Hello Andrew and thanks for these wonderful tutorials. When we solder the antenna to the sma connector pin you mention that we have to compensate such that the length of the sma pin and the first antenna section is exactly half a wavelength as specified. I thought the half wavelength section was measured exactly from were the outer shield stops on the sma connector. The reason I think this is because otherwise the length of the first half wavelength section could be considered to continue down through the coaxial cable, why start just because there is a pin there. The first few millimeters of the antenna that dissapears in under the shield of the sma connector could be considered the same as the coaxial cable that the connectors are eventually connected to. I am probably confused here really. Regards Peter
I still have the old Alpha card, the grey one. I have never since seen any other wifi card with -97 dB receiver sensitivity. However noise increases if transmit power is set too high for some reason, so I limited it to 64mW and it has exceptional range. It is my favorit dongle to bring along on camping.
Hi David yes that is how you calculate wavelength but it is not so cut and dry as the 5GHz band is big, 5.180 GHz to 5.825 GHz though some countries have different rules within this so it’s best to check where you live. The 2.4 GHz spectrum for wifi is a very small band. When designing the wavelength for this we aim for the middle of the band so it will work on all channels.
That being said, fast forward 6 years later and the 5 GHz (802.11a/h/j/n/ac/ax) band stretches from 4910 GHz (CH 186) to 5930 GHz (CH 7) putting the middle band frequency at 4970 GHz. I calculate the half length antenna for 5 GHz should be 30.18mm or can simply use 4900 GHz - 5900 GHz making the half length 27.77mm.
5 GHz is a lot bigger I am finding that you get a better performance if you aim for the top of the band 5.8 GHz. This may be because of interference for the heavily used 2.4Ghz spectrum. Thing is nobody is making antennas for 5GHz, (you tube is flooded with 2.4GHz antenna designs). The only exception to this is the RC community. So I welcome any feedback. Andrew
Nice vid - thanks for making it. Apologies if anyone else has already mentioned this, but it sounds like you connected this antenna "live" while the red-bar graph was being made. If so, did you notice that it began with a high (near 100% signal) gain? It makes me curious to see if the gain would increase again if you un-screwed the antenna a few turns, effectively lengthening it...?
Hi, it seems your antenna is suffering from imbalanced issue: it is an unbalanced fed by a coax which is balanced. A part of the current of the outer conductor of the coaw could flow out of the coax, is it why you take a very short coax (hardly not at all ? Have you considered the pottibility of having a tiny balun ?
10 лет назад
A 5 GHz collinear array will surely help users trying to avoid overcrowded 2.4 GHz band with dual band stock antennas with mediocre performance on both bands.
You can use a 90 degree SMA connector. The usual design for a dual band router is the 2.4 GHz band uses the external antenna and the 5.8 GHz band uses the internal PCB antenna. 5.8 GHz routers for household use were not designed to function over a distance but rather to add bandwidth. A dual band router is a hybrid legacy router as it should do 802.11 A,B,G,N. Unfortunately this is not the case one cheaper routers. Now in a true dual band router the load of traffic can be shared between two antennas. If you change the factory firmware you can assign which antenna does what. If you want greater distance then you go lower in frequency but sacrifice bandwidth. Example is 900 MHz Ethernet bridges can have a range of a mile or more depending on antenna and location. 2.4 GHz can travel up to a couple of city blocks and 5.8 GHz can travel across your home. Also keep in mind that you are dealing with microwaves and depending on your antenna and it's gain the ERP of microwaves can become a potential issue. 1/2 a watt at 5.8 GHz is enough to burn you.
Hmm, I must be missing something here. I calculate the half length antenna for 5GHz should be 29.98mm and the quarter length at 2.4GHz should be 31.23mm a difference of 1.25mm; I'm using lambda=c/f with c being the speed of light, f frequency and lambda wavelength. Is the above equation overly simplistic for antenna length calculation?
@David Griffin - Agreed,... @ timeline 5:37 - I get the same calculation for 2.4GHz as shown in the video,... and 5Ghz LAMBDA as a straight 60mm. Why this difference in the calculation ??? Is there a resonance 'material factor' for copper (generally considered) x0.95 ??? but why would this apply to the 5GHz and not the 2.4GHz calculation which appears correct. ???
