When several antennas must operate on the same platform, selecting components that individually meet their specifications is not enough.

The real challenge is understanding how the antennas will behave together once they are installed in the actual configuration.

Modern RF systems integrate an increasing number of antennas, frequency bands and radio equipment within spaces that are often severely constrained. Transmitting and receiving antennas must coexist with metal structures, radomes, cables, onboard electronics and mechanical elements that may alter their behaviour.

Under these conditions, antennas that have been correctly designed and characterized as individual components may interact with one another and exhibit different radiation patterns and performance after installation.

The risk is discovering only during system integration or final testing that the antenna subsystem does not operate as expected.

When these problems emerge too late, additional testing, mechanical modifications, redesign activities or the replacement of components that have already been manufactured may become necessary. This can increase costs, extend development times and affect the entire project.

ElettroMagnetic Services S.r.l. designs custom multi-antenna systems and integrated antenna subsystems, treating the complete configuration as a coherent system rather than a simple combination of independent antennas.

Why Antennas Cannot Be Evaluated Separately

Why Antennas Cannot Be Evaluated Separately

Each antenna may meet its individual requirements when tested in isolation and behave differently after integration into the final platform.

Other antennas, metal surfaces, radomes, cables, electronic equipment and supporting structures may affect impedance matching, gain, radiation patterns, polarization, isolation between RF ports and the effective coverage of the system.

Compliance of the individual components therefore does not automatically guarantee the correct operation of the complete system.

Evaluating the performance of each antenna separately is not sufficient. The overall behaviour of the antenna system must be assessed in the actual configuration intended for the application.

RF Isolation and Coexistence Between Antennas

RF Isolation and Coexistence Between Antennas

When transmitting and receiving antennas operate simultaneously on the same platform, isolation between the different RF channels becomes a fundamental requirement.

Excessive coupling may transfer energy from one antenna to another, increase interference levels, reduce receiver sensitivity or compromise the simultaneous operation of the connected equipment.

The resulting interaction depends on several factors, including:

• operating frequency bands;

• transmitted power levels;

• distance and relative orientation between antennas;

• antenna polarization;

• radiation patterns;

• installation positions;

• surrounding metal structures;

• the electromagnetic characteristics of the complete platform.

There is therefore no universally applicable minimum separation distance between antennas.

Two antennas that appear to be sufficiently far apart may still provide inadequate isolation. Conversely, a more compact configuration may operate effectively when frequencies, polarizations and the overall geometry are considered during the design process.

RF coexistence must consequently be evaluated for the specific configuration rather than through general rules applied independently of the platform.

Interaction with Radomes and Platform Structures

Interaction with Radomes and Platform Structures

The performance of a multi-antenna system also depends on the physical environment in which the antennas are installed.

Radomes, metal surfaces, panels, brackets, masts, cabins, enclosures, shelters, superstructures, cables and electronic equipment can alter electromagnetic behaviour compared with measurements performed on isolated antennas.

A radiation pattern that is suitable under ideal test conditions may exhibit distortion, attenuation or coverage gaps after installation.

Even a radome developed primarily as a mechanical or environmental protection can influence the radiation characteristics of the antennas installed inside it.

Separating antenna design from antenna integration may therefore result in components that perform correctly in isolation but are not suitable for the final platform.

The antenna system must be evaluated by considering RF performance, geometry, materials, installation positions and surrounding structures at the same time.

Multi-Antenna Systems in Space-Constrained Platforms

Multi-Antenna Systems in Space-Constrained Platforms

Special-purpose vehicles, naval platforms, drones, unmanned systems, shelters, towers and transportable equipment frequently impose demanding constraints in terms of available space, weight and geometry.

Within the same platform, it may be necessary to integrate several RF functions, including:

• professional communications;

• data links;

• telemetry;

• GNSS;

• RF detection;

• direction finding;

• spectrum monitoring;

• radar;

• identification and localization systems.

The need to accommodate all antennas within the available space may result in configurations where antenna positions are determined primarily by mechanical constraints rather than RF performance.

