RF antennas

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djoshi
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Posted by djoshi: Fri. Apr 10, 2020 - 11:10 PM
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Hi All

 

I hope you are well and safe.

 

I am working on small project over the weekend with 2.4Ghz ATmega128RFA1 device.

 

I have some old antenna that i found, which are the black hinged external antennas.

 

I can not remember is they are 866Mhz/900Mhz or 2.4Ghz. 

 

I need to do a small tests on my desk so not much distance.

 

Would using the wrong type cause any damage to the device or front end device?

 

I aim to order some some 2.4Ghz version next week.

 

Is there anyway of telling if the antennas i have are for 2.4Ghz?

 

Thanks

Thanks

Regards

DJ

Tags:

Learning and Information, General Electronics
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ka7ehk
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Posted by ka7ehk: Fri. Apr 10, 2020 - 11:43 PM
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Sometimes it is hard to tell without a network analyzer.

 

They tend to be similar length for a given frequency. Compare the length to what is on your WiFi access point.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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djoshi
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Posted by djoshi: Sat. Apr 11, 2020 - 12:00 AM (Reply to #2)
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Hi Jim

My wifi has it inbuilt.

As far as I remember I had 2.4ghz version as well a 868.

If they are 868 mhz and I use it on 2.4ghz device can cause any damage due to any power feedback?

Thanks

Regards

DJ

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ka7ehk
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Posted by ka7ehk: Sat. Apr 11, 2020 - 12:02 AM
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It will probably be OK, but I would not count on that, myself.

 

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

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awneil
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Posted by awneil: Sat. Apr 11, 2020 - 08:49 AM
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As Jim said, damage is unlikely at the sort of power levels you're talking about.

 

Performance won't be optimum - but should be OK for just messing about on your bench.

 

I am currently using a TI radio, for which the only available dev board is an 868 MHz version, but I'm using it at 433. It is OK for just messing about on the bench.

 

 

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sparrow2
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Posted by sparrow2: Sat. Apr 11, 2020 - 12:18 PM
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Just a funny comment from the side line.

15 years back I worked for a company that made AIS systems (i tuse 161.975Mhz and 162.025MHz). 

I was playing around with a 9833 DDS dev. board. And had a program that had a canned AIS packet to see if we could use it for modulation.

For fun I tried to modulate at ? can't remember the freq at the dev. but at a odd harmonic of the board freq+ or - my freq would be on a AIS channel.

10 meters from away from me came a big sound, "WHO are sending all the time". I had no ant. it just left the dev. board with nothing on the output (The open ended PCB trace was the ant.) 

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djoshi
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Posted by djoshi: Sat. Apr 11, 2020 - 04:36 PM (Reply to #5)
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Thanks

 

I will order some new antennas next week thanks.

 

I think module does output 18dbm .

Thanks

Regards

DJ

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