-1
\$\begingroup\$

I want to know how this part (matching network) is designed. Can I use simpler design with minimum components? It is an SYN470R.

enter image description here

\$\endgroup\$
7
  • 1
    \$\begingroup\$ Title: how to design antenna? Answer to that: use a piece of wire / conductor with length \$\lambda/4\$ where \$\lambda\$ is the wavelength of 315 MHz (so the antenna will be around 24 cm long). Yet in question you circle the antenna + matching network. Are you asking how that is designed? Answer: by experimentation and possibly using a network analyzer. Be more precise what you are asking. \$\endgroup\$ Oct 13, 2021 at 7:07
  • \$\begingroup\$ L1, L2, C1 and C2 impedance match the antenna (unidentified) to the impedance of the chip (unidentified). Too many things unidentified to properly and succinctly answer this question. \$\endgroup\$
    – Andy aka
    Oct 13, 2021 at 7:14
  • \$\begingroup\$ @Andyaka thank you for your answer and sorry for my mistake , i mean "matching network". \$\endgroup\$
    – yeganehhp
    Oct 13, 2021 at 7:21
  • \$\begingroup\$ @Bimpelrekkie thank you for your answer and sorry for my mistake , i mean "matching network". \$\endgroup\$
    – yeganehhp
    Oct 13, 2021 at 7:21
  • \$\begingroup\$ @Bimpelrekkie ok \$\endgroup\$
    – yeganehhp
    Oct 13, 2021 at 7:25

1 Answer 1

1
\$\begingroup\$

If you read the chip's data sheet you can find its input impedance at 315 MHz on page 14.

enter image description here

You can then model that as a 12 Ω resistor in series with a 3.12 pF capacitor. If you assume a quarter wave monopole antenna, it has an output impedance of 37.5 Ω + 23.8 pF in series. Then, model both and do a simulation: -

enter image description here

Then run an AC analysis and you get this: -

enter image description here

So, it's not quite perfect at 315 MHz but, it's not far off. The gain is ~4.4 dB (not too shabby). Maybe it could be tweaked to optimum (12 dB gain) and maybe, if you took into account PCB board capacitances, self-resonant frequencies of the inductors used, it might be better than 4.4 dB of gain.

But, it's also likely that an antenna formed as a PCB pattern is going to have different impedances than for an ideal quarter wave monopole hence, you'd have to do some digging around to find more appropriate values.

\$\endgroup\$

Not the answer you're looking for? Browse other questions tagged or ask your own question.