PCB trace antenna connection from Impedance matching IC

[Kick]

hiii all,
Is it a good routing to PCB trace antenna from a Impedance matching IC??

 

[lhademmor]

Nothat line are to long and have several corners close to the antenna. Try rearrange or maybe mirror the antenna to clean up.

 

[Kick]

how about this design?

 

[FvM]

Your question is missing many necessary informations:

- what's the output impedance of the "impedance matching IC"? (Is it a ceramic chip balun?)

- what's the actual antenna input terminal and designed impedance?

- are there more PCB layers not shown in the screendump or just top and bottom?

To me it looks like an inverted F antenna with missing ground connection.

 

[Kick]

thanks for your reply.

Actually first time I am working with a antenna in PCB designing. Can u explain what are things should I care while routing a PCB trace antenna??only things I know is Ground plane should not be there under the antenna and Impedance should be 50 ohm. But I don't know how to calculate impedance of antenna?

 

[FvM]

It's most easy to refer to predesigned PCB antennas from RF chip manufacturer application notes, e.g. Texas Instruments.

It's not so easy to "calcucate" the impedance of an antenna. There are basic antenna types like λ/2 dipole or λ/4 monopole with known impedance. But the prerequisites are often not met. E.g. a monpole like your antenna is designed with the assumption of an infinite ground plane which is rarely feasible in a mobile device.

In practice you can determine the antenna parameters in EM simulation or measure it empirically with a network analysator.

For your design, I was primarly asking about the intended antenna type because it's not clear from the picture.

 

[lhademmor]

As FvM says it looks like you are missing a GND connection at the right side some where.

 

[Kick]

hii,

But in some circuit I could find antenna connection with only one connection(feed line).

 

[FvM]

Yes, in case of a straight or bended monopole, or a meander antenna. But your antenna looks like an inverted-F, an electrical small (< λ/4) monopole with built-in impedance transformation. It needs a ground connection.

Where did you copy the antenna, how was it connected in the original design?

 

[Kick]

actually I got it from an eagle design,here I am using altium designer. Problem is when connecting the ground to antenna is showing DRC error because 2 signals connecting to same area(feed and gnd)

 

[FvM]

So you decided to change the antenna instead of solving the layout tool problem?

My solution in this case is a kind of "network connector", placing copper on a non-electrical layer that is added to the respective artwork layer in postprocess.

Or accept that the antenna output is logically connected to ground.

There may be other options to connect networks with Altium Designer.