Printed Circuit Board antenna / symetrical radiation pattern

[jabidof]

circuit board antenna

Hello everybody,

Does anybody already designed a PCB antenna that has a radiation pattern that is symmetrical in the XY plane.

In other words, when the antenna lays on the floor it'll radiate with the same gain in the polar coordinates r-θ-φ whatever the value of φ.

The λ/4 monopole perpendicular to an infinite ground plane has such a radiation pattern. I'd like to avoid having a (big) z-dimension.

Any hint?

 

[jabidof]

pc board antenna

Anyone?
Maybe description is not clear enough
Just let me know

 

[FvM]

antenna radiation

As a confusing point, φ is designating the elevation angle in spherical coordinates. Polar coordinates are two-dimensional and have angle Θ only. Thus you may want to clarify your specification.

Regarding the term symmetrical, there are different kinds of symmetry. I understand, that you want to achieve a circular symmetry in the horizontal plane. I think, with low vertical extension, circular polarization is the only way. Two orthogonal λ/2 dipoles, fed by a +/-45° phase shift network can do.

 

[jabidof]

pc board antennas

Yes, FvM, you're right about the elevation angle mistake i've made.

Could you detail a little more the antenna design you're proposing? Maybe you have some reference book or scientific article?

Thanks for your help

 

[FvM]

printed antenna pattern

Circular polarized antennas are often used for UHF RFID systems. They are discussed in some antenna design text books, as far as I remember. Achieving circular polarization by phase shifted feed is a basic RF concept, I guess you'll find many references in the internet. Unfortunately I have no particular link at hand.

 

[jabidof]

circuit board antenna

Ok, I found many info already. Thanks!

Got another topic to discuss. The chip I use outputs 2 differential signals (180° phase shift). Do you have any idea of how to use that specification in an optimal way to feed an antenna having circular polarization?

I believe we could obtain signals in quadrature by phase-shifting 1 output by 90° using a segment of microstrip but maybe something more elegant could be done based on the "natural" differential signals?

Thanks for any inputs on that issue.

 

[jabidof]

symetrical

Anyone could tell me if the question is meaningless?