help for PCB antenna

[tomars]

I have added dipolo antenna to My PCB (Right)
I need 433 Mhz anetnna
There are also RFIS 13Mhz coil and Touch key on same PCB
Measuring with NanoVna I have the resonance at 300 MHz
I lost half a day to remove two turns at a time, and re measured, but the only thing that changed were decibel, the frequency changed a little.
Perhaps they affect other parts of the circuit too much ?
What can I try ?

[ Moderator action ] : Fixed typo on title

 

[tomars]

On this new antenna, resistor have opposite effect.

No res:

2K Res

New VS Old

 

[volker@muehlhaus]

The 2K resistor matching is not a universal trick, it is the outcome of calculations for one specific case. The universal trick is to add some loss, the value must be tweaked. If the antenna works without resistor, that's even better.

But let me repeat: results will change if you change the PCB size (length or width). For the upper antenna, the feed coax might have become an important part of radiating structure, because the PCB ground itself is too small there. Add a ferrite bead to block common mode current on the coax.

 

[tomars]

What influence does the thickness of the track have?

 

[volker@muehlhaus]

Track metal thickness (in z direction) has very little effect.

Track width for the radiator has some effect, but your dimensions look reasonable, so you can leave that. Track width for the short path to ground changes inductance of that path, so it changes matching.

The really relevant effect that you need to check now: how is the antenna detuned if you change PCB ground to the full PCB size from your initial post.

 

[kingcrediepcba]

I have added dipolo antenna to My PCB (Right)
I need 433 Mhz anetnna
There are also RFIS 13Mhz coil and Touch key on same PCB
Measuring with NanoVna I have the resonance at 300 MHz
I lost half a day to remove two turns at a time, and re measured, but the only thing that changed were decibel, the frequency changed a little.
Perhaps they affect other parts of the circuit too much ?
What can I try ?



View attachment 182333

View attachment 182334

[ Moderator action ] : Fixed typo on title

maybe this website is useful for you.

Design007 Magazine - Design007-Apr2023

 

[volker@muehlhaus]

Design007 Magazine - Design007-Apr2023

Wow, quite some misleading information and very few useful tips on antenna design, except "buy our EM simulation tools". Floating conductive radiator?? An antenna normally has 10 ohm impedance?? FEM is more suitable for antennas than FDTD? I guess you need to be Cadence to publish such an appnote.

 

[vfone]

"RF designers should take some tips from mixed-signal designers"

While ago, a mixed-signal designer gave me a tip: "never die Monday because you will have a bad week"

 

[kingcrediepcba]

Wow, quite some misleading information and very few useful tips on antenna design, except "buy our EM simulation tools". Floating conductive radiator?? An antenna normally has 10 ohm impedance?? FEM is more suitable for antennas than FDTD? I guess you need to be Cadence to publish such an appnote.

I saw it by accident and thought it maybe useful for you. In fact, I do not understand the design. I'm just a sales from King Credie Technology. I'm sorry for my inappropriate advice.