0
\$\begingroup\$

I'm right now working on a project involving 2 radio modules, a SIM800F and a LoRa1276-C1-868.

The modules are already certified under the radio equipment directive. In the case of the LoRa module it is certified using a wire antenna and helical antenna. In the case of the SIM800F I couldn't find it specified in any of the documents so I'm assuming it was tested without one, just using a breakout board (as shown in the pictures in the documents.)

In terms of connection this device is intended to have just 2 ports, one for GSM and an other for LoRa. The antenna should be selected according to the location requirements.

Is it possible to certify the device under RED without specifying the antennas used?

The people at the testing lab couldn't answer this very well, and it sounds strange that you would need to do testing for every antenna you could possibly connect to the device.

\$\endgroup\$
1
  • \$\begingroup\$ Btw in case of Semtech radios they usually have very good application notes explaining compliance to a certain standard. That's the first thing you should check! Lots of good reading here: semtech.com/products/wireless-rf/lora-core/sx1276. I only find one about FCC compliance at a glance, but there's probably one for EU/RED somewhere too. \$\endgroup\$ – Lundin May 12 at 11:50
4
\$\begingroup\$

First of all, for the license-free 868MHz radio band within EU, you need to meet the band requirements, which aren't covered by RED + technical standards. In most countries in the EU is 25mW ERP with tough 1% duty cycle requirements. EU has attempted to standardize this band through "Decision 2006/771/EC" also available for free, but national laws could override this one. Basically you need to know the allowed output power, the duty cycle if applicable and the channel spacing if applicable.

As for the RED directive contains a bunch of harmonized standards that may or may not apply depending on radio band. The relevant technical standard that you need to concern yourself with for 868MHz (all "sub-GHz") is EN/ETSI 300 220-2 "Short Range Devices (SRD) operating in the frequency range 25 MHz to 1 000 MHz" (v.3.1.1). This one is available for free and very technical.

Additionally, general EMC+ESD testing according to EN 301 489 and EN 61000-4-2 likely apply.

Your used modules need to state compliance both to the RED directive and at least to EN 300 220 in their EC Declaration of Conformity. In case they give you a list of antennas used in their 3rd party testing and you use those very antennas, you could argue that your product shouldn't have impact on radio and EMC requirements. It's important to realize that all the responsibility for this product falls on you, in case you are the party putting it on the market.

Similarly, if you do a 3rd party test with a bunch of other antennas, then you can say that your product only conforms to RED if those exact antennas are used. Then you push the responsibility onto the person connecting a different antenna there, but of course this also means paying up some big cash for a formal radio test.

Generally, if you use a different antenna than the one used during a 3rd party test, compliance turns questionable. As long as you use a zero gain omni-directional antenna tuned for the band, you probably haven't affected radio characteristics all that much and maybe you can refer to the documents of these modules in that case. Worst case you have a poorly adapted antenna and lose output power, which doesn't affect radio compliance. If you (or your customer) use directional antennas with gain, then that's naturally a whole different story.

The RED directive lists 3 ways to demonstrate compliance, called "Module A, B or C", where one possible way is self-testing through internal production control. So you don't have to perform 3rd party testing, but measuring ERP (effective radiated power), antenna directions etc is pretty much impossible to do outside an EMC lab. Other things like spurious out of band emissions you can fairly easily measure yourself with a spectrum analyser.

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

In the end it all leads to the basic question if the device might fail RED requirements or not.

Let‘s for example connect a satellite dish with e.g. 80dBi directivity to your RF port. Then you are likely to fail the +10dBm EIRP requirement because you litteraly beam too much power in one direction.

So if the user can connect any antenna, then you must specify restrictions on the antenna e.g. in the user manual. But if you deliver the device with a fixed antenna, then you can test this configuration (or claim module conformity).

\$\endgroup\$
3
  • \$\begingroup\$ i thought it may be that way, but when consulting about this some people told me that you normally test the whole thing as there may be interactions which could be problematic, would just considering the antenna gain count as due dillligence in terms of declaring conformity? would it be required for any antenna connected to be also ce marked? \$\endgroup\$ – diegogmx May 12 at 11:43
  • \$\begingroup\$ @diegogmx Output power isn't really specified by the RED Directive + standards but by the frequency band allocation, which in some cases comes with national regulations. Though of course radio testing measuring things like occupied bandwidth is heavily affected by your output power, so if you do a 3rd party test with a zero gain antenna, then put on something with gain later, it's hard to argue that your test is still valid. \$\endgroup\$ – Lundin May 12 at 11:47
  • \$\begingroup\$ @Lundin Point well taken \$\endgroup\$ – diegogmx May 12 at 12:21

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.