Hi andrew. Thanks for the vids. I am going to try and make some ants for my RC stuff. i have 2.4Ghz for controlling my rc heli and 5.8Ghz for the video down link. I hope that a new ant on the 5.8 would be better tuned than the stock, as you have said it may just be ba standard 2.4 rubber duck. What is the software that you are using to show the results of your ant. At the moment i have no way to measure my results. Can you recommend a better type of 5.8Ghz ant to use the the heli which will be doing the video down link, i think that a normal rubber duck facing downward may get in the way as its stiff. Can i may some kind of 1/2 wave dipole? Thanks for your reply in advance
Hi Andrew. Your calculations seem to be a bit off. Please let us know how you calculate the wavelength, because I got different readings when divide the speed of light (299792458) by frequency.
***** Sorry guys but you need to look up short bottom fed dipole Wikipedia has a section on this. Wave length is not set in stone or there would be no need for antenna theory.Lots of things influence design and materials used etc
@@andrewmcneil Reverse engineering the calculations for the 'materials factor' (reactance offset) K = 0.862 for v/c !!! that's quite a difference from the standard 0.98 - 0.94 values indicated. Very interesting,... is there a LOOK-UP TABLE for the 'v' value of electric wave speed in a specific conductor diameter ( or circumference >> thinking skin effect )??? . Reverse calculating from K=v/c then,... 0.862 x 3x10^8 = v (MHz) - - then v = 258.6MHz for the velocity in the conductor versus AIR.
I have to say, your older video are some of the best as you show your face more...much more relatable
Hello Andrew and thanks for these wonderful tutorials.
When we solder the antenna to the sma connector pin you mention that we have to compensate such that the length of the
sma pin and the first antenna section is exactly half a wavelength as specified.
I thought the half wavelength section was measured exactly from were the outer shield stops on the sma connector.
The reason I think this is because otherwise the length of the first half wavelength section could be considered to continue down through the coaxial cable, why start just because there is a pin there.
The first few millimeters of the antenna that dissapears in under the shield of the sma connector could be considered
the same as the coaxial cable that the connectors are eventually connected to.
I am probably confused here really.
Regards
Peter
I still have the old Alpha card, the grey one. I have never since seen any other wifi card with -97 dB receiver sensitivity. However noise increases if transmit power is set too high for some reason, so I limited it to 64mW and it has exceptional range. It is my favorit dongle to bring along on camping.
Hi David yes that is how you calculate wavelength but it is not so cut and dry as the 5GHz band is big, 5.180 GHz to 5.825 GHz though some countries have different rules within this so it’s best to check where you live. The 2.4 GHz spectrum for wifi is a very small band. When designing the wavelength for this we aim for the middle of the band so it will work on all channels.
That being said, fast forward 6 years later and the 5 GHz (802.11a/h/j/n/ac/ax) band stretches from 4910 GHz (CH 186) to 5930 GHz (CH 7) putting the middle band frequency at 4970 GHz. I calculate the half length antenna for 5 GHz should be 30.18mm or can simply use 4900 GHz - 5900 GHz making the half length 27.77mm.
5 GHz is a lot bigger I am finding that you get a better performance if you aim for the top of the band 5.8 GHz. This may be because of interference for the heavily used 2.4Ghz spectrum. Thing is nobody is making antennas for 5GHz, (you tube is flooded with 2.4GHz antenna designs). The only exception to this is the RC community. So I welcome any feedback.
Andrew
Nice vid - thanks for making it. Apologies if anyone else has already mentioned this, but it sounds like you connected this antenna "live" while the red-bar graph was being made. If so, did you notice that it began with a high (near 100% signal) gain? It makes me curious to see if the gain would increase again if you un-screwed the antenna a few turns, effectively lengthening it...?
this is excellent information look forward to more vids!
loved it. look forward to seeing more!
Hi, it seems your antenna is suffering from imbalanced issue: it is an unbalanced fed by a coax which is balanced.
A part of the current of the outer conductor of the coaw could flow out of the coax, is it why you take a very short coax (hardly not at all ? Have you considered the pottibility of having a tiny balun ?
A 5 GHz collinear array will surely help users trying to avoid overcrowded 2.4 GHz band with dual band stock antennas with mediocre performance on both bands.
Thanks for clarifying.
