Relevant Links

With the exception of amateur radio, there’s not really that much scientific info on the web about antennas (but lots of companies are selling poorly documented things) so here is what I can find in the way of helpful websites.  

 

Relevant Links:

·          http://en.wikipedia.org/wiki/Antenna_(radio)

o        Wikipedia is always a good place to start

·          http://www.ac6v.com/antprojects.htm

o        “AC6V's Homebrew Antenna Links Including Antenna Theory”

·          http://www.arrl.org/qexfiles/0105downs.pdf

o        “Why Antennas Radiate” by Stuart Downs – the ARRL is a GREAT resource, check out arrl.org

·          http://www.classictesla.com/download/emfields.pdf

o        “Understanding electromagnetic fields and antenna radiation takes (almost) no math”

·          http://www.wa5vjb.com/

o        Low-cost PCB antennas

·          http://www.microwaves101.com/

o        A great site that deals with microwave components - an antenna has to connect to something, doesn’t it?  Check out the downloads section for a nice Smith Chart and some handy spreadsheets

·          http://www.rfcafe.com/

 

E-books:

·          http://www.ece.rutgers.edu/~orfanidi/ewa/

o        Electromagnetic Waves and Antennas, an e-book by Sophocles Orfandis

·          http://web.mit.edu/6.013_book/www/

o        Electromagnetic Fields and Energy, by Haus and Melcher from MIT’s Hypermedia Teaching Facility

 

 

Antenna References

This blog will of course not be able to explain everything about the theory of antennas. These are my three favorite antenna reference books:

• Antennas: For all Applications, John D. Kraus and Ronald Marhefka
• Kraus was a genius in the field of antennas and has written an excellent textbook. If you really want to UNDERSTAND how antennas work this is the book for you. Since he passed away it is becoming harder and harder to find, so you may need to head to the library.
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• Antenna Theory: Analysis and Design, Constantine Balanis
• Balanis is another excellent author and his book is more math-intensive than Kraus. This is the book to use if you want design equations for antennas.
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• Antenna Theory and Design, Warren Stutzman and Gary Thiele
• This book is great because it contains a little of everything. It walks the middle road between Kraus and Balanis, but it has everything you need to know. The chapters on computational electromagnetics are outstanding.
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Of course, a knowledge of electromagnetics is essential groundwork for the study of antennas:

• Electromagnetics with Applications, John Kraus
• Again, Kraus' book is focuses on conceptual understanding and is not very rigorous. But if you want to see the basic principles of electromagnetics explained clearly, this book is great.
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• Introduction to Electrodynamics, David J Griffiths
• This book is the widely acclaimed introduction to using the principles of vector calculus on electromagnetic problems. If you want to see the power and beauty of Maxwell's equations, I highly recommend this book.
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What is an antenna?

Though I suppose this post will be the least useful for anyone who is already on this site, nonetheless, I feel the need to discuss what it is that an antenna actually does...

An antenna is a electromagnetic transition between a circuit and the medium around it. For instance, cell phones have an antenna that radiates energy towards the tower, allowing you to talk. Radios have antennas that absorb energy, literally grabbing the signal, and hence the music, out of thin air. A physicist might describe an antenna as a device that transitions from the electrons flowing in a circuit to photons traveling through the air. Engineers view antennas as filters in both space and frequency, since antennas are only looking in certain angular regions over certain bandwidths. No antenna is perfectly isotropic, and no antenna works over all frequencies. Thus, the proper selection of an antenna for each application is very important.

Welcome to the Antenna DIY Blog

Welcome to the Antenna DIY Blog!

With the popularization of 802.11, HDTV, GPS, Bluetooth, RFID, and of course cellphones there are a lot of signals in the air these days. This blog will apply a do-it-yourself perspective to a topic that many find confusing.

I'll post some designs and ideas that I hope are useful, as well as the best references to get more information.

John