# Tag Info

11

IANAL, but based on my limited knowledge of US amateur radio regulations: Disable all encryption, as encrypted communications are not allowed within the amateur radio service. Yes, WEP counts as encryption, too. So does HTTPS, SSH or SMTP with STARTTLS. One of the few things you can allow is plain-text HTTP. Set the network SSID to your call sign. This ...

11

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 Yagi antenna designed for around 150 MHz, and scale all of the lengths in its design down by half, you will have a Yagi antenna good for 300 MHz. Of course, ...

10

This is a strange sort of question, as in reality the signal will go infinitely far (effectively) however you are really asking at what distance might a receiver be able to pick up the signal. In testing a 2.4GHz signal with a 100mW omni antenna, the furthest distance I could receive a signal with less than 5% retries (802.11b kit) was 2 miles with a 100mW ...

7

Assuming you are in the US (sorry if I'm wrong, but you didn't specify!), normal WiFi falls under Part 15 regulations which limit the radiated field strength, not the transmit power. This means that, assuming the transmitter is not underpowered, you cannot legally increase the range using directional antennas. Supposing you did so anyway, hooking up ...

6

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 location, would be appropriate. Let's focus just on the technical aspects. There are two concerns with getting a radio link over these distances: radio ...

6

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-to-point links of 1812 feet are easily accomplished, with a clear line of sight. I think you'll have 4 potential issues: Attenuation by the building will ...

6

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 difference in FSPL between 150 feet and 1812 feet, the approximate antenna gain requirement can be determined. Using an on-line FSPL calculator, we find 73 dB vs ...

5

I'm a math and computer science student, starting to mess around with using amplifiers and antennas to build long-range wifi hardware in my spare time. You're potentially breaking the law. In fact, I'm pretty sure you're breaking the law. WiFi operates in the ISM bands, which sets a very strong limit on how much power your device might send in any ...

5

I don't see why not. Of course, it's subject to the biggest problem with troposcatter: extremely high loss. Let's work out an example to see how bad this is. Let's say we want a link at a distance of 150km. Borrowing numbers from this question, let's further assume that we need -84dBm at the receiver to make the link work. And just for now, let's assume we ...

4

All the info you could ever want is being provided on this website..http://hsmm-mesh.org/ They are using WRT54G routers for ham band wifi usage. There is a great community for support and lots of documentation..Type "ham mesh net" into your favorite search engine and you will find many answers.

4

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 are skinnier than the 0.25-wavelength antenna. A 0.5-wavelength antenna is somewhere between the two. These patterns can be calculated from the current ...

4

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 WiFi 2.4 GHz (it is for ADS-B, 1.090 GHz), this simulation gives a general idea of characteristics of this type of antennas. The simulated antenna has two ...

4

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 its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is ...

4

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 could argue that an antenna with fixed area would at the same time increase its directivity with the square of frequency, this doesn't help you very much, because ...

4

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 ground station. It will mean a 3 dB penalty to your link budget. Free space path loss, with $r$ being the distance in meters, and $f$ the frequency in Hz, is: $$... 4 If you elevate the antenna, you will absolutely increase your range, provided that the feedline loss is low enough. The coax should be mostly vertical, or the coax loss could offset the height gain. To minimize loss, it should be as short as possible. That 30m cable is 3mm diameter, according to that Amazon listing; it is likely RG-174. RG-58 coax would ... 4 Are there any cellular bands that are close enough to amateur allocation for off-the-shelf cellular modems/filters/antennas to work? Yep, thanks to the fact that what is a GSM band in Europe is the American 33cm band. Does any relatively modern generation of cell technology have enough public datasheets for home/hobby use? Well, 2G and later standards ... 4 According to Kraus^1, the directivity of an antenna with a given beamwidth can be approximated by:$$D\approx\frac{4\pi}{\theta_{HP} \phi_{HP}}$$where \theta_{HP} and \phi_{HP} are the half-power beamwidths (in radians) in the azimuth and elevation planes. Simply put, this approximates the solid fraction of a sphere that is subtended by the antenna's ... 3 A parabolic antenna consists of two parts: the parabolic reflector a feed antenna at the reflector's focus The feed antenna is commonly a horn antenna, which can have a relatively wide bandwidth, depending on the particular design. You will want to check the antenna's specifications. If the feed antenna won't work at your desired frequency, then you can ... 3 The antenna feed is designed for 2.4 GHz, so performance at other frequencies will be not good (unmatched impedance, poor gain). The parabolic reflector is usable at other frequencies as long as the wavelength is not smaller than the grid spacing. You can calculate the gain of the reflector at other frequencies. 3 In 2006 the ARRL dropped its support for changing the rules to allow digital encryption. The rationale for their decision is that it was already legal. Their reasoning comes for the following FCC rule: Part 97 : Sec. 97.105 Control operator duties (a) The control operator must ensure the immediate proper operation of the station, regardless of the type of ... 3 Antennas don't have ranges. The maximum range of a link is determined by many factors in addition to the information you have about the antenna, among them: the power output of the transmitter (not the power rating of the antenna) the minimum usable signal of the receiver the strength of interfering signals the amount and type of obstacles (e.g. trees, ... 3 No. Most radio peripherals will not pass raw RF samples to or from the host computer, but only fully decoded packets. I'm not familiar with that particular card, but I'm sure if it had such capabilities people would be talking about it. (The so-called “RTL-SDR” TV tuner device does have this mode of operation, which is why it is so popular for cheap SDR ... 3 Your question can be answered by the Friis transmission equation. One way to write it is:$$ P_r=P_t+20\log _{10}\left({\frac {\lambda }{4\pi R}}\right)  Where: $P_r$ is the received power (in dBm) $P_t$ is the transmitted power $\lambda$ is the wavelength $R$ is the distance between the antennas, in the same units as wavelength Wavelength at 2.4GHz is ...

3

Trying to extend coverage in this fashion isn't worth doing. Even with highly directional antennas, most of the power transmitted doesn't end up in the receiver. Thus, your "repeater", which is really two antennas joined by coax, has very little power available to transmit. We can do some math. Let's assume that your buildings are 40m apart, and your ...

3

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 properties, and here, for the worse (since the small on-PCB antenna is designed for ISM band operation, whereas the combined antenna is not). At 2.4 GHz, wavelength ...

3

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 client device. If the client does not see the SSID, it often cannot detect the AP unless it is in active use by another client. The goal is therefore to ...

3

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 on the coax in the right place might help if it is common mode current.

3

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 reliable, it's worth having the weight to avoid dropouts when flight conditions add enough interference on top of the signal blockage to cut off your guidance at ...

2

It's unlikely that the transceiver at the fixed location will hear the relatively tiny signal from your phone 2km away well enough to establish a link. You need to have more power on both sides to make it work. Even then, you might need specialized, large antennas or dishes. Of course if there are no restrictions then you should be able to establish such ...

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