Embedded Systems Conference
Breaking News
Comments
Newest First | Oldest First | Threaded View
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.

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.

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



Radio
LATEST ARCHIVED BROADCAST
As data rates begin to move beyond 25 Gbps channels, new problems arise. Getting to 50 Gbps channels might not be possible with the traditional NRZ (2-level) signaling. PAM4 lets data rates double with only a small increase in channel bandwidth by sending two bits per symbol. But, it brings new measurement and analysis problems. Signal integrity sage Ransom Stephens will explain how PAM4 differs from NRZ and what to expect in design, measurement, and signal analysis.

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Most Recent Comments
VicVat
 
jnissen
 
M_Alex_Nugent
 
traneus
 
David Ashton
 
perl_geek
 
Max The Magnificent
 
perl_geek
 
perl_geek
Like Us on Facebook
Special Video Section
The LTC®6363 is a low power, low noise, fully differential ...
Vincent Ching, applications engineer at Avago Technologies, ...
The LT®6375 is a unity-gain difference amplifier which ...
The LTC®4015 is a complete synchronous buck controller/ ...
10:35
The LTC®2983 measures a wide variety of temperature sensors ...
The LTC®3886 is a dual PolyPhase DC/DC synchronous ...
The LTC®2348-18 is an 18-bit, low noise 8-channel ...
The LT®3042 is a high performance low dropout linear ...
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 ...