Flann Waveguide

[Dezzyy Correiro]

Forsome applications, where full waveguide band operation is not essential, it might be desirable to opt for an optimised VSWR performance over a narrow band. For such applications Flann are able to offer narrow band models with a typical VSWR of beter than 1.05 depending on waveguide size and operating frequency range. Please contact our Sales Office in the first instance for assistance to identify the most suitable model for your requirement. Models are available fitted with either Male or Female SMA connector. Narrow band models fitted with Type N connectors are also available. Please see Series 094-NF**for details.

We are proud to include in our latest catalogue, our new series of WRD waveguide to coax adaptors which have been designed to give high durability and reliability. Adaptors can be fitted with SMA, APC7 and N type connectors for use up to 18 GHz, K connectors are fitted to the WRD 180 units covering the 18 GHz to 40 GHz band. Narrowband models, specifically optimised can be manufactured on request.

Flann Microwave Ltd is a global market-leading designer and manufacturer of precision passive RF, Microwave and Millimetric products, solutions and services. For almost 70 years Flann has set the bar for performance and reliability. Our workforce of 65 highly skilled engineers and professionals enable us to export 85% of turnover annually.

Flann produces critical components and sub-systems required to deliver, test, measure, and calibrate systems operating from 300MHz to 1.1THz. Our technologies range from components such as: antennas, diplexers, adaptors, attenuators, switches, couplers, terminations, through custom waveguide assemblies to integrated networks.

Being able to change the signal power of an RF system is a fundamental need. There are many reasons why it is preferable to attenuate the signal close to the source. When developing and testing a new product, it is often useful to bring the input power up slowly to avoid damage and to ensure proper characterization. When a vector network analyzer is calibrated, an absolute standard such as a TRL offset enables accurate results. When the transmission medium is waveguide, power levels may be controlled with a waveguide attenuator.

The industry standard defines an attenuation value as a ratio of the input power to the output power, expressed in decibels (dB). However, to fully specify an attenuator, the user must understand the specific requirements of the application. Some of the specifications will involve determining:

These specific requirements are combined with requirements for cost, quantity, size, mass, environment, integration and control to determine the most appropriate waveguide attenuator solutions for a particular application.

The mix of waveguide solutions reflects the market segmentation. Automatic test and programmability have become important test attributes, driven by factors such as the growth in data traffic, more sophisticated testing equipment with closed-loop feedback, manufacturing advances, evolving digital control in IoT applications and advances in design tools such as finite element modeling analysis. These test and measurement applications are likely to use variable attenuators for the continuous attenuation that they can offer.

Flann Microwave believes that future market growth for products will come from ATE applications and competitive pricing. Flann offers standard rotary vane attenuators that deliver high accuracy over a full waveguide band. They have a flat attenuation profile versus frequency and have attenuation ranges from 0 dB up to 60 dB. This style of attenuator comes in various forms with both manual and programmable versions for ATE applications. Some examples of these attenuators are shown in Figure 1.

Figure 2 shows a plot of attenuation versus frequency for the 29625-03 attenuator shown as the first device in Figure 1. This device operates in the WR-06 waveguide frequency band with a flat attenuation response over this 110 to 170 GHz range. The Flann rotary vane attenuator family is capable of operating up to 500 GHz.

While this family of attenuators offers excellent performance, some applications may require a smaller size with a device that is less costly and easier to manufacture. For these applications, Flann provides a basic variable attenuator. These designs are easy to manufacture, compact and low-cost devices. The trade-off with these devices is an attenuation range of 0 to 25 dB or 30 dB and 40 to 60 percent attenuation variation with frequency, along with a simple lookup table that varies for every frequency for calibration.

The applications for this low-cost family are also limited by the method of changing attenuation. Historically, devices of this type have used a manual micrometer to adjust attenuation. Automating the attenuation process requires a compact actuator that would be of comparable size to the attenuator. The cost and size of these actuators have been prohibitive, but suitable actuators are becoming available and Flann is re-evaluating the design approach.

Introducing a product suitable for high performance ATE applications meant minimizing the disadvantages while maintaining the advantages of the low-cost versions. To achieve this, Flann designed programable/remote attenuation control from a PC using a USB interface with power. The attenuation range was increased to 50 dB and the attenuation flatness was improved to 10 percent. All this was accomplished with an eye toward reduced size and moderate cost targets.

Combining the RF design with an actuator having a 5 μm resolution enables the specifications shown in Table 1. In addition to the performance, the design uses an element that is entirely retracted from the waveguide at the minimum attenuation value. This ensures that the insertion loss of the device is the only insertion loss of the waveguide as this will be an important advantage as frequencies go higher.

The team at Flann played a key role in the development of the new Institute of Electrical and Electronic Engineers (IEEE) standard IEEE 1785, which sets requirements for waveguides from 75 GHz to 3.3 THz. Previously there was no internationally agreed standard for waveguides operating above 330 GHz.

With a 60-strong team based in Bodmin, Cornwall, UK, Flann Microwave has grown over six decades to become the market leader in the design and manufacture of precision waveguide components and testing and calibration equipment, serving customers in the telecoms, government, automotive, aerospace, defence and research sectors.

The Flann team has been working with the IEEE Standards working group since it was formed in March 2008, and the interface drawings in the new IEEE standard were produced by Flann mechanical engineers.

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With a 60-strong team based in Bodmin, the company has quietly grown to become a market leader in the design and manufacture of precision microwave communications equipment, for example, to allow Internet and mobile data to be carried between mobile phone masts or through satellite links.

Its innovations have been pivotal in the development of mobile telephone networks, from the very inception of the technology through to the huge growth in mobile use over the last two decades and right up to ongoing research into the next generation 5G communications.

Flann also makes critical components and test equipment for waveguide-based applications as diverse as national air traffic control and airport security systems, traffic light radar sensors, collision avoidance technology for cars and secure communications networks.

Flann was founded in Kingston upon Thames, Surrey, in 1956 by engineer Bernard Fleming, who took his experience in radar and combined this with a passion for innovation and insight into the potential of waveguide technology.

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