0
\$\begingroup\$

Pulse W3006 Chip Antenna Being Used

Impedance Matching Transmission Line Calculations

We are designing a custom PCB which uses a micro-controller with a single RF-out capable of doing 2.4G/5G/Bluetooth. This questions has 3 parts:

  1. Using the Chip Antenna on the physical Board
  2. Calculations for the transmission line between the chip antenna and Broadcomm Chip
  3. Using the single RF_out pin on the controller (Broadcomm WM-BAN-BM-13)

The antenna we are using is capable of doing both 2.4 Ghz and 5 Ghz, however the reference designs used with this particular chip only show a single feed line with a matching network going to it. Does this mean that the antenna can only operate in one of the two modes at a given time?

Additionally, the screenshot provided shows 2 different calculators used to design the attaching feed line. In the program to the left, it suggested a "Physical Length (L)" for the transmission line, from my understanding, this only pertains to the Frequency used for the feed signal and is used to help design the matching network with shunt capacitors and inductors if the line is less than that amount correct?

What would be the suggested way of using the calculated transmission line values and selecting the correct capacitor/inductor values for the desired length?

And lastly, if the BM chip only has 1 RF-out pin, how can a single transmission line for a single antenna be used for both 2.4 Ghz and 5 Ghz?

\$\endgroup\$
1
\$\begingroup\$

There is no reason why the chip and the antenna can't operate at both frequencies, it's just that the matching network becomes more complex as now you have two frequencies where you want a low insertion loss as opposed to just one. The advantage here is that the two frequencies are multiples of each other so the network may be a bit simpler. An antenna can be designed to work at more than one frequency (Log Periodic Antennas can cover an order of magnitude or more). Transmission lines aren't that picky about what frequency you send down them, a higher frequency will have more of a phase shift but that's it. The only time the length is a issue is when either you have several signals and they all need to arrive at the same time or when your matching network is made out of sections of different transmission lines. If using a discrete matching network, you're probably going to need more parts than you would have needed for a single operation frequency.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

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