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Industry News

A Compact, High Power 2.45 GHz Microwave Generator

May 6, 2010
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The requirement for low cost, light weight, compact and portable laboratory equipment is becoming more commonplace in industry. In the field of microwave test and measurement, customers are increasingly demanding complete, fully functional and certified systems that meet industrial standards. To provide customers with this complete solution, Emblation Microwave has developed the ISYS245 microwave generator.

This new model uses state-of-the-art technology to produce a highly efficient 2.45 GHz microwave system capable of generating variable power in excess of 110 W at 2.45 GHz with superior reflection measurement capability and temperature stability. The ISYS245 has been designed with an easy to use interface with the capability of being operated as a standalone system or externally controlled via PC and/or microwave signal generator.

APPLICATIONS

The use of microwave technology in communication, industrial and laboratory applications is constantly advancing with high power capability becoming a necessity. Also, curing and drying applications as well as microwave chemistry are reliant on systems being developed specifically for their applications, based on modified, readily available microwave amplifier modules at a significant development cost to the end user. The additional cost to have the systems safety tested and certified for use and sale adds to both the financial and time to market burden.

However, the ISYS245 allows the user to take advantage of a compact off the shelf system and incorporate it into their existing laboratory/process setup/product design. With simple interfacing and ease of control, the ISYS245 is readily adaptable for a number of uses in industrial, scientific, medical, instrumentation and food science.

Potential applications include:

  • Microwave measurement – material analysis (moisture), test & measurement, university research (hyperthermia/ablation, antenna measurements and wireless communication research)
  • Microwave chemistry – organic chemistry, liquid phase reactions, intercalation reactions, organo-metallic chemistry, polymer chemistry and solid-state chemistry
  • Manufacturing – polymer curing, material heating and drying, ceramics testing, plasma discharge devices for UV curing and epoxy adhesive curing
  • Food science – meat tempering and curing and material analysis (moisture, salinity, density)

Figure 1 Saturated output power of ISYS245.

OPERATION

The microwave amplifier uses GaN on SiC solid-state technology, operating in Class AB mode to generate microwave power in excess of 100 W CW, when used in the internally regulated standalone mode (as shown in Figure 1). In this mode and the swept mode, the output power can be varied in 5 W increments from 0 to 110 W using pulse width modulation (PWM) techniques with power stability maintained within 5 percent of the set value.

The ISYS245 can also be used as a standard amplifier when used in external source mode, where a small-signal gain of 55 to 58 dB is typical. Using this mode of operation, the amplifier operates without any internal power regulation, allowing the user to have full control of the output power levels. A performance summary of the ISYS245 is shown in Table 1.

ADVANCED REFLECTION MEASUREMENT

The ISYS245 has, as standard, an innovative reflected power measurement mode of operation. When used in the swept mode, the system has the capability to reduce the reflection measurement error significantly when the input match of the device under test is non-optimal. As an example, for a device with an input match of -12 dB connected to the system at a distance in excess of 1 m, an improvement of approximately 75 percent in measurement error is easily achievable, thereby reducing the overall uncertainty in the measurement. This mode of operation is particularly useful for applications that are dependent upon the accuracy of a reflected signal to identify material properties or relaying test progress and safety.

Figure 2 ISYS245 amplifier efficiency and temperature stability.

IMPROVED COOLING

The use of higher operating voltages on the GaN on SiC semiconductors in the ISYS245 system design helps reduce the drain current and the resultant Joule effect losses. The system has an amplifier efficiency of ~62 percent, resulting in a low channel temperature rise and also significantly reduced thermal loss, requiring reduced thermal management (see Figure 2).

The ISYS245’s efficient design has facilitated the implementation of a novel, thermal cooler solution to dissipate heat losses and maintain the amplifier temperature when operating at full power at below 55°C. The cooling system employed is very compact with superior thermal capacity per unit volume, enabling the overall system to be significantly smaller and lighter, with an optimised air-flow management system.

SIMPLE USER INTERFACE

The microwave generator’s user interface has been ergonomically designed for ease of use, with an intuitive interface having all controls in full view of the user. The system has three main controls for basic operation: the Output Power setting has increments and decrements in 5 W steps; as for the Reflection Power Trip setting, if a process requires the microwave power to be disabled when a certain reflected power level is detected, this function will allow that trip value to be set. This function increments and decrements in 1 W steps; with the Timer setting the system has the option of being used in continuous or timer mode. When used in timer mode, the time can be set up to 99 minutes. When the microwave power is enabled, the timer function will decrement in 1 second steps and disable the microwave power when the timer reaches zero. All information is displayed on a high contrast white LED display.

The system also has six function buttons: the RF On button enables and disables microwave power; the Swept button, when used in standalone mode, allows an improved accuracy measurement of real-time reflected power to be made and displayed; the Timer button is for when the user requires to have power automatically disabled after a predetermined test duration; the External Source button is for use with the users’ own signal generators via an SMA female connector on the rear panel; the External Control is for when data logging or specialised control is required via the parallel interface on the rear panel. This function disables the front panel controls. This mode allows the user to fully control the system including the output power through a time or reflection dependent power profile to get a unique power characteristic response. Lastly, the Reset button resets the system back to the power-on values.

With RF On enabled, the system displays the real-time measurement of both the output and reflected power, and warning LEDs and audible alarms are included in the ISYS245 as standard. The output power is delivered to an N-type (female) on the front panel, with all external control on the rear panel via an SMA (female) RF input and parallel data control interface.

FUTURE DEVELOPMENTS

The external communication is currently carried out using a simple parallel data communication interface. However, a USB module is in the final stages of development, which connects to the ISYS245, thus enabling full control and data logging capability via a USB interface to a PC. All communication software will be provided with the USB module. The external software adds to the system flexibility and can be customized for the user for their specific development purposes. Other systems under development include higher frequency applications and OEM/ODM systems designed specifically for highly regulated sectors.

CONCLUSION

With the introduction of the ISYS245, Emblation Microwave is providing an affordable, light weight and compact, fully packaged solution with all the functionality and performance that is expected in today’s high power marketplace.

Emblation Microwave,
Alloa, Scotland, UK,
Tel: +44 (0) 1259 236132,
Fax: +44 (0) 1259 210430,
info@emblationmicrowave.com,
www.emblationmicrowave.com
RS No. 303

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