Mk11 – Boosting OPV capabilities

Combining radar and IFF

Smaller vessels used by navies and coast guards – including offshore patrol vessels (OPVs) – are often limited in space above and below deck, reducing the number of sensors that can be installed. To address this market in particular, HENSOLDT UK has pioneered a combined radar and Identification Friend or Foe (IFF) solution that maximises the limited mast space available on-board small vessels while increasing overall capability.

October 11, 2021

Sea, Radar, IFF, SharpEye

Status Quo – Missing space for IFF

For OPVs and similar sized ships used by navies, coastguards and border agencies, an integrated sensor suite normally includes an electro-optical system for visual identification and recognition, and a radar for navigation and situational awareness.  But there is little room left for more powerful sensors that are found on larger warships, such as IFF.

“Typically on a warship, an Identification Friend or Foe system will have an entirely separate antenna and turning unit, which is a problem for smaller vessels because the mast space is very limited and there could be interference with other sensors as it emits,” explained Paul Linfield, Regional Sales Director at HENSOLDT UK.

With this status quo in mind, HENSOLDT UK – which has set the standard in solid-state radar technology for a number of years with its flagship SharpEye radars – has come up with a novel solution that means even small vessels can integrate a powerful IFF capability. The company has developed a larger Mk11 turning unit that integrates an X-band SharpEye radar along with an IFF interrogator antenna.

The importance of IFF technologies

IFF technologies can accurately track a large number of targets and are vital when it comes to distinguishing between friendly and enemy forces. This is crucial for contemporary operations where allies from many different nations work closely together, and particularly when it comes to decreasing the chances of accidental “blue-on-blue” engagements, also known as friendly fire.


“Having an IFF capability means that crews can identify an unknown object or target and determine whether it is friendly or not before they take action. So it’s pretty important that you get it right. This also includes encryption technology to make sure that an enemy cannot pretend to be a friend.”

Paul Linfield
Regional Sales Director HENSOLDT UK

There are two main components in an IFF system, the interrogator (a high power, large antenna) that sends out an interrogation message to a target and prompts a response to ensure it is friendly, and the transponder (a smaller antenna), which can pick up an interrogation message from another platform and also respond.


Flexible IFF integrations depending on requirements

An agnostic approach to the new Mk11 Radar/IFF design means that customers can choose an IFF solution that fits their requirements and budget. While many OPVs and similar vessels will normally be involved in relatively benign operations such as border and exclusive economic zone (EEZ) protection and security, some navies still require the latest advanced NATO Mode 5 IFF solution – which HENSOLDT is a leading provider of.

This advanced IFF is used on HENSOLDT’s multi-mode air surveillance and target acquisition radars, and can now be integrated onto the Mk11 to ensure interoperability with higher-end NATO naval capabilities such as frigates and destroyers.

If NATO Mode 5 is not a requirement, customers can also choose from a number of alternative solutions also produced by HENSOLDT.

What does this mean in terms of capability?

To begin with, a turning unit that combines both an IFF antenna and solid-state radar means that deck space is used as efficiently as possible, and weight and maintenance requirements are also reduced with the use of only one structure for two sensors.  

The Mk11 SharpEye turning unit also uses composite carbon fibre materials to save even more weight and can be installed with just three bolts with all radar electronics upmast. Being a direct drive unit with no gearbox, it makes it very easy to install and virtually maintenance free.

Having both sensors co-located on the same turning unit also reduces the possibilities that the signals from the IFF and radar will interfere with each other, with both emitting in the opposite direction from each other. “There is no interference to worry about” noted Linfield.

Tracking organic UAS on board vessels

In addition to identifying friendly or potentially hostile air targets, IFF technologies are also commonly used for air traffic control and tracking large numbers of aircraft. This use of IFF is important for vessel crews as more navies utilise unmanned aerial systems (UAS) onboard vessels to aid with long-range situational awareness and wide-area surveillance.

New vessels are being designed to accommodate UAS, including vertical take-off and landing (VTOL) variants that can be used on a small deck such as those found on OPVs.

An example of this is the French Navy’s new Patrouilleur d’Outre-Mer (POM) offshore patrol vessels, which will utilise HENSOLDT UK’s combined radar/IFF solution and will embark VTOL UAS. NEXEYA – a HENSOLDT company - will also supply the combat management system for these vessels.

Crews can use the IFF system for tracking and range clearance when operating the UAV, ensuring safety for any other manned aircraft that may be in the vicinity and allowing the UAV to be used beyond-line-of-sight for longer-range operations.

A long heritage in innovative maritime sensor solutions

The Mk11 SharpEye pulse Doppler radar provides significantly improved capabilities over commercially available solid-state navigation radars, including situational awareness in all weather conditions and in high sea states. This has now been supplied to over 30 navies and coast guards around the world, which is a testament to its performance and quality.

The addition of IFF technology onto the Mk11 takes this technology to the next level and provides an unprecedented capability to crews when it comes to situational awareness and long-range surveillance. HENSOLDT UK has a long legacy of sensor development and the new Mk11 Radar/IFF is a sign that it will remain at the forefront of maritime sensor technologies for the foreseeable future.