advertising issue with nrf51822 ceaa

RE: advertising issue with nrf51822 ceaa

RK — Fri, 08 Apr 2016 10:21:39 GMT

Yes with just a balun connected directly to the antenna, as long as the antenna is somewhere near 50 ohms, it'll work. The power and range will suffer the worse the antenna is matched but you should get something. So replace L1 with a 0 ohm resistor and remove the yellow wire and try that. Since the antenna is a chip antenna (if I'm reading it right) the impedence should be not bad as long as you mounted it sensibly and it ought to work ok.

RE: advertising issue with nrf51822 ceaa

hello_alberto_ — Fri, 08 Apr 2016 10:06:45 GMT

thanks! one more question. should the device be able to advertise just with a Balun (no pi-network and antenna)? i am not saying it should perfectly. does it at least advertise very weak?

RE: advertising issue with nrf51822 ceaa

RK — Thu, 07 Apr 2016 12:49:29 GMT

... and you two are now talking about entirely different things. embeddedmasters is trying to say you don't need a balun if you have a matching circuit, but he's talking about the discrete matching circuit on the nordic reference design which can be used instead of a balun. Whether you use a balun or the discrete matching circuit, you still need another matching circuit ( the pi network in this case) for the antenna.

RE: advertising issue with nrf51822 ceaa

hello_alberto_ — Thu, 07 Apr 2016 12:46:33 GMT

thank you for the reply. i understand balun would work without a pi network; however, i added a pi network to optimize to match 50 ohm impedance.

RE: advertising issue with nrf51822 ceaa

RK — Thu, 07 Apr 2016 12:46:33 GMT

Nordic has a reference circuit which uses the balun as well as the reference circuit which uses the discrete matching network I doubt he's using both, what's on the other side of the balun in this case is almost a direct connection to the nRF51. His problem is what comes AFTER the balun.

RE: advertising issue with nrf51822 ceaa

RK — Thu, 07 Apr 2016 12:44:03 GMT

It totally shorts the signal out - you have 0 ohms impedence and 100% signal reflection and you will get absolutely no output at all.

Again - where did you get that circuit from? That's not on any reference design I've ever seen published .. because it makes no sense.

The nrf51 reference circuit I know stops at the balun, ie A1 and B1. Where did you get the rest from? It's wrong.

RE: advertising issue with nrf51822 ceaa

hello_alberto_ — Thu, 07 Apr 2016 12:40:36 GMT

So, would it have zero(totally no) signal with that wire going to ground? or should it at least advertise very weakly?

RE: advertising issue with nrf51822 ceaa

embeddedmasters — Thu, 07 Apr 2016 12:39:26 GMT

Hello Alberto, Yes a direct path to GND prior to an Antenna will cause problems. A simple question to ask yourself is what would happen if you shorted your power supply to GND? Bad things... A PI filter should have a cap on each side of the inductor. I am also not understanding the reason for the Balun if you are using the Reference schematic? I might suggest you look at the reference schematic on the DK 51 which is shown below. I can't see what is on the other side of the balun but I have a hunch this is not needed. See the below schematic from the DK 51...

RE: advertising issue with nrf51822 ceaa

RK — Thu, 07 Apr 2016 12:25:41 GMT

And I note you've changed the circuit diagram from the one you originally posted to another one, but that still has the shorting wire in it and it still looks entirely wrong.

RE: advertising issue with nrf51822 ceaa

RK — Thu, 07 Apr 2016 12:24:30 GMT

Where did you get that circuit from? That extra wire just shunts the entire signal to ground, the antenna wouldn't see signal at all, that's not 50 ohms, it's zero.

So yes that would definitely be a problem.