Electromagnetic simulation tools accelerate design of microwave amplifiers - automated process allows travelling-wave-tubes to be designed and analyzed in minutes!
automated process allows travelling-wave-tubes to be
designed and analyzed in minutes!
An automated simulation-based design cycle has become a
fundamental part of the success of one of today's leading designers
of travelling wave tube (TWT) microwave amplifiers.
TMD Technologies produces a large range of TWTs, a core component
of many radar and missile seeker systems, electronic counter
measure (ECM) and electronic warfare (EW) systems. By using
scripting tools built into Cobham Technical Services' Opera
electromagnetic design software, the company has created a custom
tool that automatically builds a three-dimensional (3D) model of a
new TWT, simulates it and analyses the results, all within the
space of around five minutes. This speed of design provides the
engineering team with a means of rapidly creating highly-optimized
solutions for new TWT applications, allowing the company to respond
quickly and effectively to this largely project-driven
business.
TMD is one of the oldest companies in the TWT marketplace, with
roots dating from the early 1940s, when as the microwave tube
research division of EMI Electronics it developed high power
klystrons for the first airborne radars. Today, the company retains
a leadership position in several TWT design segments including
ring-loop and coupled-cavity types, and particularly in the
higher-power parts of the market. The company's ability to design
specialized high-voltage low-noise power supplies required for TWT
applications, and to provide integrated transmitter subsystems is
another major factor behind the company's recent growth.
Automation of the design process is critical, as simulation is the
main means of understanding the effects of design changes on TWT
performance. Although there are markets for standard TWT products,
a large proportion of the business is application-specific and TMD
often has to balance several competing design goals in order to
produce the required characteristics. Along with frequency and
amplification specifications, there are often severe weight, size,
power consumption and heat dissipation targets for example, as
systems might be installed on satellites or aircraft. The ability
to design a TWT that is compatible with the voltage levels of an
existing power supply is another common demand, as this can
substantially reduce project costs and timescales.
The Opera-based electromagnetic design tool provides TMD with a
powerful means of exploring the solutions to these design
challenges. The tool has a library of generic parameterized models
of TWT tube designs, containing unique intellectual property on the
design of component parts of TWTs, and all the engineer needs to
start creating a custom TWT is to enter some of the model geometry
parameters using dialog boxes - which takes only a few minutes. The
package will then automatically simulate and post-process the
results to provide custom high-level views of the resulting
performance.
This process typically takes less than five minutes, so it is easy
for TMD to modify the design parameters and repeat the analysis to
locate the optimum solution within any chosen design space. TMD
also has built in special features to the custom design software to
improve the optimization process, such as making it easy for users
to suspend simulation and change parameters on the fly, or to
'bracket' a design topology and then to create an interpolated data
file that can be used to explore the intervening design space.
Thanks to the highly automated design optimization, this phase of
the total TWT design process can often be accomplished within a
couple of days. TMD has also produced similar script sequences that
partially-automate the design of the electron gun and magnetic
focusing elements of a TWT.
One of the most recent applications for the automated design tool
has been in the development of a groundbreaking microwave power
module called PTX8400. The compact transmitter module provides 1 kW
output thanks to a novel ring loop TWT offering very high gain.
This combination of size and performance is setting a new standard
for space- and weight-critical radar applications such as unmanned
aerial vehicles (UAVs) and military helicopter platforms.
TMD has been using the Opera software suite from Cobham for over
10 years. The company utilizes many of the specialist
electromagnetic design solvers developed by Cobham including ones
for simulating charged particle beams, for static and time-varying
magnetic field analysis, and for modelling thermal effects. The
accuracy of the finite element analysis design software has been
proven time and again for the company, by comparing actual measured
results from the finished real-world products with the predictions
obtained from the simulation models.
"The Opera-based tools that we have developed substantially
shorten design cycles, giving us a lot of time and freedom to find
the best solution for any particular application," says David
Dyson, Chief Engineer of TMD Technologies' Tubes Division.
Travelling wave tubes (TWTs) are vacuum devices that amplify by
producing an electron beam and coupling it with a microwave
frequency electromagnetic signal. Synchronization is achieved by
means of a 'slow wave structure' which employs a geometry such as a
helix, ring bar or ring loop to precisely delay the microwave
signal by forcing it to meander back and forth.
About TMD Technologies
TMD Technologies Ltd is the world's foremost supplier of rugged
high power amplifiers and transmitters for radar and electronic
warfare (EW) applications. TMD supplies most of the major radar and
EW systems companies worldwide, and has an unrivalled reputation
for technical innovation, particularly in the area of low noise
performance. It is also an important supplier to the EMC testing,
communications, scientific and medical markets. In addition to
rugged amplifiers and transmitters, TMD's capability covers
microwave tubes, cathodes and electron guns, high voltage power
supplies, instrumentation microwave amplifiers and special assembly
projects. The origins of TMD can be traced back to the high power
klystron group of EMI which was involved with development of the
first airborne radars during the 1940s. Since then, as part of EMI
and later Thorn, TMD has been responsible for many of the major
technical advances in the microwave tube industry, and over the
last 25 years has expanded into the areas of switched mode power
supplies and transmitters. TMD Technologies was created in 1995
following a management buyout from Thorn EMI. For more information
please contact Heather Skinner at: TMD Technologies Ltd,
Swallowfield Way, Hayes, Middlesex UB3 1DQ, UK. t +44 (0)20 8573
5555; f +44 (0)20 8569 1839; wecare@tmd.co.uk; http://www.tmd.co.uk