COJOT and Alaris Antennas to exhibit at DSEI Japan 15 – 17 March 2023

COJOT, together with sister company, Alaris Antennas will be showcasing their products and expertise at this year’s DSEI Japan.

Taking place 15-17 March 2023, the second edition of DSEI Japan will bring the global defence and security sector together with the entire Japanese and wider Asian defence community to innovate, partner and share knowledge under one roof across three days.

COJOT was founded in 1986 and is located in Espoo, Finland. The company has more than 35 years of experience in the design, development and manufacture of leading-edge VHF/UHF/SHF antenna products, serving defense, military and homeland security markets globally. The Company develops innovative antenna solutions, including omnidirectional, directive, adaptive and steerable beam antennas, to improve connectivity, coverage and competitiveness of radio frequency equipment which is deployed to save lives and protect property.

Alaris Antennas designs, manufactures and sells specialised broadband antennas as well as other related radio frequency products. Its products are used in the communication, frequency spectrum monitoring, electronic warfare and other specialised markets. Clients are located across the globe and are system integrators, frequency spectrum regulators and players in the homeland security space.

View some of COJOT’s products we will showcase this year:




Our High-Band counter-IED Antennas

Selecting the right antenna for the right application and integrating it correctly into a Radio Frequency (RF) system is imperative.

Particularly in Electronic Countermeasure (ECM Antenna) applications, where RF systems are used to prevent the detonation of Radio Controlled Improvised Explosive Devices (RCIED) it is vital to understand the technological characteristics of wideband antennas. As a leading provider of wideband antennas for manpack/handheld and vehicle applications we provide highly reliable and effective omnidirectional antenna solutions.

View some of our high-band counter-RCIED antennas here:






New Counter-UAS Antennas from COJOT

According to research conducted by Teal Group: “It is estimated that military UAS procurement spending will increase from the current worldwide level of almost $10.6 billion annually in 2021 to $13 billion in 2030, totalling $123.1 billion over the next ten years.”

At COJOT, we pride ourselves in delivering superior antennas that is purpose-built for our client’s needs.

Our new Counter-UAS antennas are the latest additions to our growing portfolio:

The DA36B is a high gain antenna that does not require a ground plane for proper operation.

Its ideal performance in the 3000 – 6000 MHz frequency range and compact size make it very well suited for applications like drone or communication jamming.


The DA4348B‘s is a high gain directive loop antenna. It’s ideal performance is in the 430 – 480 MHz frequency range makes it very well suited for Counter-UAS and communication jamming applications.

Our Counter RCIED VHF Antennas are ready for the digital battlefield

Selecting the right antenna for the right application and integrating it correctly into a Radio Frequency (RF) system is imperative. Particularly in Electronic Countermeasure (ECM Antenna) applications, where RF systems are used to prevent the detonation of Radio Controlled Improvised Explosive Devices (RCIED) it is vital to understand the technological characteristics of wideband antennas.

COJOT has the knowledge and expertise to match the highly demanding and changing military operational requirements in the digital battlefield with a broad range of field-proven mobile military antennas. Our counter-RCIED VHF antenna range is comprehensive and purpose-built.


View the antennas here:








Field-proven magnetic base Antennas with strong holding force

COJOT’s omnidirectional mag-mount antennas are the preferred choice for applications and circumstances where permanent installations are not possible and a rapid deployment and removal is preferred or even required.

We provide a wide range of antennas covering VHF, UHF, GSM, LTE, 5G, WiFi and other bands. Each antenna features a strong, rugged magnet base for temporary mounting on suitable magnetic surfaces such as a vehicle roof or engine hood. The mag-mount grips the car very well, even at high speeds, with a typical vertical holding force of 280N.


Magnetic Mount Accessories

Standard types of vehicle (NATO/US base flange) and portable antennas can be installed with our optionally available mag-mounts, allowing antennas to be used for a quick and easy temporary set-up, including retro-fitting, providing a cost effective solution to overcome restrictions with permanent installations.



