The BIG and SMALL ANTENNA topic part 2

Where can I find mounting brackets for my RAK antenna ? This is my antenna:

I found these brackets: https://www.123satelliet.nl/blueqon-WMM10-Muurbeugel-Zware-Uitvoering but these are oversized.

most brackets sold in dish shops are heavy duty
http://www.antennebeugel.nl/beugels.html

I look in auto accessory shops for exhaust pipe clamps. They have a range of clamp sizes to suit the wide range of pipes found on different make/model cars.

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quick%20antenna

Quick and dirty 868MHz antenna in 5 minutes

I have 2 of these absolute junk super cheap fake nagoya 771 antennas in my junk box :sunglasses:

x1660
x1661
x1662

you think they can be ‘tuned’ … cut , to 868 ?

  • update - experiment failed :rofl:

x1663

I could have told you that before you cut it. These antennas are designed to be tuned to 2 frequencies and both sections are dependant on each other.
For example: one antenna is tuned for 144 MHz and then electically sized as a 1/4 lambda antenna. at the same time it is tuned for 430 MHz and electically sized as 5/8 lambda antenna.
What happens is you cut it somewhere to change resonance? you will have to cut is twice to stay resonent in the way you want. It will not respnd as you hope. You know now :grimacing::grimacing::grimacing:

yes I did … the fr center indeed changed, but just a bit to 220 Mhz … lesson learned , 1.80 wasted :innocent:

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I found this one:

€ 6,99 | OSHINVOY Outdoor patch antena installatie L beugels Antenne fixatie holding pole U bouten beugel
https://s.click.aliexpress.com/e/s5YXAxlQ

May is this some thing for you, only use the brackets.

Hello @gaguilar,
i really appreciated your question concerning the size of the wires and copper part in the antenna. Did you manage to understand why they call this 868Mhz tuned while it seems to be a wrong size ?
thanks for your insights

I stumbled over this simple mount for RAK antennas. Not for outdoor! Would be great if this should be available in a material that is resistant for outdoor use.

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What do RF-engineers do when they are in self-chosen isolation: They measure antennas!
These antennas I purchased for experiments and specific projects

868 MHz dipole

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The antenna is good for 868 MHz with > 17 dB return loss.
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868 MHz logper

I purchased this antenna to connect to a node that has poor coverage at the edge of the TTN coverage of our town. 19 Dollar is a good price for a logper. The downside is that I have to reduce power from the node to meet regulator constraints.

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At 868 MHz a return loss is delivered of 20 dB (very good!) The two dips are caused by the different length of the elements of teh dipole.
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This antenna is painted for cloaking purposes.

434 MHz antenna

This antenna I purchased for an experiment (Not LoRaWAN).

image
Although this advert is no langer available, equivalent types can be found.

The antenna perfoms OK with > 11 dB Return loss.
image

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Does anyone has design for 868MHz PCB antenna or know where to buy some that can be useful? I’m looking something that I can use inside of enclosure, possible some tracker. Thanks :smiley:

Try a Google search on;

texas instruments 868mhz pcb antenna

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Hi @slaven96,

I use Molex 105262 and Taoglas PC81.07.0100A.db. Both are really good as products that can be purchased online.

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Hi all,
Have quick question regarding Antennas,
Currently I have two 868 and 923 band Kerlink Wirnet Outdoor Gateways. Also we have Antennas for 868 band but not for 923. I know that technically Antennas are different from each other but i would like to know how does it impact if one is used for different band gateway ?
Thanks in advance.

It would depend entirely on the antennas in question.

They might be fairly broadband so there is little difference in performance between using on 868Mhz or 923Mhz.

They might be fairly tightly resonant on the particular band so that there is a significant degradation when using an antenna on the wrong band.

To be sure of the impact you would need to check the antenna tuning, with a vector network analyser for instance.

Hi,
Thank you so much for very quick response.
Actually we wanted to do a test in field where the gateway is 500 meters away. Unfortunately we don’t have Antenna for 923 band in which we wanted to carry out the test. So just a thought what happens if I use 868 band antenna for 923!
Excuse me for questioning again, As I said above if i use other band antenna will the existing performance of the gateway reduces ? OR efficiency ?

Thank you.

First thing to worry about is legal implications. In most EU868 countries the frequencies used for 915 will not be freely available as they are used by mobile operators. Are you allowed to use 915 outside a rf shielded room?

If the antenna is tuned to 868 very well you performance will be greatly reduced, a significant amount of energy will be reflected back to the gateway which in extreme cases might even cause damage to the gateway.

Hi @kersing,
Thanks for the reply.
We have got legal permission for using 915/923 bands for R&D purposes So we are allowed to use them for limited period of time with in company premises.

As you said, we can’t use 868 band antenna for 915/923 gateway. I really appreciate your conclusion.

Excuse me for last query, we have field setup approximately 500 meters away from Kerlink Wirnet Gateway [ https://www.kerlink.com/product/wirnet-station/ ] in clear line of sight but with out Antenna. Question is, In this scenario Do we still need Antenna ? Will there be any packet loss ? Could you suggest me.
( Background : we have ordered Antennas but due to COVID it will take 30-40 days to deliver, so to avoid blocking us I’m stressing about antenna)
Thanks in advance.