Computing > Networking & Wireless

USB WiFi Adapter Antenna

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cdev:
If it has dual cables thats likely for diversity. Could you scan or make a better photo of the PCB antenna?


You can use a single rectangular 2400 Mhz panel antenna into a diversity antenna with gain by feeding the panel at two different places to utilize different modes on both receive and transmit. That is a very good antenna for a wireless AP with an angle of radiation of around 60 degrees. Well suited for a backyard or neighborhood. It needs a reflector behind it and needs to be rigid and held flat over its reflector in order to deliver consistant performance. If you fed the square at two corners separated by 90 degrees you will end up with a dual polarization antenna with  pattern that is consistent in both polarization plnes, basically, so its super useful that way.
you could use a coaxial stub to give you a circular polarization low gain directional antenna for its single frequency.

With the collinear, You know what I meant. Here is what I found with my martybugs style 3 element "collinear" made almost exactly like the one in the article. It does resonate at slightly above 2400 Mhz, good.

When used as a household wifi antenna it works well, as expected with a pattern thats not super directional but likely does have a bit of gain over the dipoles that came with the wireless AP. Works well on receive, picking up maybe 15 other APs.

SWR around 1.2.

Have no way to test the gain accurately.

For me this was a success. If I ever have a need for a 2400 Mhz omni again It will be used.

Currently don't really need it, my current AP has built in antenna. It has the pads for two u.fl connectors, that remove he internal antennas when n antenna is plugged in but it might be ugly. So I am just leaving it the way it is for now. Its a strong APas far as power goes, even deflecting my passive FS meter made with a 1n34 type diode and capacitor.


I will probably use this design again/ adapted for size, for other frequencies. (ADSB?, it seems ideal for that.)


If you want the 2400 panel dimensions I could measure it or scan it for you. That is even easier to make than the colinear. Just need some copper sheeting and tin snips.

E Kafeman:
>It does resonate at slightly above 2400 Mhz, good.
I very much dislike when someone intentional is spreading false information in opposite to my already above written information.Both of us can not be right, one of us is lying.
I have written that it is a useless antenna design and you is writing opposite.

I state that there is no resonance related to wifi for this design.
Even with very simple antenna knowledge is it easy to understand that it is a rubbish random wire, not related to antenna design.
>Have no way to test the gain accurately. No excuse at all, especially as if you says this is an good antenna design, as I then must be wrong.
Basic checking if it is an antenna at all is very easy done if you have bent actual wire by yourself. You must have done some kind of check? VSWR value, from where have you got that if you not have done any checking?


One real simple method to check if antenna is working as intended:

1. Connect the antenna to your wifi adapter or router and use free software to read RSSI if such software not is already included.
2. Place hand at antenna above 1:st coil and there will be almost no reduction in performance, less then 2 dB, as these parts not add anything to antenna performance more then any random wire would do.
3. It proves that these sections are useless and just to minor degree affect antenna efficiency and gain.
4. Remaining antenna bottom section. is a 61 mm straight wire. No clever calculations needed gives that what now remains from above simple test is mainly an endfeed 0.5 lambda antenna at 2.4 GHz connected to a 50 Ohm port.

Just by knowing how long a resonant length is can it be proved that this design NOT is resonating at 2.4 GHz. Rather simple math skills needed.

So what is performance for this antenna?
It have obviously negative gain due to its high reflection losses.
VSWR is not even close to what normally is acceptable.


>For me this was a success.
Lets measure your design. We already expect it to behave similar to an endfeed 0.5 lambda antenna but an simple check to verify VSWR:

As can be seen, even if scaling dimensions, there is no better tuned frequency, nothing to tune for improved result.It is nothing else then a random bent wire, resulting in an unusual poor antenna.


This Smith chart for the actual antenna confirms that this design have an impedance similar to a 0.5 lambda monopole.
Just by looking at actual design could that be predicted.
Endfeeding a 0.5 lambda wire from an 50 Ohm port will never be impedance matched.It is not even close to a resonance at 50 Ohm, center point at above Smith chart.So mr cdev, have you measured a VSWR below 1.2:1 for a design for which it is impossible?  Did you misread? It was maybe 12:1  or 120:1 as that is closer to a possible truth?One of us must be wrong. You or me?

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