Breaking News
Oldest First | Newest First | Threaded View
User Rank
re: Embedded antennas demystified
MWASEK   7/22/2008 9:59:39 AM
I am studying M Sc in elecrtrical engineering at BTH in Sweden. My course works have been completed and now I am trying to prepare my thesis proposal on Antenna technology. These information helps me a lot to think about my future research area in Antenna.Thanks. If possible then please send me the current research topics in this area which will help me lot to select my research topic. Email: Regards. Manik Wasek

User Rank
re: Embedded antennas demystified
green_is_now   4/26/2013 3:10:29 PM
10 db of loss = 90% efficiency throughput?? I thought this was a EE rag.

User Rank
re: Embedded antennas demystified
mike_m   5/7/2013 7:00:17 PM
It is not 10 db of signal loss it is 10 db of return loss, or RL, which the article is talking about. Return loss is the portion of a transmitted signal that cannot be absorbed by the load (the antenna in this case) and is reflected back to the source (transmitter). In this article 90% of the transmitted power is absorbed or transmitted by the antenna and a small 10% of the total power is reflected back to the source (the transmitter) due to the mismatch from a theoretical perfect 50+J0 load impedance. I won't get into waves reflecting from antenna back to the source and then back again to the antenna and then back to the source but suffice to say this is what happens in a mismatched system. RL is calculated as follows RL=20log((ZLoad-Zsystem)/(Zload+Zsystem)) where Zsystem is typically 50 ohms, the result is displayed as negative db numbers. Think of it in a way as to how far the load impedance is off of a theoretical/perfect 50+J0 ohms of impedance. With a perfect 50+J0 Z load you would then experience maximum power transfer where the source Z matches the Load Z and all the transmitted power is radiated by the antenna. In a typical perfectly matched antenna case the return loss would be an infinite - number but typically a RL figure of -30 db to -50 db is what a high acuracy power meter or network analyzer would provide for a system in near perfect impedance match. I say near perfect because in reality you will never experience a true 50+J0 load impedance.

Flash Poll
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Engineer's Bookshelf
Caleb Kraft

The Martian: A Delightful Exploration of Math, Mars & Feces
Caleb Kraft
To say that Andy Weir's The Martian is an exploration of math, Mars, and feces is a slight simplification. I doubt that the author would have any complaints, though.

The Engineering Life - Around the Web
Caleb Kraft

Surprise TOQ Teardown at EELive!
Caleb Kraft
Post a comment
This year, for EELive! I had a little surprise that I was quite eager to share. Qualcom had given us a TOQ smart watch in order to award someone a prize. We were given complete freedom to ...

Design Contests & Competitions
Caleb Kraft

Join The Balancing Act With April's Caption Contest
Caleb Kraft
Sometimes it can feel like you're really performing in the big tent when presenting your hardware. This month's caption contest exemplifies this wonderfully.

Engineering Investigations
Caleb Kraft

Frankenstein's Fix: The Winners Announced!
Caleb Kraft
The Frankenstein's Fix contest for the Tektronix Scope has finally officially come to an end. We had an incredibly amusing live chat earlier today to announce the winners. However, we ...

Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)