Embedded Systems Conference
Breaking News
Comments
Oldest First | Newest First | Threaded View
MWASEK
User Rank
Author
re: Embedded antennas demystified
MWASEK   7/22/2008 9:59:39 AM
NO RATINGS
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: manikwasek@hotmail.com Regards. Manik Wasek

green_is_now
User Rank
Author
re: Embedded antennas demystified
green_is_now   4/26/2013 3:10:29 PM
NO RATINGS
10 db of loss = 90% efficiency throughput?? I thought this was a EE rag.

mike_m
User Rank
Author
re: Embedded antennas demystified
mike_m   5/7/2013 7:00:17 PM
NO RATINGS
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.



Radio
NEXT UPCOMING BROADCAST
In conjunction with unveiling of EE Times’ Silicon 60 list, journalist & Silicon 60 researcher Peter Clarke hosts a conversation on startups in the electronics industry. One of Silicon Valley's great contributions to the world has been the demonstration of how the application of entrepreneurship and venture capital to electronics and semiconductor hardware can create wealth with developments in semiconductors, displays, design automation, MEMS and across the breadth of hardware developments. But in recent years concerns have been raised that traditional venture capital has turned its back on hardware-related startups in favor of software and Internet applications and services. Panelists from incubators join Peter Clarke in debate.
Flash Poll
Top Comments of the Week
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Special Video Section
Chwan-Jye Foo (C.J Foo), product marketing manager for ...
The LT®3752/LT3752-1 are current mode PWM controllers ...
LED lighting is an important feature in today’s and future ...
Active balancing of series connected battery stacks exists ...
After a four-year absence, Infineon returns to Mobile World ...
A laptop’s 65-watt adapter can be made 6 times smaller and ...
An industry network should have device and data security at ...
The LTC2975 is a four-channel PMBus Power System Manager ...
In this video, a new high speed CMOS output comparator ...
The LT8640 is a 42V, 5A synchronous step-down regulator ...
The LTC2000 high-speed DAC has low noise and excellent ...
How do you protect the load and ensure output continues to ...
General-purpose DACs have applications in instrumentation, ...
Linear Technology demonstrates its latest measurement ...
10:29
Demos from Maxim Integrated at Electronica 2014 show ...
Bosch CEO Stefan Finkbeiner shows off latest combo and ...
STMicroelectronics demoed this simple gesture control ...
Keysight shows you what signals lurk in real-time at 510MHz ...
TE Connectivity's clear-plastic, full-size model car shows ...
Why culture makes Linear Tech a winner.