Is the part number of the dual-band Alfa card correct? On the Alfa website, the AWSUS06H is only for the 2.4 GHz band, is it not?
You can use a 90 degree SMA connector.
The usual design for a dual band router is the 2.4 GHz band uses the external antenna and the 5.8 GHz band uses the internal PCB antenna. 5.8 GHz routers for household use were not designed to function over a distance but rather to add bandwidth. A dual band router is a hybrid legacy router as it should do 802.11 A,B,G,N. Unfortunately this is not the case one cheaper routers.
Now in a true dual band router the load of traffic can be shared between two antennas. If you change the factory firmware you can assign which antenna does what. If you want greater distance then you go lower in frequency but sacrifice bandwidth. Example is 900 MHz Ethernet bridges can have a range of a mile or more depending on antenna and location. 2.4 GHz can travel up to a couple of city blocks and 5.8 GHz can travel across your home. Also keep in mind that you are dealing with microwaves and depending on your antenna and it's gain the ERP of microwaves can become a potential issue. 1/2 a watt at 5.8 GHz is enough to burn you.
Hmm, I must be missing something here. I calculate the half length antenna for 5GHz should be 29.98mm and the quarter length at 2.4GHz should be 31.23mm a difference of 1.25mm; I'm using lambda=c/f with c being the speed of light, f frequency and lambda wavelength. Is the above equation overly simplistic for antenna length calculation?
@David Griffin - Agreed,... @ timeline 5:37 - I get the same calculation for 2.4GHz as shown in the video,... and 5Ghz LAMBDA as a straight 60mm. Why this difference in the calculation ??? Is there a resonance 'material factor' for copper (generally considered) x0.95 ??? but why would this apply to the 5GHz and not the 2.4GHz calculation which appears correct. ???
yes i will be making one but they are very small
thanks
Hi andrew. Thanks for the vids. I am going to try and make some ants for my RC stuff. i have 2.4Ghz for controlling my rc heli and 5.8Ghz for the video down link. I hope that a new ant on the 5.8 would be better tuned than the stock, as you have said it may just be ba standard 2.4 rubber duck.
What is the software that you are using to show the results of your ant. At the moment i have no way to measure my results.
Can you recommend a better type of 5.8Ghz ant to use the the heli which will be doing the video down link, i think that a normal rubber duck facing downward may get in the way as its stiff. Can i may some kind of 1/2 wave dipole?
Thanks for your reply in advance
Wonder if it can be diplexed, for cards that output both frequencies on one port.
That's a good one!
Hi Andrew. Your calculations seem to be a bit off.
Please let us know how you calculate the wavelength, because I got different readings when divide the speed of light (299792458) by frequency.
***** Sorry guys but you need to look up short bottom fed dipole Wikipedia has a section on this. Wave length is not set in stone or there would be no need for antenna theory.Lots of things influence design and materials used etc
***** That's it was going to post the same link when I got home so glad you found it.
@@andrewmcneil Reverse engineering the calculations for the 'materials factor' (reactance offset) K = 0.862 for v/c !!! that's quite a difference from the standard 0.98 - 0.94 values indicated. Very interesting,... is there a LOOK-UP TABLE for the 'v' value of electric wave speed in a specific conductor diameter ( or circumference >> thinking skin effect )???
.
Reverse calculating from K=v/c then,... 0.862 x 3x10^8 = v (MHz) - - then v = 258.6MHz for the velocity in the conductor versus AIR.
decoupling tube is not necessary, can you explain to me why? thanks
Please send me the link off online calculator for this antenna and thank you for this video
thanks prof
hi, I wonder if u can modify the alfa connector to connect tothe rounter by replace usb to rf-sma and get power inside the rounter power
Hi andrew thank you for your good work . I am ask for help i want to made a 15 dbi dual band and dual polarization omni antenna can you help ?
for me a 5GHz half wave is 2.85 cm with k=0.95. Not 2.586 like in the video
Have you tried cloverleaf and skew planar 5.8ghz antennas?
what do you think of this wide band antenna www.mdltechnologies.co.uk/products/3180b-broadband-mini-bicon/ 30mhz to 3 ghz claimed?
i don;t sleep ;-)
u got a lot of time on your hands bro
thanks
Please send me the link off online calculator for this antenna and thank you for this video
thanks
Please send me the link for online calculator off this antenna and thank you for the video sir