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 DefenseWill OpenRFM Shake Up the Microwave Industry?
By Barry Manz

Throughout the history of the RF and microwave industry there has never been a form factor standardizing the electromechanical, software, control plane, and thermal interfaces used by integrated microwave assemblies (IMAs) employed in defense systems. Rather, every system has been built to meet the requirements of a specific system, which may be but probably isn’t compatible with any other system. It’s simply the way the industry has always responded to requests from subcontractors that in turn must meet the physical, electrical, and RF requirements of prime contractors. 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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Another Sad Moment For the FCC
By Barry Manz

A significant number of rooftop antenna sites owned primarily by wireless carriers exceed FCC public and occupational exposure limits, make it impossible for workers to avoid standing in front of antennas, and are inadequately posted with warnings and barriers. The people who measure RF radiation levels at broadcast and wireless sites have known this for years.

Now a lot more people are getting the message, and it’s put the FCC (already smarting from the LightSquared debacle) in the position of trying to explain why it isn’t enforcing its own rules in the case of wireless carriers, all the while regularly nicking broadcasters for trivial infractions like not announcing their call sign at the top of the hour. Not a single fine has been levied by FCC against a wireless carrier for exceeding the limits.

The issue came to light last month when a group called the EM Radiation Policy Group sent out a press release announcing the results of work it had conducted to “unimpeachably” show that these problems exist, that the FCC ignores them, and that perhaps, just perhaps, it was because wireless carriers are good customers. That is, wireless carriers have added tens of billions of dollars to federal government coffers by buying the one thing the FCC has to offer: spectrum.

To provide proof of their accusations, the group paid a veteran RF radiation measurement specialist to test rooftop sites in 23 states, quickly finding more than 100 that were exceeding the limits (among other things) by up to 600%. It has posted videos on YouTube and its own Web site of rooftop installations, screen shots of instruments showing RF levels up to 600% above the standard, voice conversations with the FCC and wireless carriers, and the results of the group’s efforts to address the more than 100 complaints it has filed concerning specific sites (none of which, according to the group, the FCC has ever responded to). Some of the conversations would actually be funny if the issue wasn’t about safety.

The issue of whether or not non-ionizing radiation causes brain tumors, cancer, changes genetic structures, and a host other maladies has been around for decades and remains as contentious, politically charged, and odious as ever. The answer to the issue is that there is no answer, as “proof” would take long-term studies in man. The only undisputed fact is that microwave energy causes tissue heating, as anyone who owns a microwave oven can attest.

But that’s not the real issue here, which is that the FCC has rules and it doesn’t enforce them or enforces them selectively. These rules are designed to ensure that workers and the public are not exposed to high levels of RF radiation. The public and workers must be warned of and restricted from access to sites at which RF radiation levels are present. Every entity whose transmission equipment or industrial environment in which RF energy is present must ensure RF safety is maintained. The rules are extremely detailed largely agree with those of national and international standards bodies.

"Coincidentally", the FCC announced on March 29 that it is reviewing of its rules covering exposure limits to RF emissions from radio transmitters. The review is an effort to ensure FCC rules comply with the agency’s “environmental responsibilities and requirements,” and ensure that the public is protected from adverse effects of RF exposure. One goal is to reevaluate test methods and another is to essentially determine whether the cost of complying with the rules is commensurate with the perceived danger. However, even if the commission overhauls some of its rules, it won’t make any difference if it cannot or will not enforce them.

Barry Manz is a contributing editor to Microwave Product Digesting can be reached at



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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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