[pic] can you determine what kind of this antenna

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bepsml

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dear all

i formed the antenna with no ground plane on bottom side, and I got good S11 after add a patch beside a feedline
can you determine what kind of this antenna, what a patch beside the feed can be called?

https://oi46.tinypic.com/2cyifpg.jpg

thank you
 

Hi bepsml,

I would say that it could be called a sort of modified fat monopole.
Is the length something less than a quarter wavelength?
Is the polarization predominantly vertical?

I think that the patch would act as an element that helps to match impedance.
I have curious to know how you came to this configuration.

Remember that not only s11 is of interest. Also radiation pattern, bandwidth and polarization.
Regards

Z
 

thank very much for reply Z

yes the feed length is less than a wavelength
i try to design an uwb antenna by a rectangular planar, after doing some modification, and finally got about 60% of fractional BW without forming a groundplane even adding that patch, migh this design classified as a valid antenna ?

by the way can i ask a ref which mention how a formulation to forming a ground plane, cz i stuck to get good BW with a ground on back side for my substrate with a fixed dimension
 

bepsml said:
yes the feed length is less than a wavelength
Click to expand...
How much (in wavelengths of the central frequency) is the side of the big square?

i try to design an uwb antenna by a rectangular planar, after doing some modification, and finally got about 60% of fractional BW without forming a groundplane even adding that patch,
Click to expand...
ok, but I'm intriged by the shape. How was it motivated?

...migh this design classified as a valid antenna ?
Click to expand...
Let me quote something appeared from an old book, and quoted in the preface of the book Phased Array Antenna Handbook (First Edition) by Mailloux:

Any pile of tin with a transmission line exciting it may be called an antenna. It is
evident on physical grounds that such a pile of tin does not make a good antenna,
and it is worthwhile to search for some distinguishing characteristics that can be
used to differentiate between an ordinary pile of tin and one that makes a good
antenna.

Regards

Z
 
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    bepsml

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excuse me "the side of the big square"?
ya from fc it solved, l feed, l shape = 0.18, 0.16 lambda, l patch (big square?) = 0.54 lamda
l shape = w feed

it just when i reviewing about CPW with no ground, then I adding that shape, and it worked

so according to achieved parameter like radiation pattern, BW etc, is the antenna can be said has a good antenna characteristic?
although I realize that is unusual design maybe
 
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bepsml said:
patch (big square?) = 0.54 lamda
Click to expand...
So it seems that it acts like a patch rather than a monopole, at least at central frequency.
Maybe the dominant mode changes with frequecy, and so the radiation characteristics (pattern, polarization).

bepsml said:
so according to achieved parameter like radiation pattern, BW etc, is the antenna can be said has a good antenna characteristic?
although I realize that is unusual design maybe
Click to expand...
Yes. Yet, usually the conceptual design has a rationale, and adjustmens are made by optimization or trial-and-error.
Regards

Z
 

OK great thank for your answer Z

maybe this tons of theory but can you give me a simple explanation how to determine that a shape act as monopole or patch please

once again I say thank before and after
 

As a rule of thumb:
The length of a monopole is about (a bit less than) 1/4 wavelength from ground plane to top.
The resonant side of a patch is about (a bit less than) 1/2 wavelength.
Regards

Z
 
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