11
votes
Accepted
Difference between antennas for Wi-Fi vs. ham repeaters
In order to use the same antenna design at different frequencies, "all you need to do" is scale all elements of the antenna proportionally to the difference in wavelength. For example, if you take a ...
- 25k
6
votes
Accepted
Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?
You can make a first order approximation by using typical WiFi ranges in combination with two free space path loss calculations.
802.11b/g has a typical indoor range of 150 feet. By calculating the ...
- 18.6k
6
votes
Yagi vs Parabolic Dish for 2.4GHz Campus Wifi from 1,800ft away?
Depends on the particular Yagi or dish. Look for a published gain. Beware of low-quality manufacturers that publish erroneous data. Higher gain will correlate with higher probability of working. Point-...
- 52.5k
6
votes
Where can I find a very long distance Wifi antenna with a range of 50-100 km? Or is it a DIY project?
As the comments on the question suggest, there are regulatory concerns that may be relevant. But those are dependent on jurisdiction, so let's not get into that. A separate question, tagged with your ...
- 52.5k
5
votes
Beamwidth of omni-directional antenna with gain
According to Kraus$^1$, the directivity of an antenna with a given beamwidth can be approximated by:
$$D\approx\frac{4\pi}{\theta_{HP} \phi_{HP}}$$
where $\theta_{HP}$ and $\phi_{HP}$ are the half-...
- 7,912
5
votes
Accepted
Is there a practical way for hams to participate in cellular-related technology advances?
Are there any cellular bands that are close enough to amateur allocation for off-the-shelf cellular modems/filters/antennas to work?
Yep, thanks to the fact that what is a GSM band in Europe is the ...
- 17.4k
5
votes
Accepted
Transmission power of Apple Wi-Fi antennas (EMF and health)
Maximum permissible power output for Part 15 operation is 1W; Apple devices are known to use up to that limit.
e.g. https://fccid.io/BCGA2589/Test-Report/WLAN-OFDMA-Test-Report-1-5691887.pdf
The above ...
- 166
5
votes
How does tuning in 2.4 GHz Wifi radios work?
Nobody can tell you how your specific 2.4 GHz Wifi chip works, as we don't know it, let alone its internals. However, reasonable assumptions can be made:
WLAN of the IEEE802.11a variant has been ...
- 17.4k
4
votes
How does Wi-Fi antenna work?
The antenna in photo below is the 1st antenna of the question.
It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if ...
- 389
4
votes
How does Wi-Fi antenna work?
This is the 2nd antenna of the question (screenshot from video linked in the question).
Below are simulation results of an antenna similar to the one above. Although simulated antenna is not for ...
- 389
4
votes
How does Wi-Fi antenna work?
Between lengths of infinitesimal and one wavelength, the lobes in the radiation pattern become narrower. Here's a picture from antenna-theory.com:
Notice how for the 1-wavelength antenna, the lobes ...
- 52.5k
4
votes
What is the optimal antenna for a high altitude weather balloon?
I've never launched a balloon, but I'd guess gravity would keep the antenna oriented vertically so circular polarization is unnecessary weight. If you did want circular polarization, put it on the ...
- 52.5k
4
votes
What is the optimal antenna for a high altitude weather balloon?
2.4 GHz is most definitely not the way to go, unless you very much know what you're doing.
The free-space path loss over a fixed distance increases with the square of your frequency.
Whilst one ...
- 17.4k
4
votes
4G extension cable and antenna height?
If you elevate the antenna, you will absolutely increase your range, provided that the feedline loss is low enough.
The coax should be mostly vertical, or the coax loss could offset the height gain. ...
- 8,174
4
votes
Is there an 802.11 Wi-Fi module that allows direct access to the PHY layer
"Wi-Fi" is a trademark referring to the 802.11 family and has layer2 definitionally baked in.
If you want to roll your own layer2, you specifically do NOT want WiFi or 802.11 family chips.
...
- 4,658
4
votes
miniature parabolic antenna
From this equation, for a passive antenna of 15 x 20 cm, you would expect a gain of under 14 dBi.
$$ A_e = 0.15 * 0.2 = {G\lambda^2\over{4\pi}}$$
I don't recommend trying to make a reflector antenna ...
- 12.2k
3
votes
Wifi inside a rocket
The biggest issue between stages is that wifi doesn't penetrate metal well. Engine bells and plumbing are generally metal, even if tanks and exterior airframe skin aren't. Since cables are highly ...
- 4,145
3
votes
My radio in the garage is temporarily shutting down the wifi when I key up
Sounds like the router is getting front end overload.
Either your OCF dipole is too close to the router, or you are getting common mode current on the coax and it is radiating along the coax.
A balun ...
- 6,960
3
votes
Making WiFi access point range shorter on purpose
For a device to register with the access point, it must receive a transmit signal from the access point (AP). This largely consists of the AP transmitting its SSID so that it can be detected by the ...
- 18.6k
3
votes
Will very close proximity to electrical wires affect radio signals?
Will the electrical wires seriously affect wireless signal performance?
Yes, electrical conductors within the near field of an antenna will actually become part of the antenna and change its ...
- 17.4k
3
votes
Accepted
Amateur Radio Long Distance Data Communication
The most accessible way to get digital communication at that speed is WiFi. You could use unmodified consumer equipment, or getting a ham license would allow you to use frequencies not usually ...
- 52.5k
3
votes
Is it possible to boost WIFI signal?
It Is quite possibly illegal. Actually amplifying your router or extender wireless signal to extend its reach runs the risk of being illegal in many countries. Any wireless device sold in a country ...
- 283
3
votes
Antenna reciprocity how does an antenna increase receiving range?
So to start off: I (an electrical engineer who had to take classes on that stuff) regularly get sad when I read the packaging of Wifi equipment, because the marketing speech on that is so wrong it ...
- 17.4k
3
votes
Accepted
SMA Connector Impedance
Lots of questions here, let me try to cover them point by point.
A monopole is half of an antenna. A real antenna is a dipole. The monopole needs a "ground plane" to replace the missing ...
- 6,960
3
votes
Accepted
Long Distance antenna feedline for UHF/2.5GHz signal
If you can incorporate a strong, thin coax into the tow cable, you could use it to connect directly from radio to radio.
Wifi radios expect up to 80 dB of path loss, even 100 dB at lower speeds (+20 ...
- 12.2k
2
votes
Amateur Radio Long Distance Data Communication
In a word, No. For 1Mb/s you'd need a line-of-sight connection, so over a 180-mile path, you would need multiple hops. The alternative would be satellite communications but the ham satellites have ...
- 959
2
votes
Accepted
Understand Radio Pattern of a WIFI antenna
The numbers arranged vertically are decibels. They tell you the relative radiant intensity in each direction. For example if in one particular direction you read 0 on that scale, and in another ...
- 52.5k
2
votes
Wireless signal strength explanation needed
A Wi-Fi transmitter, like a lightbulb, throws out photons in a lot of directions. Only some of them will be captured by the receiver. Most will go elsewhere, eventually being absorbed by walls, ...
- 52.5k
2
votes
Accepted
Wireless signal strength explanation needed
I can think of a few reasons why your WiFi signal strength is 45 dB down from what your router's documentation suggests.
Your phone and antenna aren't calibrated. Your app makes signal strength ...
- 9,320
2
votes
Connecting Directional Antenna To Two Antenna Ports on NIC
Wireless NICs and APs have multiple antennas for MIMO. This means the device dynamically determines the coefficients for each antenna to combine them in the best way.
Often that means phasing the ...
- 52.5k
Only top scored, non community-wiki answers of a minimum length are eligible