This is our range of field-proven magnetic mount antennas and accessories:

WB25512W (25 – 512 MHz)

WB30108W (30-108 MHz)

WB30175W (30-175MHz)

WBCX512W (118-512MHz)

WB460W (420 – 6000 MHz)

WB525W (500-6000MHz)




COJOT beam steering antennas with support for dual-polarized MIMO 

COJOT supplies Switched Beam Antennas (SBAs) for different frequency bands with support for MIMO (multiple input multiple output) – featuring dual RF inputs/outputs that are connected to a different polarization of the radiator elements. MIMO is an essential requirement as modern Radio Systems are often relying on this to enhance the capacity or coverage of a radio network.

COJOT SBAs are currently in use at major global players in multiple applications – fielded to Tactical Communication networks both on land and at sea. These contain fixed Point-to-Multipoint as well as Mobile-Ad-Hoc-Networks (MANET). SBAs fit extremely well to these kind of adapting networks like MESH – where on top of higher layer routing, physical RF link routing can also be utilized.

2x2MIMO System

Spectrum monitoring and management are key factors in these kind of modern communication networks and with different beam modes and fast beam steering capabilities, COJOT SBAs provide an ideal solution for these – offering enhanced LPI/LPD resistance.

SBA Enhances LPI/LPD Resistance

Automatic and quick network setup and management 

In addition to superior performance features and enhancements, COJOT beam steering antennas can also improve and facilitate common basic routines in a wireless network. One such example is when you add a new node to a mobile network, it is often problematic and time-consuming to manually allocate the precise direction of the best signal with directional antennas. However, using a SBA in omni-mode, the new node can join the network immediately and the link can be optimized afterwards by searching for the strongest signal using the SBA’s narrow beam. Similarly, the wide beam mode provides faster scanning time. The possibility to utilize sharp beams within a frame rate over the 360-degree area opens many possibilities for network management and usage of advanced network routing protocols like OSPF (Open Shortest Path First).


Coming Soon

  • BAND L/III+ (1350-2700 MHz): SBA1327B-DP

Introducing New 4G/5G Antennas for Counter-RCIED/Jamming Applications

COJOT introduces new wideband antennas that have been designed to meet the challenging requirements of mobile Counter-RCIED/Jamming applications for mobile networks.

In addition to high power handling capabilities and a rugged mechanical design, these new portable and vehicle antennas provide enhanced omnidirectional radiation performance to cover 4G / 5G frequencies.

View the new range:


  • Wideband dipole antenna
  • 690-3000MHz
  • 50W power rating


  • High gain dipole antenna
  • 690-3000MHz
  • Up to 75W power rating


  • High gain/high power dipole antenna
  • 700-2700MHz
  • Up to 175W power rating


  • Compact wideband dipole antenna
  • 2-8 GHz
  • 20W power rating

Magnetic Mount Antennas for Rapid Deployment

COJOT prides itself on understanding client needs. Where a quick setup and removal is required or where the permanent installation of an antenna on a vehicle is not possible, our magnetic mount antennas are unparalleled.

Here are three of our most popular magnetic mount antennas:

WB460W (420 – 6000 MHz)

WB25512W (25 – 512 MHz)

WB30108W (30-108 MHz)

New Extended Beam Steering Antennas from COJOT

In a world where drone strikes are a near-daily occurrence, counter-drone measures are becoming increasingly important. At COJOT, we are working tirelessly on our beam steering antennas and proudly introduce two new versions with enhanced counter-UAS antenna functionality.

The new extended dual band SBA2456DB (10W) and high power SBA2456XDB (100W) are now covering the full 2 and 5GHz WiFi frequency bands (2.4 to 2.5 and 5 to 6 GHz), while providing the same excellent performance with up to 24 sharp beams and a minimum of 20-degree beamwidth to cover the full 360-degree horizontal area. The SBA2456 models are equipped with the latest updates of the COJOT SBA product family, including support for fast RS-485/422 and Ethernet interfaces as well as thoroughly environmentally tested mechanics – according to MIL-STD-810.

