planar anenna on metal sheet or on the PCB

I Want to know if a metal planer antenna is printed on a PCB SUBSTRACT without the ground plane, which difference of the performance will be produced, such as the efficiency, bandwidth, the input impedance? someone told me only the effeciency will be decreased, i am doubt about it, any one can give me a detailed reply on it

I'd like to know the same answer so if you have the answer, please reply.

The reason I don't use ground plane is to mimimize the amount of reflection when my receive and transmitt antennas are close together.

But no groud plane will reduce the gain I think.

hi,
with a ground plane suitably spaced from the planar antenna you achieve more Directivity and thus more gain. The efficiency increases but it is also possible to adjust the input impedance by adjusting the distance from the p.a.t.ch to the Ground plane, therefore increasing the efficiency further. The Bandwith is also affected.
Without the ground plane you are loosing much energy backwards!
regards

dch316:

What you said does make sense.

How many ways are there to adjust the distance between the ground and the patch? (I only know one: change the substrate thickness and material).

Thanks.

hi,
you're right, the distance is relative to the wavelength so changing the material (Er) is equivalent to change distance. The other way is changing the material thickness, but you should be aware that there are standard thicknesses. Remember also that changing the material implies changing the patch dimensions so that it is lambda/2 approximately.
Best regards

Planar antenna ( without a ground) and p atch antenna are quite different. It is hard to say which one is better. Usually, the p atch antenna has lower efficiency, higher directivity, and smaller bandwidth. However, a lot of effort has been put on the p atch antennas to improve their performance.

So what is the difference between planar and patch antenna ?

good topic,,are there any materials?

Hi, I do think that the antenna printed on PCB can provide better radiation performance in terms of matching and bandwidth because of less energy is confined in that region if we compare it with the patch antenna which only radiates along its two radiating edges.

Hi,

That depands what kind of antenna you are using.
If you are using a PIFA kind of antenna, it needs ground plane underneath because gruond plane is a part of the antenna. If you are using monopole, it does not need any ground plane, you may printed it on PCB.
From my cell phone antenna experience, it is better to put the antenna as high as possible above the PCB.

Any way, why not try?