Wi-Fi

A great book about RF circuit design just got better

Most, if not all, mobile devices have an RF component and RF Circuit Design 2E tells the reader how to design and integrate that component in a very practical fashion.

Christopher Bowick and his book RF Circuit Design have been helping people understand the intricacies of RF design for almost 25 years. Well, Mr. Bowick has stepped it up a notch by creating a second edition with new information. The following synopsis of the book mentions the new areas covered by the book.

"RF circuit design is now more important than ever as we find ourselves in an increasingly wireless world. Radio is the backbone of todays wireless industry with protocols such as Bluetooth, Wi-Fi, WiMax, and ZigBee. Most, if not all, mobile devices have an RF component and this book tells the reader how to design and integrate that component in a very practical fashion."

I bet most members are saying, sure another really boring or over the top book that only totally geeked out RF nuts like myself would like. Maybe, but I thought I would at least allow people who are even the least bit interested a chance to see for themselves. It so happens, RF DesignLine has published excerpts from various chapters of the book, starting with "Understand Radio Architecture, Part1". There are five excerpts in total, each describing a certain aspect of RF design. Just reading these alone is well worth the time. For example, I included a section where the author talks about the relationship between noise factor and the signal to noise ratio:

"Front-end receiver components are characterized in terms of noise by several parameters, including noise figure (NF) and noise factor (F). For the receiver as a whole, the noise factor is simply a ratio of the SNR at the output of the receiver compared to the SNR at the source of the receiver. For each component, similarly, the noise factor is the ratio of the SNR at the output to the SNR at the input. The noise figure is identical to the noise factor, except that it is given in dB."

While at this Web site and on the topic of RF propagation, I thought it might be beneficial to point out another quality article written by Ryan Winfield and Mark Gerrior, "Avoiding Interference in the 2.4 GHz ISM band." The RF environment, especially the 2.4 GHz frequency band, is seeing an increasing amount of what could be called RF pollution and noise. The article goes beyond the normal "what is wrong" in that it explains the new technology equipment designers are trying to incorporate into BlueTooth, Wi-Fi, and ZigBee products to reduce the detrimental effects of interference.

Final thoughts (and I moved)

I normally like to give a fresh perspective on topics, but these articles are very well written by experts, so I thought it best not to meddle.

I also wanted to mention that, in order to better serve the members, TechRepublic  has realigned the wireless networking and infrastructure blog to be a subset of the Network Administrator blog. It is a special privilege to be among some very sharp writers in this section. I hope I can live up to their standards. Its pretty exciting to be able to write about both wired and wireless networking.

About

Information is my field...Writing is my passion...Coupling the two is my mission.

5 comments
BALTHOR
BALTHOR

Digital is pulses of DC and RF is that analog sine wave stuff.My first question would be how can anybody multiplex DC on to AC.I'd have to see the wave.

TheChas
TheChas

First off, ALL digital signals include RF components. All of the one's can be expressed as a series of increasing frequency sine waves starting with the base frequency of the pulse. That is why it is easy for someone to spy on a computer from a distance. Second, all of our digital communications are composed of ones and zeros modulated onto a RF carrier. The higher the baud rate, the higher the frequency of the modulation itself. All computer hardware designers need to pay attention to the physics and realities of RF waveform propagation. Otherwise, the date word you send across the data bus gets jumbled or even mixed up on the way. In fact, the realities of high speed data transfer is why we have serial ATA and PCI Express. It is just too difficult to send a parallel data word at higher data rates. So, there is RF in your data, and data on your digital encoded RF communications. Chas

Michael Kassner
Michael Kassner

When discussing RF propagation, digital usually refers to the modulation of the RF signal which is analog. There are a multitude of digital modulation techniques and all use three basic analog wave variables. Those would be amplitude, frequency, and phase. Each of these phases, frequencies or amplitudes are assigned a unique pattern of binary bits. The number of bits comprises the symbol that is represented by the particular analog wave variable. A very simple example of digital modulation would be that of Morse code which uses continuous wave RF signal. Continuous wave is a carrier wave that is switched on and off. Information is carried in the varying duration of the on and off periods of the signal. Did the articles prove of interest?

normhaga
normhaga

That is kind of what you are doing with DC loading of a coil. A coil, whether an RF choke, impedance matcher, or a transformer has better characteristics and efficiency when loaded with a DC current even though it is an AC device.