Fields of applications: Counter-UAS, Counter-Drone, EW, ISR applications

COJOT SBA product family:

C4i Band IV/C: SBA4450B and SBA4450XB

C4i Band III+/L: SBA1327B

5G: SBA3438B-DP

Direction Finding Antennas and Accuracy Part 2: Characterization of DF antennas

By Johan Fuhri, Product Owner

In the previous blog post we considered some of the ways in which we can express the performance of an DF antenna, and we noted that simply stating the ‘accuracy’ of a DF antenna is not quite that simple.  We also noted that there are various algorithms that can be used along with a typical DF antenna, and that the accuracy and sensitivity of DF system is dependent on both the quality of the antenna and the direction-finding algorithm.

In this blog post we will discuss the process of ‘characterizing’ a DF antenna array to generate a table of values which can be used in correlative algorithms. We will also look at a few real-life problems that cause inaccuracies in DF systems, specifically when using basic correlative algorithms.

What is a correlative algorithm?

Correlation is a mathematical and statistical tool that can be used to quantitively express how similar two or more sets of data are to each other.  It is basically a fancy way of playing ‘pick the closest match’.

To illustrate the process, we are going to use colour swatches (the type that adorns the walls of the paint department at your favourite hardware chain store) and create a simple direction-finding system.  Consider the image below, which is a circle divided into six sectors and a colour assigned to each sector.  Let’s suppose we have a DF antenna right in the center of this circle, and the lines/sectors represent the various directions from which a signal can arrive.  This, however, is a very special antenna, in the sense that it will tell you the colour of an incoming signal.

If we are clever, we can make sure that we install the antenna in such a way that a colour of our choosing, yellow in this case, is always pointing due north.  If we then receive a signal from our antenna (which will be a color, remember), we can compare the color that we received from the antenna with the image above to determine which direction the signal came from!  That’s not too hard now, is it?

On a very basic level, this is what correlative DF algorithms do.  The DF antenna is spun through 360⁰ and the incoming signal from each direction, on each of the elements on the antenna, is sampled and stored in a table.  This table is called the ‘characterization table’ (although different people might name it something else), and it effectively allows a DF system to calculate the exact direction from which a signal arrives by comparing the signal with those stored in the characterization table, just like we did with the colours.  The circle indicating which colour is in which direction is effectively our own ‘characterization table’.


Alaris Antennas offer characterization of our DF antennas and systems as a service to our clients.  These characterization measurements are most often done at an outdoor reflection range at the National Antenna Test Range just north of Pretoria, which we affectionately simply refer to as ‘Paardefontein’ (

The measurements entail mounting the antenna on one of the turntable towers and setting up a signal source some distance from the tower.  The DF antenna is then turned through 360 degrees in 4⁰ steps (depending on client requirements) and a sample captured from each of the elements of the antenna at each step.  This data is then compiled into a characterization table which we make available to our clients.

When life hands you green lemons…

As you might expect though, in real life things are not quite as simple.  There are various factors that can influence the accuracy of a DF system in real life scenarios, and in this section we are going to consider just a few of these, using our colour-wheel to illustrate why they cause problems.

Resolution of the characterization table

In our colour wheel example, we divided the circle into 12 sections, each representing an angle of 30⁰.  It is thus (nearly) impossible for us to determine the direction of an incoming signal to anything more accurate than about 30⁰.  Note that the signal to noise ratio, or the strength of the electric field, or the amount of noise has very little influence in the accuracy we can achieve, since we are fundamentally limited by the number of colours we have in our characterization table.

We can significantly increase our accuracy by dividing the circle into 36 smaller sectors, giving us many more options to compare our incoming signal to!  We can now determine the direction of our incoming signal to within a 10⁰ sector.


The original orange signal we received is most similar to the third sector, indicating that our signal arrived from a direction of 25⁰±5⁰.








