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RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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Anatech Electronics, a manufacturer of RF and microwave filters, has published its October 2015 newsletter. As always, it includes both company news and some tidbits about relevant industry happenings. This month, Sam Benzacar theme is "Spectrum Pollution: A Silent Menace." He discusses a test run by a spectrum monitoring setup that recorded thousands of independent signals in the 2.4 GHz ISM band in an urban environment, illustrating how saturated our environment is with RF energy, and making you wonder how anything even works under those conditions. It's no wonder cellphone and OIP calls are often so crappy. Oh, how I miss the old twisted pair landline telephone calls, with never the need to ask, "Can you hear me now?"
By Sam Benzacar
Pollution of the electromagnetic spectrum is something very few people think about. After all, you cannot sense it or otherwise detect its presence "organically". But you know it's there if you listen to AM radio, your microwave oven and Wi-Fi "collide", and in many other ways you simply take for granted as a nuisance. But the simple fact is that every electrical or electronic device emits radiation, some of it at very low frequencies, and the rest scattered throughout the spectrum used by everyone from amateur radio operators to wireless carriers.
To prove this point, I recall a story told me by an associate about one of his clients located in Virginia near Washington, D.C. that manufactures very-broadband spectrum recorders that capture signals off the air. The systems ingest areas of spectrum up to 1000 MHz wide for spectrum monitoring and surveillance purposes. When his company was testing a prototype a couple of their engineers stuck a length of wire into its antenna terminal and recorded the activity within 200 MHz of bandwidth centered at 2450 MHz where Wi-Fi, Bluetooth, and other services operate. The length of the recording was only 1 minute.
In this time, the company's proprietary software counted nearly 6,000 emitters of various signal strengths and waveforms, even though the system (and the wire) were inside the building. They were so amazed at the result that they opened up the bandwidth to 500 MHz, and counted nearly 80,000 emitters. As signals at this frequency are not typically very strong nor travel very far, the interference was coming from relatively close by. It's safe to assume that if they made their recordings at a lower frequency such as 700 MHz where signals travel further, they would have recorded even more signals.
Such is the electromagnetic environment we have created, in which the ability to communicate is stymied by the sheer number of fundamental, harmonic, and spurious signals that are present in urban and suburban environments. And it's safe to assume that as the number of devices of various kinds proliferate, the problem will become worse and worse. And remember, we are soon to have a whole new class of machine-to-machine emitters thanks to the coming boom in connected devices.
I don't have the answer to the increasing problem of spectrum pollution, nor do I suspect does anyone else, but it may ultimately become so overwhelmingly difficult to deal with that "something" will have to be done.
In the meantime, Anatech Electronics offers, as it has for more than 25 years, solutions for an enormous array of interference problems that can be dealt with using RF and microwave filters. We're here to help when you need it. Please call us at (973) 772-4242 or send us an email by clicking here.
Think TWTs, klystrons, gryotrons, and other Vacuum Electronic Devices (VEDs) are ready for the history books? No so fast. ABI Research in its report "Microwave and Millimeter Wave High-Power Vacuum Electron Devices: One of Electronics' Original Technologies is Going Strong" values their global market at a stable $1 billion or more. The reason is that there is no other technology that can generate anything close to the enormous amounts of power that "tubes" can produce, and some applications, such as some radars, scientific and medical systems, and satellite communications systems, need it. ABI Research Director Lance Wilson summed it up nicely: "In some cases there is no other way to generate such high levels of RF power within an acceptably small space. Certain microwave and millimeter-wave VEDs can generate megawatts, and it would take tens of thousands of transistors to do that."
You'd think America would be a world leader in LTE download speed from wireless carriers, but the truth lies elsewhere. Specifically, at the bottom of the list. According to a report from Open Signal from whom the chart below was taken, the U.S. is below every other country on the list, at a paltry 10 Mb/s. The report itself is excellent reading, if you can stand to be frustrated. Open signal link.
As a result of many people trying unsuccessfully to find and identify family members buried at the Santa Clara Cemetery, the Village of Santa Clara, NM, called in specialists to use ground penetrating radar. The problem, as reported in the Silver City Sun-News, is that some families had no money for headstones and used piles of rocks and wooden crosses instead, and with the rocks being disrupted or the crosses withering away, there was no obvious way to find and identify them. Graves marked with headstones, field stones, or mounds accounted for only about two-thirds of the 1,397 burials but the radar revealed 497 that had been lost in the cemetery's 149-year old history. Metal crosses are now being made to locate them in the hope that family members will come to identify them.
Defense Secretary Ashton Carter told attendees at a DARPA conference in St. Louis that DoD intends to protect funds designated for research into new space, cyber, and EW weapons, owing to rapid technology developments by China and Russia that are letting them catch up to the U.S. This is not first time Carter has expressed his concern over the issue and DoD has of late made strong statements about how urgently the agency needs to collaborate with private industry to harness commercial capabilities in order to speed leading-edge developments. The result for companies serving these markets is increased funding not likely to be hacked out of the budget.
Anatech Electronics, Inc. (AEI) specializes in the design and manufacture of standard and custom RF and microwave filters and other passive components and subsystems employed in commercial, industrial, and aerospace and applications. Products are available from an operating frequency range of 10 kHz to 30 GHz and include cavity, ceramic, crystal, LC, and surface acoustic wave (SAW), as well as power combiners/dividers, duplexers and diplexers, directional couplers, terminations, attenuators, circulators, EMI filters, and lightning arrestors. The company's custom products and capabilities are available at www.anatechelectronics.com and standard products are available for purchase at the Anatech Electronics integrated Web store https://www.anatechelectronics.com/index.php/webstore
Anatech Electronics, Inc.
70 Outwater Lane
Garfield, NJ 07026
Posted October 14, 2015