The Opportunities and Challenges of LTE Unlicensed in 5 GHz
David Witkowski, Executive Director, Wireless Communications Initiative
In 1998, the Federal Communications Commission established the Unlicensed National Information Infrastructure or U-NII 5 GHz bands. These are used primarily for Wi-Fi networks in homes, offices, hotels, airports, and other public spaces and also consumer devices. U-NII is also used by wireless Internet Service Providers, linking public safety radio sites, and for monitoring and critical infrastructure such as gas/oil pipelines.

Uncertain Times for DefenseOpen’s Systems and Changes in DoD Procurement: This Time It’s Real
By Barry Manz

The U.S. Department of Defense has a well-earned reputation for inertia. Many proposals for change are made – but nothing happens. The COTS initiative, which promised cost savings through the use of off-the-shelf commercial parts, sounded terrific at the time. It heralded a major departure from standard DoD procurement that more or less guaranteed that every system would be different in part because it used parts that were developed from scratch, leading to “one-off” systems that were very expensive. Read More...


Band Reject Filter Series
Higher frequency band reject (notch) filters are designed to operate over the frequency range of .01 to 28 GHz. These filters are characterized by having the reverse properties of band pass filters and are offered in multiple topologies. Available in compact sizes.
RLC Electronics

SP6T RF Switch
JSW6-33DR+ is a medium power reflective SP6T RF switch, with reflective short on output ports in the off condition. Made using Silicon-on-Insulator process, it has very high IP3, a built-in CMOS driver and negative voltage generator.

Group Delay Equalized Bandpass Filter
Part number 2903 is a group delayed equalized elliptic type bandpass filter that has a typical 1 dB bandwidth of 94 MHz and a typical 60 dB bandwidth of 171 MHz. Insertion loss is <2 dB and group delay variation from 110 to 170 MHz is <3nsec.
KR Electronics

Absorptive Low Pass Filter
Model AF9350 is a UHF, low pass filter that covers the 10 to 500 MHz band and has an average power rating of 400W CW. It incurs a rejection of 45 dB minimum at the 750 to 3000 MHz band, and power rating of 25W CW from 501 to 5000 MHz.

LTE Band 14 Ceramic Duplexer
This high performance LTE ceramic duplexer was designed and built for use in public safety communication and commercial cellular applications. It operates in Band 14 and offers low insertion loss and high isolation to enable clear communications in the LTE network.
Networks International

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Hope for the MRE: Microwave-Assisted Thermal Sterilization
Hope for the MRE: Microwave-Assisted Thermal Sterilization
Lauren Oleksyk at the Natick Soldier Research, Development and Engineering Center's Combat Feeding Directorate, is working to revolutionize what warfighters eat on the battlefield. “Our mission is to provide warfighters with near-fresh, high-quality, shelf-stable rations,” said Oleksyk, team leader for food processing, engineering and technology at the Soldier Research, Development and Engineering Center. “What we’re really going for is that even if they get something that may be three years old, for them to feel like it was made yesterday, or even that same day,” she said. To achieve this, they will, in part, relay on the utility of the ubiquitous microwave oven.

Meals, Ready to Eat (MREs), the centerpiece of the combat feeding program, are processed using retort thermosterilization, which is similar to canning, with items cooked at high temperatures and under pressure for as long as three hours to kill any bacteria. You get the sterilization that you need,” says Oleksyk, “but because it involves cooking a product for a long period of time, it can be detrimental to the product itself.”  Foods typically become stew-like, with mushy textures, bland colors and little flavor after extended cooking. The nutritional value drops, too. That led Natick engineers to explore new processing methods that commercial food service companies are emulating.

Microwave-assisted thermal sterilization is one of the most promising techniques. The process uses giant commercial microwave ovens that kill bacteria within just 8 min. and heats packaged foods uniformly in a way that traditional microwaves don’t. The result is higher-quality products with firmer textures, more natural colors, and fresher-tasting flavors, and it’s expanding what can be included in in combat rations.
Pasta, for example, tends to get mushy and lumpy using the retort method. The protein in fish and seafood breaks down, giving entrees a soft texture and an unpleasant “fishy” flavor and odor. Eggs take on a greenish cast. Fruits and vegetables become the consistency of baby food.

But a new developmental dish Oleksyk and her colleagues are advancing, Cajun chicken pasta, shows the difference microwave sterilization makes. When presented side-by-side with the same recipe processed using the retort method, the microwaved entree features al dente noodles, juicy chicken pieces and a just-cooked consistency and flavor.

“When you taste the microwave sterilized chicken, you really wouldn’t know that it was processed two years ago,” Oleksyk said. “You would think it was just prepared. And that is the goal.” A salmon-in-alfredo-sauce MRE under development using microwave sterilization delivers a firm texture and fresh-caught taste. “It’s shelf-stable for three years,” said Jeremy Whitsitt, technology integration analyst for the center’s Department of Defense combat feeding directorate.




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MMD March 2014

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The Design of Ultra Narrowband Amplifiers Using Small-Signal Varactor Upconverters
This paper presents a method of realizing tunable microwave amplifiers with ultra narrow bandwidths that can be less than 0.5% by the use of a varactor up-converter (UC).
Planar Monolithics

Directivity and VSWR Measurements
Return loss and VSWR measurements are complicated by the finite performance of the directional device used to measure the reflected power. The only accurate and convenient way to make return loss measurements is with a well matched high directivity directional coupler or bridge.
Marki Microwave

Switch Solutions for Systems with Low PIM Requirements
Dow-Key Microwave has invested in R&D for new RF switch products designed specifically to reduce intermodulation (IM) in coaxial switches.
Dow-Key Microwave

How to Specify RF and Microwave Filters
Covers cavity, ceramic, LC, crystal and helical filters.
Anatech Electronics

Mounting Considerations for Medium Power Surface-Mount RF Devices
Covers all factors that must be considered when mounting SMT devices.
TriQuint Semiconductor

Biasing MMIC Amplifiers
How to bias MMICs along with theory and techniques.

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