHF version covers 136–174 MHz bands. Other options are available for Cellular 5G bands. The device is available in other connector types including 7–16 DIN variants.

Because of the galvanic connection of the inner and outer conductor, a DC transmission or pass is not possible. Other hybrid models will cater for the DC pass requirements.

Within the product the stub is folded into the axis of the main RF line, resulting in an ‘inline’ design. This means the diameter of the device is not much greater than the diameter of 7/8″ feeder cable, allowing use in high-density feeder installations.

The product offers several benefits for radio system designers and integrators. The design eliminates any non-linear component (eg, a gas discharge arrestor), resulting in good intermodulation figures (typically -165 dBc). No parts will deteriorate over time, meaning the EMP is a set-and-forget, maintenance-free device, eliminating visits to site due to EMPs failing over time. The device is also RF power-independent, working at all RF powers up to 800 W.