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By and large, frequencies above the audio band are called radio frequencies (RF). Although the term RF by definition, and I have checked in several text books including the American Radio Relay League (ARRL) handbook, is very broad, it is misunderstood by few in our industry to represent circuits and systems below the microwave line, which begins at 1 GHz. To further ensure that there is no ambiguity about the RF definition, I checked into McGraw-Hill's Electronics Dictionary. According to this dictionary, RF is a frequency at which coherent electromagnetic radiation of energy is useful for communication. Furthermore, the McGraw-Hill dictionary designated RF frequencies into various bands. These include very low frequency (VLF) below 30 kHz, low frequency (LF) in the 30 kHz to 300 kHz range, medium frequency (MF) between 300 kHz to 3000 kHz, high frequency (HF) in the 3 MHz to 30 MHz band, very high frequency (VHF) spanning from 30 MHz to 300 MHz, ultra high frequency (UHF) ranging from 300 MHz to 3000 MHz, super high frequency (SHF) spectrum as 3 GHz to 30 GHz, and extremely high frequency (EHF) covering 30 GHz to 300 GHz band. As we can see, RF represents a broad range of frequencies, which include microwave and millimeter wave frequencies.

Now, pioneers are also exploring the gap that exists between the microwave/millimeter wave frequencies and the infrared light waves, the tera Hertz (THz) frequencies — 1000 GHz or 1,000,000 MHz is 1 THz — for a new wave of military and commercial applications. But, we will get into that at a later time. For now, let us focus on the spectrum of interest to RF Design readers.

RF Design magazine was created some 26 years ago to serve the circuit design appetite of RF engineers. While the initial thrust of the magazine — for the first 15 years since inception — was on circuits and systems using frequencies below 1 GHz, as most of the commercial world including a huge portion of the military was designing in the UHF band and below, the focus of the magazine has expanded in the last 10 years in order to keep track of changes in the RF engineering world. As communication systems and other designers have moved up the frequency scale, so also has RF Design magazine broadened its scope to effectively cater to its readers. RF Design's expanded focus includes microwave and millimeter wave technologies. The aim is to disseminate the latest design information so that its readers (approximately 40,000 design engineers) can keep abreast of up to date developments on all RF fronts, starting from VLF and going into deep microwave and millimeter wave frequencies.

Since the proof is in the pudding, you may want to go to our site www.rfdesign.com and type in the word microwave in the search engine. I did. And, the engine identified 382 microwave-related articles written in the various sections of the magazine over the last four and a half years, including those covered in the e-newsletter RF Design Bulletin. By the way, the weekly e-newsletter was launched by the magazine only about a year ago. And the online magazine archives go back to the year 2000.

As Federal Communications Commission (FCC) and other world regulatory bodies are allocating bands in the microwave space for unlicensed wireless communications and other commercial, industrial and medical applications, more and more designers and product developers are tapping the benefits of microwave technologies. Therefore, it is no surprise that the military system designers are migrating to the millimeter wave spectrum and beyond. To furnish the cravings of military systems designers, the magazine offers a Defense Electronics supplement every quarter, in addition to covering advancements in this sector in the regular issue.