Q. Hi, If I had a wireless g router with a standard 2db antenna , with a laptop with a wireless g adapter, how far away could I go (in feet) staying in the line of sight of the router?
what about a 7db, 14db & 15db antennas?
Please advise, and a have a merry Christmas
what about a 7db, 14db & 15db antennas?
Please advise, and a have a merry Christmas
A. Imagine a light bulb. It radiates light evenly in all directions. That's an isotropic radiator. Antennas are passive devices. They don't amplify the signal. What they do is concentrate the signal power in a smaller volume. Imagine I put a mirror on one side of the light bulb. Now, one side of the mirror is dark and the other side is twice as light. We can say that the mirror is a 3 dBi antenna. 10^(3/10) = 2 Twice as much light on the lit side.
How far your antenna will reach depends on several factors. These include your input power, the cable loss between the source and your antenna, interference in the channel - meaning radio frequency (RF) noise in the atmosphere between your transmitting and receiving antennas, free space loss - which increases by the square of the distance between the transmit antenna and the receive antenna, signal to noise ratio of your source, receiver sensitivity, receive antenna gain, noise temperature of your receive system, and data rate [1]. 802.11g suffers from interference because it operates in the already crowded 2.4 GHz range. Other devices operating in this range include: microwave ovens, Bluetooth devices, baby monitors and (in the USA) digital cordless telephones [2].
For 802.11g, nominal bit speed is 54 Mb/s, but in low signal or noisy environments the transmission speed is slowed to allow more power per bit. For successful reception, the signal power per bit has to exceed the noise power per bit. By slowing the transmission speed, each bit is transmitted longer - giving more signal power per bit. 802.11g specifies DSSS-OFDM modes with payload data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mb/s as the signal to noise ratio decreases [3]. So, how far your antenna reaches is partly dependent on what data rate you're willing to accept.
Free space loss varies by the square of the range. See equation 5.13 in [1]. Expected range for 802.11g is 38 meters (124') indoors and up to 140 meters (459') outdoors in good RF conditions [4].
A 7 dBi antenna will give 5 dBi more than the standard 2 dBi. The math for the range is sqrt(10^(5/10)) = 1.8. The 7 dBi antenna will give you approximately 1.8 times the range of the 2 dBi.
Likewise for 14 dBi, sqrt(10^(12/10)) = 4. Approximately four times the range.
For 15 dBi, sqrt(10^(13/10)) = 4.5. Approximately four and one-half times the range.
There is a handy Radio Link Budget Calculator available online at [5]. Example numbers for the setup with the wireless router and laptop, use:
Frequency GHz: 2.4
Tx antenna diameter: .06
Tx antenna efficiency: .65 (the default)
Tx power at feed (W): .3
Range (km): .140
Bandwidth: 22000000 (the default)
Rx antenna diameter: .01
Rx antenna efficiency: 0.65 (the default)
Rx system noise temp (degrees K): 440 (the default)
Receiver sensitivity -80 (this is a pretty good wireless card)
You'll get -69 dBm at the receiver - about correct for most wireless cards.
These estimates are consistent with my experience. FWIW, I attached the antenna in [6] to my laptop via a short pigtail. Using this setup, I am able to pick up 802.11b/g access points up to about 1/2 mile away.
Also, you might consider switching to 802.11n. 802.11n uses multi-input, multi-output (MIMO) technology. Basically it shifts phase of several small antennas to digitally "steer" the waveform to improve transmission and receive range [7].
If this doesn't help, e-mail me and I can point you to more info on computing link budgets [8][9].
How far your antenna will reach depends on several factors. These include your input power, the cable loss between the source and your antenna, interference in the channel - meaning radio frequency (RF) noise in the atmosphere between your transmitting and receiving antennas, free space loss - which increases by the square of the distance between the transmit antenna and the receive antenna, signal to noise ratio of your source, receiver sensitivity, receive antenna gain, noise temperature of your receive system, and data rate [1]. 802.11g suffers from interference because it operates in the already crowded 2.4 GHz range. Other devices operating in this range include: microwave ovens, Bluetooth devices, baby monitors and (in the USA) digital cordless telephones [2].
For 802.11g, nominal bit speed is 54 Mb/s, but in low signal or noisy environments the transmission speed is slowed to allow more power per bit. For successful reception, the signal power per bit has to exceed the noise power per bit. By slowing the transmission speed, each bit is transmitted longer - giving more signal power per bit. 802.11g specifies DSSS-OFDM modes with payload data rates of 6, 9, 12, 18, 24, 36, 48, and 54 Mb/s as the signal to noise ratio decreases [3]. So, how far your antenna reaches is partly dependent on what data rate you're willing to accept.
