Electronic – RF – changing a trace slightly from original design…

pcb-designRF

I am trying to make a new PCB for my self just for experimenting.

I found a document on TI website that suggests using a single chip 50Ohm Balun

That is fantastic as it saves anybody faffing about with calibrations and all that..

I have made a PCB before using a symmetrical PCB antenna with no balun and it worked fine in close range. TI always uses the Inverted F antenna as they say it performs the best..

I want to extend the range but i want to keep the PCB as compact as possible.
I found this SMD 2.4 Antenna

and I just wondered if i can connect it directly to the Balun?

The catch is that i need to change TI's recommend trace, add a 90degree bend to it.. otherwise the footprint is the same.

The original HOT wire is greyed out.. and all i want to do is put a kink into it.

enter image description here

I know RF is very temperamental to the slightest design change and I have no spectrum analysers or even experience to detect what this change could cause in the signal.

Can I .. just do this?

EDIT
I re read the pdf a few hundred times and realised it says this monopole antenna requires simple stripline matching on the PCB without the need for discrete components.

So am I correct in assuming that it is fine to put the bend in the place that I want?I do not really understand what that means.

EDIT 2

Do you think if i place it at 45 degrees.. it should be ok as its omnidirectional..

enter image description here

EDIT 3

THe mos logical way, as commented would be shifting it over. I think I will go with this..

enter image description here

Best Answer

My one concern was that the length of the transmission line from the chip to the antenna might be chosen to be some particular fraction of a wavelength for matching purposes. But the antenna datasheet shows high return loss at the operating frequency, indicating it simply appears as a 50 Ohm load at 2.4 GHz.

Given that, either of your designs is likely to work. The initial design (90-degree bend) could be improved by leaving the antenna pad at a 45 degree angle to the "southwest" and then making another 45-degree bend when it meets up with the existing track.

The second design (part placed at 45 degrees) should also be fine, but might be harder to work with if you were doing a very space-constrained design.

Another option would be to keep the antenna oriented at 90 degrees but move it to the right or left a few mm so that a straight track from IC would run straight to the appropriate pin.

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