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I want to make a pcb rf trace to use it as an antenna, for a bluetooth IC. I have already studied the basics of impedance matching and antenna tuning, smith chart and antenna clearance. The specific project is on my github, if anyone is interested: https://github.com/Basilisvirus/QFN48-nRF52811-Bluetooth-5.1-KiCad-and-Altium-Designer ,where i have a folder 'Antenna Design' with whatever i have studied.

My question is,

a) while i am tuning the antenna do i need to have the IC connected to the antenna?

b) while i do the impedance matching, do i need to have the IC connected to the antenna?

I will use a Vector Network Analyzer for tuning. I have a miniVNA Tiny available from a friend for that.

My guess is, probably not, but i wonder since my antenna has a ground connection [see image 2]. But i want to be sure, since the ICs i bought and the pcb printing are expensive for me, and i want to make it right on the first attempt.

I am right now building a pcb antenna without the chip footprint, image below:

Pcb antenna i am building

GND connection of the antenna [design found in github/antenna design folder]: Ground connection of the antenna

Thank you.

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  • \$\begingroup\$ You didn't mention how would you tune the antenna. \$\endgroup\$ – Marko Buršič Jul 21 '19 at 9:37
  • \$\begingroup\$ Thout it was for granted. Using a Vector Network Analyzer. I have a miniVNA Tiny available from a friend for that. I will add it to the question. \$\endgroup\$ – Basilisvirus Instrector Jul 21 '19 at 10:16
  • \$\begingroup\$ Quite expensive toy. I would rather use a ADALM-PLUTO SDR with a directional coupler for half the price, made by Analog Devices. \$\endgroup\$ – Marko Buršič Jul 21 '19 at 15:42
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The short answer no - we are trying to match the output impedance from the chip to the antenna for maximum power transfer (usually 50 ohms)

As you seem to be a beginner, I strongly recommend you to read this short guide, it's awesome. http://colinkarpfinger.com/blog/2010/the-dropouts-guide-to-antenna-design/

I've matched antennas with this guy and just an SMA connector :) https://signalhound.com/

Remember when you are performing your match, to encapsulate the antenna in its intended environment, and watch out for any metal from e.g. tables .. near/below the PCB

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  • \$\begingroup\$ Thanks, I remember starting from this guide, i will check it again, with my current knowledge, hope i got something more out of it. I remember you did not included the units [cm, inches] used to measure distances on this guide, i had trouble figuring that out back then. \$\endgroup\$ – Basilisvirus Instrector Jul 21 '19 at 10:11

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