Free space loss varies by the square of the range. See equation 5.13 in [1]. Expected range for 802.11g is 38 meters (124') indoors and up to 140 meters (459') outdoors in good RF conditions [4].
A 7 dBi antenna will give 5 dBi more than the standard 2 dBi. The math for the range is sqrt(10^(5/10)) = 1.8. The 7 dBi antenna will give you approximately 1.8 times the range of the 2 dBi.
Likewise for 14 dBi, sqrt(10^(12/10)) = 4. Approximately four times the range.
For 15 dBi, sqrt(10^(13/10)) = 4.5. Approximately four and one-half times the range.
There is a handy Radio Link Budget Calculator available online at [5]. Example numbers for the setup with the wireless router and laptop, use:
Frequency GHz: 2.4
Tx antenna diameter: .06
Tx antenna efficiency: .65 (the default)
Tx power at feed (W): .3
Range (km): .140
Bandwidth: 22000000 (the default)
Rx antenna diameter: .01
Rx antenna efficiency: 0.65 (the default)
Rx system noise temp (degrees K): 440 (the default)
Receiver sensitivity -80 (this is a pretty good wireless card)
You'll get -69 dBm at the receiver - about correct for most wireless cards.
These estimates are consistent with my experience. FWIW, I attached the antenna in [6] to my laptop via a short pigtail. Using this setup, I am able to pick up 802.11b/g access points up to about 1/2 mile away.
Also, you might consider switching to 802.11n. 802.11n uses multi-input, multi-output (MIMO) technology. Basically it shifts phase of several small antennas to digitally "steer" the waveform to improve transmission and receive range [7].
If this doesn't help, e-mail me and I can point you to more info on computing link budgets [8][9].
computer wifi slowdown?
Q. I have a laptop, a hp dv6105us,and unil recently, it was constantly running 54mbps. now, i'm lucky to get 11. do i need to get a new card?
A. This probably isn't a hardware problem; you don't need a new card.
The simplest reason for this would be noise or interference. (Baby monitors and 2.4GHz cordless phones sometimes cause this.) Rebooting your wireless access point might get it to try a different channel.
Another possibility is that either the card or the AP is using 802.11b instead of 802.11g -- that would be a configuration problem. If you only see speeds of 2, 5.5 and 11, then this might be the problem.
The simplest reason for this would be noise or interference. (Baby monitors and 2.4GHz cordless phones sometimes cause this.) Rebooting your wireless access point might get it to try a different channel.
Another possibility is that either the card or the AP is using 802.11b instead of 802.11g -- that would be a configuration problem. If you only see speeds of 2, 5.5 and 11, then this might be the problem.
networking?
Q. wireless networking protocol
A. Wireless Protocols
A protocol is a set of rules or agreed upon guidelines for communication. When communicating it is important to agree on how to do so. If one party speaks French and one German the communications will most likely fail. If they both agree on a single language communications will work.
On the Internet the set of communications protocols used is called TCP/IP. TCP/IP is actually a collection of various protocols that each have their own special funtion or purpose. These protocols have been established by international standards bodies and are used in almost all platforms and around the globe to ensure that all devices on the Internet can communicate successfully.
There are a variety of protocols currently in use for wireless networking. Arguably, the most prevalent is 802.11b. Equipment using 802.11b is comparitively inexpensive. The 802.11b wireless communication standard operates in the unregulated 2.4 Ghz frequency range. Unfortunately, so do many other devices such as cordless phones and baby monitors which can interfere with your wireless network traffic. The maximum speed for 802.11b communications is 11 mbps.
The newer 802.11g standard improves on 802.11b. It still uses the same crowded 2.4 Ghz shared by other common household wireless devices, but 802.11g is capable of transmission speeds up to 54 mbps. Equipment designed for 802.11g will still communicate with 802.11b equipment, however mixing the two standards is not generally recommended.
The 802.11a standard is in a whole different frequency range. By broadcasting in the 5 Ghz range 802.11a devices run into a lot less competition and interference from household devices. 802.11a is also capable of transmission speeds up to 54 mbps like the 802.11g standard, however 802.11 hardware is significantly more expensive.
