Hi guys

I am familiar with a pi matching network for pcb antenna, but this one puzzled me. It use two caps (C34 and C23). Anyone seen this? As I have trouble matching this chip antenna to 50ohm.

chip antenna M620720 datasheet:
https://media.digikey.com/pdf/Data Sheets/Ethertronics/M620720.pdf

xDot Reference dev guide, p33, or see image below
http://www.multitech.com/documents/publications/manuals/s000645.pdf

 

Looks like a pi network of capacitors to me. Surprised you can't see it.

 

Looks like a pi network of capacitors to me. Surprised you can't see it.

Hmmm, that's new to me, I only come cross inductor and cap pi network, I will google it.

 

Hmmm, that's new to me, I only come cross inductor and cap pi network, I will google it.

Compute the reactance of the capacitors at 900 MHz., and tell me what that suggests to you. Notice the spaces for the resistor, inductor and one capacitor are marked OMIT. You are left with 3 capacitors in a pi configuration.

Also don't forget that if you sweep reactive components on a network analyzer that capacitors become inductors and inductors become capacitors as frequency increases and wavelength decreases into the centimeter and millimeter range and lumped components no longer adequately model the circuit.

Feynman's Volume II, chapter 23 has a nice discussion of what happens. Check it out.

http://www.feynmanlectures.caltech.edu/II_23.html

 

A true pi circuit is skinny. This one has a bandpass....for the speed of your data.

 

Compute the reactance of the capacitors at 900 MHz., and tell me what that suggests to you. Notice the spaces for the resistor, inductor and one capacitor are marked OMIT. You are left with 3 capacitors in a pi configuration.

Also don't forget that if you sweep reactive components on a network analyzer that capacitors become inductors and inductors become capacitors as frequency increases and wavelength decreases into the centimeter and millimeter range and lumped components no longer adequately model the circuit.

Feynman's Volume II, chapter 23 has a nice discussion of what happens. Check it out.

http://www.feynmanlectures.caltech.edu/II_23.html

and eventually we have the EMdrive. That Feynman was pretty smart.

 

and eventually we have the EMdrive. That Feynman was pretty smart.

He was also a pretty good locksmith and an admirer of go-go girls.