canantena
Do anybody know how to measure gain of an antenna? I am using Pringles can antenna, but not sure exactly what gain I am getting out of it...Plz help if you can
Thanks
Mitesh
If you have access to another antenna and some method of measuring received signal strength you can compare the received signal level with both antennas and at least tell which one has the higher gain. If you have an attenuator that works at the frequency you are using you can put it in the line and cut down the stronger signal to make the received signal levels equal and the attenuator setting is the gain advantage of the antenna that needed the attenuation.
The practical proof of the pudding is if it works better than any alternative you have. That is, better noise quieting on a distant transmission.
hi
Thanks. Actually, I have a spectrum analyzer and an additional Yagi antenna (model # HG2412Y). I am using a loptop with pringles can antenna as my transmitter. Since I am working in lab, I have other signals (from several access points) that I am receiving. So I think, If I check received signal in Spectrum analyzer, it will not give me correct Signal power.
Do you think setup that you just told me will work?
If you have a commercial antenna that you can trust you can connect it and the pringle antenna to the spectrum analyzer alternately and compare the readings. You can use a signal generator and any antenna for the transmitter source. To eliminate reflections, do the test outdoors and have the antennas many wavelengths above ground and many wavelengths apart to make sure you are in the far field.
Is there any way I can still do testing in the lab...Is there any way we can eliminate the reflection?
Indoor measurements are very difficult which is why companies make a living selling chambers with absorbing material on the walls.
One test you can do is the SWR on your antenna. This will be a good indicator of its working properly.
If you do not mind errors of up to 6 dB in gain measurement, you can try some indoor measurements.
Hi!
Directivity of this type of antenna is around 8dBi. So the gain is slightly lower, you can count with 7dBi.
Regards,
eirp
PS: I'm using this antenna with cone for internet connection, obtaining directivity around 15dBi.
For aperature type antenna directivity is very well theory defined (and practical improved)and because they are very common used like ethalons.
Pringles can antenna is very popular :D but guys don't know calculations are wrong, especially monopol feed lenght.
As eirp said this antenna has directivity about 8-9dB but not gain because bad return loss(high SWR).
Post your pringle dimensions and I'll calculate other parametars for you.
Hi, goxy and all!
If you design can well, it has nice SWR!
The mine shows S11 ~ -15dB at the middle of band.
But generally, this antenna is shit for WiFi in cities because it's wide mainlobe (60-70degs), causes interference with other clients..
At least, simply add a proper cone to create horn!
rgz
eirp
Hey Goxy,
Diameter of my Pringles can antenna is 74mm, & length is about 230mm
Also, I will like to know how can u calculate the range of this antenna? Please help me if you know. I am trying to set up a network using these kinds of antennas, so I want to find out range, directivity (beam width) and gain
Thanks
Mitesh
for the calculation we need also details concerning the feeder - distance from the end of can and wire diameter.
Range depends on other factors you not mentioned:
- type of your WiFi card (sensitivity levels)
- needed speed (1,2,11Mbps..)
- losses in your cables (lenghts, types)
- environment between antennas
very roughly, the range will not exceed 300-500m in free space.
Best
eirp
- type of your WiFi card (sensitivity levels) - Orinoco Card
- needed speed (1,2,11Mbps..) - 11Mbps
- losses in your cables (lenghts, types) - For now using two connectors and small wire...Later on we will use LMR4000 with about 50 feet long
- environment between antennas - I am planning to set them up on two sides on street...but mostly there will not be any obstacles in between
Thanks,
Mitesh
Hi eirp!
Guys from WiFi comunity networks have bad calculator, and because they make antennas with bad SWR.
Miteshparikh,post and the feeder distance from the end of can, wire diameter and wire lenght.
BTW. Diameter should be larger than 75mm, try to find about 100mm, lenght is 120mm and more for 2.4GHz band.