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EM issues in Smart Antennas

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svarun

svarun

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Hi all,

I have been asked to come up with a research proposal on Smart Antennas (which everyone wants to do these days). Mostly yhis field belongs to Signal Processing. Being an EM guy, I want to look at what scope exists for EM studies in Smart Antenna Systems. Can any of you help me in listing out the possible EM related issues in Smart Antennas ?

One obvious issue would be reduction of mutual coupling. Any other suggestion ?

Thanks a lot.

-svarun
 

What about the Mean Effective Gain (MEG)? This paramters seem very crucial when multiple antennas are placed near each other. I think the cross-polarisation of the antennas play an important role on the value of this parameter.
 

yes, I think the observation of coupling effects could be
a good thema.
In Signal Processing Approach, the coupling effects are
normally neglected. So, in reality, these effects can change
the beam maximum and the zeros.
In MIMO system (as advanced study for smart antennas),
this problem has attracted more attention.
So, you can combine some numerical methods in
electromagnetics with some signal processing stuff.

regards
 

sassyboy said:
What about the Mean Effective Gain (MEG)? This paramters seem very crucial when multiple antennas are placed near each other. I think the cross-polarisation of the antennas play an important role on the value of this parameter.
Click to expand...

sassyboy,

Can you please let me know what exactly do yu mean by mean effective gain ? Any reference you can give in this regard will also be very useful.

-svarun
 

mudrik


In Signal Processing Approach, the coupling effects are
normally neglected. So, in reality, these effects can change
the beam maximum and the zeros.
In MIMO system (as advanced study for smart antennas),
this problem has attracted more attention.
So, you can combine some numerical methods in
electromagnetics with some signal processing stuff.





i was shocked after reading your post "EM and DSP are interrelated".could you please throw some more light on it.so,i will grab it
 

electronics_kumar said:
i was shocked after reading your post "EM and DSP are interrelated".could you please throw some more light on it.so,i will grab it
Click to expand...

There is no need to be shocked. They are not so much interrelated. DSP assumes antennas are ideal point sources without any mutual coupling betwen them. (Mutual coupling refers to appearance of voltage on adjacent antenna elements when a single elelment is activated). When this is present compensation needs to be done to obtain the correct weights for the antenna inputs for a particular beam direction. All we are trying to do is to calculate the mutual coupling between antennas from EM methods and incorporate it in the DSP algorithms.

-svarun
 

svarun said:
sassyboy,

Can you please let me know what exactly do yu mean by mean effective gain ? Any reference you can give in this regard will also be very useful.

-svarun
Click to expand...

Hi, there! Hmm.... I have not seen the MEG parameter used in describing Smart Antenna system. Therefore this parameter may not be related after all. But I would like to give you the following references and perhaps you could tell me if it's any good.

References:

1. **broken link removed**
2. **broken link removed**

There are many more, but these two I enjoy reading the most. Check their references to find out more relevant papers. It is a hot topic when diversity and correlation are involved in the antenna discussion.
 

    svarun

    svarun

    Points: 2
    Helpful Answer Positive Rating
The human tries to make something better (I hope so).
Scattering and multipaths bring some problems in telecommunication.
However, in MIMO system, we make use these phenomena for
our profit.
Antenna coupling on the other side can reduce the performance of
MIMO systems.
Is there any way out to make use this phenomenon (coupling effects) ?

regards
 

mudrik said:
Is there any way out to make use this phenomenon (coupling effects) ?
regards
Click to expand...

Hmm.... sounds interesting. I was thinking something like how to use noise for our benefit in circuits. It is kind of similar in the sense how to use a harmful effect to our advantage.

BTW regarding multipath effects, we have not been able to fully exploit it. In an AWGN the Bit Error Probability goes as inverse exponential of SNR. In multipath fading whatever diversity you emply, the BER goes down as inverse SNR power some integer and it can never be as good as AWGN( no multipath).

My two paise worth (indian currency, 48 of which is equivalent to 1 cent :( :cry:).

-svarun
 

Polarization mismatch can seriously hamper system performance. But in MIMO polarization diversity can be used to increase system capacity. It might be interesting to study the combined effects of polarization diversity and spatial diversity on a MIMO system. Hope this helps

regards
Abhishek
 

mudrik said:
Antenna coupling on the other side can reduce the performance of
MIMO systems.
Click to expand...
As far as I know, mutual coupling between the antennas is a key point in MIMO systems by increasing the channel capacity, which is used as an adventage. As some people outlined above using multiple antennas avoids multi path fading, i.e. superposition avoids fading drop-offs at certain locations.

As a suggestion for Smart antennas I would recommend you to see the Cisco corp. supported projects. They are interested in smart antennas very much and support Smart antenna projects worldwide.

edit: it might be also useful to search for smart antennas in EMT based magazines and journals like antennas and propagation magazine, microwave technology and techniques, transactions on antennas and propagatin... to see what is hot and what is not! :D
 

there are lot of papers available
eg: " a comprehensive performance study of circular and hexagonal array geometrics in the LMS algorithmn for Smart Antenna Applications" by Gozasht, Dadashazadeh and Nikmehr in PIER online

in general mutual coupling effects can be reduced by
1) the proper spacing of antenna elements -- in some cases it is said λ/2 and in the above paper mentioned it is taken as λ.
2)The algorithms like LMS, CMA are useful
 

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