The problem becomes even more critical as the number of antennas increases, operating bands become closer or overlap, and several RF devices must operate simultaneously.

Under these conditions, adapting separately selected antennas after the platform has already been designed may not be sufficient.

A custom multi-antenna configuration may be required, developed from the outset according to both the RF objectives and the physical constraints of the platform.

When to Consider Custom Multi-Antenna System Design

When to Consider Custom Multi-Antenna System Design

An integrated approach should be considered whenever multiple antennas must operate on the same platform, particularly when transmitting and receiving equipment is active simultaneously, the available installation space is limited or surrounding structures may alter antenna behaviour.

Custom multi-antenna system design becomes especially important when the project requires:

• several RF functions within the same radome or mechanical volume;

• defined isolation levels between antenna ports;

• simultaneous operation of multiple radio systems;

• control of interference and unwanted coupling;

• consistent performance after installation;

• specific radiation coverage from the complete platform;

• integration into a mechanically complex structure.

Addressing these aspects during the early stages of development makes it possible to assess the compatibility between RF requirements and the physical configuration before design choices become difficult or expensive to modify.

The Risks of Addressing Integration Too Late

The Risks of Addressing Integration Too Late

When the mechanical development of the platform and the selection of antennas proceed independently, integration problems may emerge only after the first prototypes have been manufactured.

At that stage, it may be necessary to change antenna positions, modify radomes or supporting structures, replace previously selected components, revise cable routing and repeat measurements and characterization activities.

In other cases, corrective measures may need to be introduced, performance compromises accepted or system validation and industrialization delayed.

The space required for an alternative configuration may also no longer be available.

Considering the antenna subsystem from the beginning of the project makes it possible to identify the main incompatibilities in advance and reduce the risk that RF integration becomes the weak point of the complete platform.

One Integrated Subsystem, Not a Collection of Components

One Integrated Subsystem, Not a Collection of Components

Within a multi-antenna system, the position, orientation and characteristics of each antenna can influence the behaviour of all the others.

It is therefore not always possible to optimize every antenna separately and subsequently combine the resulting components.

The design process must identify the most appropriate overall balance between:

• individual antenna performance;

• isolation between RF ports;

• radiation coverage;

• dimensions and weight;

• mechanical and environmental robustness;

• radome characteristics;

• interfaces with the final platform.

The objective is not necessarily to maximize one individual parameter under isolated conditions. It is to develop an antenna subsystem that reflects the operational priorities of the application as a whole.

Applications for Custom Multi-Antenna Systems

Applications for Custom Multi-Antenna Systems

RF integration and coexistence are particularly important in:

• defence and security systems;

• Counter-UAS and counter-drone systems;

• radar and remote-sensing applications;

• naval and marine platforms;

• special-purpose vehicles;

• UAV, UGV, ROV and other unmanned platforms;

• avionics;

• professional telecommunications;

• telecontrol and remote-monitoring systems.

In these applications, several RF functions often need to coexist within limited spaces, close to complex structures and under operating conditions where system reliability is essential.

Our Technical Scope

Our Technical Scope

ElettroMagnetic Services S.r.l. specializes in the design, integration, prototyping, manufacturing and characterization of custom multi-antenna systems.

Our technical scope covers the antenna subsystem and may include:

• individual antenna elements;

• integrated or combined antenna configurations;

• radomes;

• mounting and supporting systems;

• mechanical interfaces;

• elements required for electromagnetic integration into the Customer’s platform.

We do not supply active RF electronics, firmware or communication equipment.

We design the antenna subsystem so that it can operate correctly with the Customer’s RF equipment and within the intended platform configuration.

Let’s Discuss Your Multi-Antenna Project

Let’s Discuss Your Multi-Antenna Project

Are you developing a platform that integrates several antennas, frequency bands or RF systems?

Are you uncertain about coexistence between different RF functions, or have you already encountered isolation, interference, coupling or installed-performance problems during integration?

We can examine the configuration, system requirements and main constraints of your platform together.

An initial technical assessment can help determine whether the antennas can be managed as independent components or whether the project should be approached as one integrated multi-antenna subsystem.

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