Hi there,
currently I'am designing a circuit for nRF9160 inspired by Thingy:91.
About Thingy's antenna tuning (Thingy:91 User Guide page 16+17) I have some basic noob questions:
- Can I use other RF-Switches than the QM12038, like Skyworks SKY13418-485LF or QPC6082TR7?
Reason: Availabilty at Distributors.
- Are all RF-Switches drive RF Signals in both directions? are they bidirectional?
SKY13418-485LF has an ANT pin while QM12038 has an RFC pin which confuses me.
- Is the matching circuit for each Frequency range an impedance matching that reduces return losses?
Can I do the matching as follows?:
1.) Configure the two routing RF switches for an frequency range I like to do the matching for.
2.) Connect a MEGIQ Vector Network Analyser to RFC/ANT input of the first rf-swich (using a SWF connector)
3.) Use MEGIQ's Measurements to find passive tuning network for the desired frequency range. Impedance matching / reducing return losses?
4.) Switch to the next routing path and do the tuning for the next band and so on.
- Does the Thingy:91 antenna matching represent an aperture antenna tuning? or is this something total different?
- When does it make sense to use several switchable tuning networks and when not? Does it always improve antenna performance?
E.g. on nRF9160-DK there is only one tuning network for multibands, but long ground plane.
- Are the limited Thingy91 ground plane length + multiband application the main reason for the switchable tuning architecture?
Christof