Another well-known wireless standard is Bluetooth. Bluetooth devices trasnmit at relatively low power and have a range of only 30 feet or so. Bluetooth networks also use the unregulated 2.4 Ghz frequency range and are limited to a maximum of eight connected devices. The maximum transmission speed only goes to 1 mbps.
There are many other standards being developed and introduced in this exploding wireless networking field. You should do your homework and weigh out the benefits of any new protocols with the cost of the equipment for those protocols and choose the standard that works best for you.
A protocol is a set of rules or agreed upon guidelines for communication. When communicating it is important to agree on how to do so. If one party speaks French and one German the communications will most likely fail. If they both agree on a single language communications will work.
On the Internet the set of communications protocols used is called TCP/IP. TCP/IP is actually a collection of various protocols that each have their own special funtion or purpose. These protocols have been established by international standards bodies and are used in almost all platforms and around the globe to ensure that all devices on the Internet can communicate successfully.
There are a variety of protocols currently in use for wireless networking. Arguably, the most prevalent is 802.11b. Equipment using 802.11b is comparitively inexpensive. The 802.11b wireless communication standard operates in the unregulated 2.4 Ghz frequency range. Unfortunately, so do many other devices such as cordless phones and baby monitors which can interfere with your wireless network traffic. The maximum speed for 802.11b communications is 11 mbps.
The newer 802.11g standard improves on 802.11b. It still uses the same crowded 2.4 Ghz shared by other common household wireless devices, but 802.11g is capable of transmission speeds up to 54 mbps. Equipment designed for 802.11g will still communicate with 802.11b equipment, however mixing the two standards is not generally recommended.
The 802.11a standard is in a whole different frequency range. By broadcasting in the 5 Ghz range 802.11a devices run into a lot less competition and interference from household devices. 802.11a is also capable of transmission speeds up to 54 mbps like the 802.11g standard, however 802.11 hardware is significantly more expensive.
Another well-known wireless standard is Bluetooth. Bluetooth devices trasnmit at relatively low power and have a range of only 30 feet or so. Bluetooth networks also use the unregulated 2.4 Ghz frequency range and are limited to a maximum of eight connected devices. The maximum transmission speed only goes to 1 mbps.
There are many other standards being developed and introduced in this exploding wireless networking field. You should do your homework and weigh out the benefits of any new protocols with the cost of the equipment for those protocols and choose the standard that works best for you.
Can a Cisco Linksys E1200 router support an Xbox 360 wireless adapter?
Q. Im trying to connect to Xbox Live with my new wireless router, and im wondering if I buy an adapter, will it work? Im wondering, because I have looked at some videos of using a laptop and ethernet cable to connect to the wireless network, but my network and sharing center doesnt have the wireless network thing available. I know it sounds confusing, the wireless network is set up, but it says in the network connections section (where all the videos showed to go) all i have is local area connection and then it says wireless. In the videos, they have a local and a wireless one.
http://www.youtube.com/watch?v=NpBOnPB1jMU&feature=related
There is one of the videos I am talking about, there are several. Ask if you dont understand, i can explain it a bit better.
Thanks
http://www.youtube.com/watch?v=NpBOnPB1jMU&feature=related
There is one of the videos I am talking about, there are several. Ask if you dont understand, i can explain it a bit better.
Thanks
A. The E1200 is an entry level wireless N router with a 100Mb switch. This router runs 802.11n in the 2.4GHz frequency (~130Mbs) to be backward compatible with 802.11b/g. The downside is that if you have a mixed wireless client environment at home (Wii/Blackberry) - 802.11b/g, newer laptop with 802.11n) you will only ever get a max of 802.11g speeds. If you have any 802.11b only clients, your performance could be much less. If you have a mixed environment and really think you need 802.11n speeds then you should be looking at the E3000. This device has two separate radios (2.4GHz and 5GHz). You would then dedicate the 5GHz to your 802.11n and use the 2.4GHz for 802.11b/g connections. You also get a gigabit capable switch vs. 100Mb). Running 802.11n in the 2.4GHz frequency in theory is 130Mb/s and in the 5GHz frequency that is pushed to 300Mb/s. Keep in mind, that you will never get the advertised speeds, not even on b/g as the wireless protocol has a very large overhead. You are lucky if you actually see half of that speed. The 2.4GHz frequency does travel farther than 5GHz but with speed tradeoffs. 2.4GHz is also more susceptible to interference from the microwave, baby monitor, or anything else that runs in the 2.4GHz frequency.
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Title Post: Wireless G db antenna question?
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