The same is true for DF systems in practice as well.  When the antenna is characterized, the angle steps, or angle resolution, can be freely chosen by the person doing the measurement.  While it is tempting to choose super small steps (let’s measure a sample every 0.1⁰), this implies that the DF processor has do deal with a table that has 3600 entries, which can potentially slow things down to a crawl when limited processing power is available.  In practice, steps of between 2⁰ and 5⁰ are typically used, depending on the specific implementation of the client.

It is also worth mentioning that certain more sophisticated algorithms can achieve resolutions smaller than the characterization table resolution by employing all kinds of clever mathematical techniques.  It is the equivalent of being able to look at a greenish-yellow signal, and inferring that it must be somewhere between the green and yellow sectors, and thus giving a better guess than simply choosing the green or yellow sectors purely by similarity.  The details of these ‘super-resolution techniques’ are, however, often part of the proprietary magic that system integrators implement as their own competitive advantage.

The effects of noise

Up to now we assumed that the incoming signal that we are evaluating is perfectly clear, and that our accuracy is only limited by the resolution of the table against which we can compare our incoming signal.  In antenna terms this is called the ‘large signal accuracy’ of the antenna, as it assumes that no noise is present in the measurements.

Real life signals, however, rarely qualify as large signals and often has noise superimposed on the signal of interest.  Let’s look at an example in our colour wheel example.

Adding noise to the signal makes it harder and harder to find the colour that best matches the characterization table.  If there is noise present on the signal, invariably the DF processor will look at the ‘colours’ it can choose from and make mistakes.  At best it can tell you that the signal belongs to one of these four sectors, and this reduces the RMS accuracy of the overall system.

Adding even more noise, at some point it becomes practically impossible for the DF processor to make any sense of the incoming signal, and it may start taking ‘random’ guesses.  These wild guesses can be in any direction whatsoever, and are called appropriately called ‘wild bearings’.

The main source of noise in a DF system is the internal electronic components of the system.  Every amplifier, transistor and resistor contribute a bit of noise, and all this noise is added to the incoming signal before the DF processor has the opportunity to compare this signal to the characterization table. We can thus see that it is important to ensure that the received signal is as strong as possible while keeping the noise as small as possible to get a good signal-to-noise ratio.

The design of the DF antenna, specifically the gain of the antenna elements, directly contributes to keeping the SNR as high as possible by ensuring that the incoming signal is converted to a large as possible voltage for the receiver to work with.  For a more detailed discussion on this topic, refer to the previous blog post in this series.

Multipath interference

In certain scenarios it might be possible for a signal to bounce off objects, typically large buildings, and the signal that arrives at the DF antenna may end up being a combination of copies of the same signal, arriving from different directions.

These multipath signals, which we will illustrate as a mix of two colours, are very difficult for DF processors to deal with, and is very likely to a reduction in accuracy at best, or wild bearings at worst.


Using our colour wheel example, we can see that a pure green signal leaves the source that we are trying to find, but along the way a signal bouncing off a building also makes its way into the DF antenna.  The ‘colour’ making its way into the DF processor is mostly green, with a dash of blue mixed in.  This mixed signal will certainly cause problems for most simple correlative algorithms, as the received signal does not match any of the signals in the correlation table, causing inaccuracies and wild bearings.

Having said that, there are a few clever algorithms, like MUSIC, which can actually use these strange signals to its advantage and can figure out that there are multiple paths in play.  How these clever algorithms work is beyond the scope of this blog post (and the authors current intellectual grasp…).


This blog post attempted to explain the principle behind most correlative algorithms while trying to stay away from the complicated maths that make it work.  We also looked at a few real-world effects that influence the accuracy of DF systems in general, and specifically the mechanism that causes problems in correlative algorithms.  Most of these inaccuracies are caused by external factors, i.e. they are not so much caused by the design of the DF antenna, but by the environments in which they are employed.

In the last post of the series we will discuss a few of the intricacies of DF antenna design and how they can cause inherent inaccuracies (i.e. non-environmental causes) in poor designs.  This will be a rare glimpse into the everyday challenges that antenna engineers at Alaris Antennas deal with on a daily basis!