Modern field radio technology demonstrates new prospects for HF radio communication through Ukrainian war observations

Modern warfare has used the Ukraine conflict (2022–2025) to demonstrate the harsh realities of current combat operations. Communication systems maintain their status as one of the most important domains, experiencing both ongoing transformation and escalating vulnerability, while also demonstrating resilience. Media coverage mostly focuses on drones and satellite systems, while HF (High Frequency) radios need evaluation, as these traditional tools continue to develop. 

The war experience has demonstrated that HF radios face challenges, yet their unique capabilities maintain their importance for specific operational needs. 

Traditional military communication tools maintain their position, as HF radios experience a modern resurgence. 

HF radio’s traditional role and “renaissance”

For multiple decades, HF radios have proven themselves to be reliable military communication devices, enabling beyond-line-of-sight (BLOS) connectivity without infrastructure dependence. The ionospheric reflection of their signals enables HF radios to establish communication networks that reach distances up to hundreds or even thousands of kilometres. Throughout history, HF radios have proven essential for military command and control systems, while also serving to transmit intelligence and supporting special operations forces. 

The term “HF Renaissance” has gained popularity in modern times. The development of adversary capabilities to destroy satellite systems, alongside other sophisticated communication networks, drives the current HF Renaissance. The operational environment benefits from HF radio independence and EW resistance, which makes it highly valuable.

History of HF communications

Lessons from the Ukrainian battlefields

The Ukraine conflict demonstrates both the strengths and weaknesses of HF radio operations through several key instances:

1. The price of being unprotected: History reveals that Russian forces employed unsecured HF channels together with civilian radios in their opening war operations. The lack of encryption allowed enemy forces to intercept crucial military communications, including operational commands and reports about unit difficulties. The secure and disciplined use of the communication device stands as an essential factor for success, regardless of the device’s capabilities.
2. The dilemma of detectability: One of the major difficulties associated with HF radios involves their ability to be detected. The powerful transmitters and large antennas that enhance communication distance simultaneously provide enemy signals intelligence with information about the sender’s position. Ukrainian military forces exercise extreme caution when using HF radios at their command centres, as they aim to avoid attracting enemy fire.
3. The need for reliable BLOS data: Modern warfare increasingly requires data transmission – situational awareness pictures, target information, logistics data. Voice communication alone is not sufficient. The high data rates of satellite systems, which Ukraine extensively uses, demonstrate the need for backup BLOS data communication links. 
4. VHF/UHF and SATCOM alongside: By implementing Western-supplied encrypted VHF/UHF tactical radios and satellite connections, Ukrainian forces have managed successful data transmission. HF radios function as secondary communication tools, replacing other options when primary data transmission methods become inaccessible. 

The contemporary battlefield demands HF solutions that combine reliability with long-distance reach, enhanced security features, reduced detection capabilities, and dual-mode voice and data transmission capabilities. 

KNL CNHF Manpack: An answer to wartime experiences

KNL developed the CNHF (Cognitive Networked High Frequency) Manpack field radio to tackle the issues that became evident during the Ukraine war. The following sections analyse how its features match the war-related learning outcomes:

• Security and encryption: The early stages of the war in Ukraine demonstrated how unprotected communication channels pose a significant threat to operations. Security stands as the primary focus of the KNL’s CNHF system. Modern military radios must implement standards-based encryption for both voice and data communications, even though specific encryption techniques remain confidential. This requirement is an absolute necessity to protect message confidentiality. 

• Managing detectability (LPI/LPD): The Low Probability of Intercept/Detection (LPI/LPD) system in modern systems works to reduce transmission visibility. KNL’s CNHF technology employs burst transmission patterns alongside cognitive abilities that control frequency usage. The combination of optimised transmission power with short, burst transmission patterns helps to reduce exposure risk when compared to standard, continuously transmitting high-power HF radios. Mobile troops benefit from the ability to use antennas that are efficient, yet small and deployable quickly.

• Reliable data transmission over long distances: The CNHF system operates as a data transmission system in addition to its voice communication functionality. It enables IP-based data transmission across HF frequencies on a global scale. In this way, military units can share situational awareness, exchange short messages, and transfer files or narrowband video without relying on satellites or fixed infrastructure. The system fulfils the requirement to send information beyond voice messages across BLOS distances, providing an essential alternative for SATCOM. 

• Cognition and networking: The “Cognitive Networked” capability of the radio allows it to examine frequency environments before making dynamic adjustments. Through independent channel listening, the radio identifies and establishes the most suitable transmission paths, improving both network reliability and performance in high-density frequency environments typical of contested electronic battlefields. With its networked functionality, the system enables users to create adaptable communication networks with enhanced resilience

• Usability and mobility: The CNHF Manpack meets the requirements for mobile soldiers. The system features both lightweight construction and durable materials, combined with straightforward functionality that remains functional under demanding situations. A modern user interface, together with automated system functions, helps operators reduce workload and speed up link establishment procedures. 

The CNHF Manpack represents modern HF radio technology, delivering long-range voice and data communication with lower detection risks than conventional HF systems. It is an essential technology for developing defence strategies in conflicts where communication links are targeted through intense electronic warfare and other threats. 

The evolving role of HF radio

The ongoing war in Ukraine has exposed that no communication system is completely secure or foolproof. The future of military communications will rely on a multi-layered structure that unites various systems through the PACE principle (Primary, Alternate, Contingency, Emergency). 

HF radio systems continue to evolve to meet contemporary battlefield requirements, even though many still consider them outdated technology. The fundamental value of HF radio lies in its ability to establish infrastructure-free, worldwide beyond-line-of-sight (BLOS) voice and data connections. 

The combination of cognitive features, advanced waveforms, strong encryption, and improved LPI/LPD capabilities makes HF radio an essential component of a complete communication system that functions even during network outages. 

Author: Juha Lehto, Lt Col ret. / MEng, Key Account Manager at KNL 

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