microstrip patch array simulation

wavenology said:

After looking at your structure, I think its either unmatched or poorly phased that caused the "awful" radiation, also, how do you know its awful? What do you expect of the radiation of such array?

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zorro said:

Hi aidin438,

I guess you want a maximum of radiation along the Z axis. In that case, the radiation of each patch is cancelled in that direction by its companion located beside it.

Z

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aidin438 said:

I want to have a directed beam in a special direction. in that pattern there are two lobes with 15 db gain but i want an antenna with a main beam and one big lobe.

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yeah! you're right. what should i do please?

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zorro said:

In theory, your design as is would give zero radiation in the z axis and two symmetrical beams with maxima in the xz plane. Right?


You must put in phase the patches that are now opposed in phase.
There are two possibilities:
a) feed all the patches from the same side (left or right) with equal lenght lines.
b) in you design as is, increase the length of the line that feeds one of the patches (of any couple) by a half wavelength.
Regards

Z

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aidin438 said:

how can i design a phased array microstrip in order to scan with the frequency? I mean that when you change the frequency the beam changes to another direction.

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zorro said:

Imagine a linear array with all the elements fed in phase with equal-length lines. The main beam points in the direction normal to the array.
Let f0 the frequency.
Now we do this:
increase the line that feeds the 2nd element by a length (call it L0) that introduces a phase lag of 360 degrees at f0,
increase the line that feeds the 3rd element by a length that introduces a phase lag of 2*360 degrees at f0 (i.e. 2*L0),
... and so on ...
At the frequency f0, all the elements are still in phase and tne beam has not changed.
But at a frequency greater than f0 the phase lag of the segment of length L0 (that has 360 deg at f0) introduces a greater phase lag, so the 2nd element is not longer in phase with the first. Along the array we have a progressive phase lag in the elements, that is the necessary condition for steereng the beam. More the frequency is increased and more the beam is steered.
Conversely, at frequencies lower than f0 the beam is steered in the other direction.

Is it clear?
Regards

Z

Click to expand...

zorro said:

Imagine a linear array with all the elements fed in phase with equal-length lines. The main beam points in the direction normal to the array.
Let f0 the frequency.
Now we do this:
increase the line that feeds the 2nd element by a length (call it L0) that introduces a phase lag of 360 degrees at f0,
increase the line that feeds the 3rd element by a length that introduces a phase lag of 2*360 degrees at f0 (i.e. 2*L0),
... and so on ...
At the frequency f0, all the elements are still in phase and tne beam has not changed.
But at a frequency greater than f0 the phase lag of the segment of length L0 (that has 360 deg at f0) introduces a greater phase lag, so the 2nd element is not longer in phase with the first. Along the array we have a progressive phase lag in the elements, that is the necessary condition for steereng the beam. More the frequency is increased and more the beam is steered.
Conversely, at frequencies lower than f0 the beam is steered in the other direction.

Is it clear?
Regards

Z

Click to expand...