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.

MMD March 2014

Previous issues click here


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

See all products in this issue


June 2013

Interference in the Second Wireless Revolution

By Sam Benzacar, President, Anatech Electronics

Fred Ortiz, President, dB Control

In the late 1980s as the microwave industry faced a dramatically reduced U.S. defense budget (from which most of its revenue came from), something remarkable happened: The aptly-named Wireless Revolution appeared seemingly overnight, creating an entirely new revenue source for our industry. Three decades later, we also have a declining defense budget and the emergence of the Second Wireless Revolution, delivered by high-speed data transmission and advances in every technology used to build infrastructure and wireless-enabled devices. This revolution is just beginning and there is no end in sight, as LTE Advanced is on the horizon and distributed antenna systems and small cells are creating a market within a market that never existed before.

However, there’s a fly in the ointment this time around: significant interference issues that affect everyone from component to subsystem manufacturers as well as wireless carriers that was far less onerous in Wireless Rev. 1. Having consumed large amounts of spectrum through the first-through-fourth generations of wireless evolution, frequencies below 3 GHz are jam-packed with signals. This level of spectral density is placing huge burdens on transmit and receive chains to keep signals “clean” with amplifier designers no doubt feeling the pinch more than others. Squeezing new services into a finite spectrum with minimal guard bands makes interference inevitable, a problem that has been and will continue to be solved by filters, both inside user equipment and inside and outside base stations.

As a filter manufacturer, we’re (happily) on the receiving end of requests for extreme in-band signal rejection, extremely low passive intermodulation distortion and insertion loss, and other requirements that bump up against what physics makes it possible to achieve. For distributed antenna systems (DAS), small cells, and Wi-Fi hot spots, interference is looming ahead as a potentially enormous issue. DAS and small cells must work together with their macro cell counterparts in the same place at the same time. In a stadium, example, a DAS may have dozens of nodes all within a relatively small area. Wi-Fi hotspots have always been required to function together with Bluetooth, but there are more hotspots popping up every day as cable companies provide them as a “value-added” customer feature and wireless carriers use them for backhaul. In addition, small cells – basically any base station other than a macro cell – will face the same interference issues as they are widely deployed.

Contrary to what many in the industry believe, cavity, LC, ceramic, and crystal filter technology has not remained stagnant. The laws of physics obviously place limits on what a filter (or any other RF or microwave component) can achieve, but through the use of both tried-and-true filter design and manufacturing techniques along with greater manufacturing precision and prudent use of today’s 3D design software and filter synthesis tools, the levels of performance that filters can achieve can be extended to accommodate what all sectors of the wireless industry are most assuredly going to need in the years ahead.

That’s good news for everyone, because interference isn’t going to become less an issue in the future and it must be effectively mitigated for wireless networks to work “harmoniously” together with the inevitability of vanishing guard bands and new services shoehorned between existing services.

Anatech Electronics
Email this article to a friend!



You Can
Search by Number:

  All ads, articles, and products in printed issues of MPD have a number. Just look for the red arrow in the ad or at the end of the article or product description.


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...

Home | About Us | Archives | Editorial Submissions | Media Kit (PDF) | Events | Subscribe/Renew | Contact Us
Copyright © 2014 Octagon Communication Inc. DBA MPDigest /, All Rights Reserved.
Privacy Policy | Site Map