I am interested in getting into ham radio however one of my concerns is could a ham radio affect current wireless communications in my house. I am particularly concerned when it comes to WiFi signals. Where I would likely put a radio, I currently have my computer which connects via WiFi to my router.

I am concerned that if I set up a radio with an antenna on the roof above me, I could create interference for my already spotty WiFi signal. Is this a potential risk?

up vote 8 down vote accepted

Well, mostly no but yes it is possible for the antenna to have an effect.

No. I get more interference from wifi than interference to wifi.

In the computer adjacent to my ham station, I have had lockups but the network does not drop. It is not wifi related. I assume the lockups are from RF entering on a supposedly shielded cable like a USB mouse or keyboard cable. It happens rarely now that RF-blocking clip on toroids are on the shields of these cables.

Interference from a D-Link to the HF radio receiver was only partially reduced by wrapping the D-Link in Alumnium foil (except for the antenna, of course) and adding toroids to the ethernet and power lines. Routers can be noisy and some comparison shopping or additional internet questions may be in order.

Yes Any large metal object around your house, an antenna, a refrigerator, a metal table, your car in the garage, metal such as steel studs in the walls or floors ... will reflect the microwaves from your wifi. The level of wifi signal at a particular spot is affected by these reflections. This doesn't have anything to do with talking on the ham radio, we are just talking about microwave reflections off of passive metal objects.

As far as talking on the ham radio goes, the frequency for Wifi is 2.4Ghz or 5Ghz, which is quite different from the frequencies for most ham radio 1.8 - 432 Mhz. So they don't typically interfere. Also, interference temporarily slows down Wifi, it doesn't typically stop wifi unless somehow the router stops operating. The transmission protocol of Wifi immediately resends information that was missed due to any reason (weak signal, interference from neighbors' wifi, etc) without action by the user.

If you have ancient 1980s era 49 Mhz cordless phones or 49 Mhz baby monitors, get rid of those. Some amplified speakers -- like computer speakers -- may receive you when you talk. This does not indicate any fault, and is normal. It is the speakers that are the problem.

If you share your living situation with apartment neighbors or a home with a family or significant other, perception can be more important than fact. Perhaps strengthen the wifi first, and then worry about ham radio.

That being said, a variety of wifi routers and wifi antennas can be had for around 100 US dollars, and often less, that, by trial and error, might improve your existing signal levels. The typical $30 wifi router does not have a very powerful transmitter and you might pay attention to the output power (usually in milliwatts) if you upgrade it.

Some people build focused wifi antennas out of various food cans or flashlights to obtain a gain in signal. The construction of these wifi antennas is more of a do-it-yourself hobby among wifi hobbyists than necessitated by anything about ham radio.

  • As for power levels, you may want to consider my answer to a question over at SuperUser that mentions power levels specifically. Bottom line, you need quite a bit increase (on the order of tens of times) to really see much difference in terms of received signal strength. Consider that doubling the output power will, at best, give you +3 dB received signal strength (and likely considerably less accounting for multipath, reflection, attenuation and all those other funny things...). – Michael Kjörling Jan 20 '14 at 10:16
  • A US$20 Dlink DLR-601 has 18.7 dbm output power which I take as 75mW, whereas Amped Wireless has a router with 600mW -- so a 10x improvement in power is possible. Of course, increasing RF at the router does not increase the RX of the router to the TX at the computer or notebook. In such a case improvement to the antennas is probably a better approach. – Paul Jan 21 '14 at 4:24
  • Absolutely, I didn't mean to imply that it's worthless looking around (and I did actually upvote your answer). That said, one should be aware of the limitations of the approach as well, and I felt the linked answer describes those clearly. – Michael Kjörling Jan 21 '14 at 8:09

On which bands are you going to operate? I regularly operate on HF bands (160-10 meters) and never have any interference with the WiFi signal. Except if you operate on microwaves (e.g., 13 cm band, which overlaps with the frequency range used by 802.11b/g/n), I would not expect any interference on the WiFi.

However, there is something else to care about: ADSL/VDSL modems use frequencies in the HF range to modulate the internet data on a analog telephone line (which uses unshielded cables). If your output power is high enough, and the telephone line picks up enough signal, transmitting might prevent your Internet connection from working. My ADSL modem (actually I tried 3 different models... all of them had some issue) almost instantly loses connectivity if I operate on 3.5 MHz with more than 10-15 W of output power — but the telephone line has a very long cable inside the apartment, which might pick up a lot of RFI. I know other ham radio operators who don't have any problems with ADSL and have far more output power than me... so this depends a lot on your local setup. And if you're going to operate in VHF/UHF, I wouldn't expect any interference on ADSL. Cable modems (as they use shielded cables for transmission) will probably be less prone to interference with HF, but I don't have any direct experience with that.

Update: I've switched from ADSL to VDSL (to increase Internet bandwidth, fiber was unfortunately not possible), and moved the modem to the living room, around 10 meters farther from the transmitter than before. The telephone line now goes straight to the modem, and the line branch passing near the transmitter has been disconnected. As a result, even operating with the linear amplifier (~500 W output) on 3.5 MHz (or on any other RF band) does not affect the Internet connection in a significant way any more. I didn't look at the line quality parameters to see if there's any effect, but the connection stays up and the throughput doesn't seem to really change during transmission. I occasionally had disconnections while tuning the linear amplifier, but it only happens once in a while.

  • I'm working off of FiOS. So I don't think I should have trouble with cables. – Rob Rose Jan 20 '14 at 16:35
  • @Robert Rose I'm... This one may or may not be applicable to your case, but it would be a good idea to try to check if same applies to your neighbors as well. – AndrejaKo Jan 21 '14 at 18:53
  • Good point. That would be a good idea. – Rob Rose Jan 21 '14 at 19:59

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