Rfm69 and that pesky antenna
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Been using the nrf24 radio,s for some time but found the range in my house a little lacking so decided to switch to rfm69 radio,s instead.
So having got my head around the 5v intolerance etc,Only to have a problem with the enclosures now.
I have been using this enclosure with the nrf24 set-up:-
But i can not squeeze the 82mm antenna in here ?.
Suppose it will just have to stick through the slots:angry:
Is everyone using the rfm69 working with the straight antenna?
Also at the moment i have the antenna sticking straight up without the lid on.
Will it be ok to bend the aerial over 90deg so it comes out of the slots when the lid is on.?
It will still be mounted vertical when it is on the wall though. -
all manipulation/torsion you will apply to your antenna, or if antenna is near electronics etc.. will degrade its sensitivity, range.. of course!
but you can do this, no problem, it's all about compromise.
you can coil it if you want, like this
https://github.com/OpenHR20/OpenHR20/wiki/2.1)--433-MHz-and-868-MHz--Antenna-Design-Examples
sure the best is straight antenna, perpendicular to the board! and for monopole antenna, a good sized ground plane.
but with coil you may get a decent range.
it's RF story ;) -
I have tried this antenna with the RFM69:
YAGEO ANT1204F005R0915A
http://www.newark.com/yageo/ant1204f005r0915a/antenna-chip-915mhz-50-ohm-1204/dp/38X6113?ost=ANT1204F005R0915A&selectedCategoryId=&categoryNameResp=All%2BCategories&searchView=table&iscrfnonsku=falseVery compact. I use 915 MHz, but there are variants for 433 and 870 MHz. I have only tried 3 of them. 2 worked well and have enough range to get from the far corner of my basement to my gateway on the second floor. My NRF24 radios cannot do this reliably.
One did not seem to work at all, so I replaced it with a wound wire instead. My board is not designed for them and I am just soldering to a thru-hole round pad that is on a trace to the RFM96 antenna. That might have been part of the problem with the third one.I plan to put a pad for these on my next circuit board design. If you don't have a separate trace for installing an antenna, I don't think you will be able to connect these to the radio unfortunately.
I wish I had a way to measure the range easily. I'm sure it is not as good as the wire, but it works for my purposes and is very low profile.
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I've used this planar antenna on some RFM69HW's: https://www.digikey.com/product-detail/en/linx-technologies-inc/ANT-916-USP/ANT-916-USP-ND/3830737
It works OK, though there is some impairment if compared to the more typical straight wire antenna. Most likely you have enough link budget it won't matter. If it does turn out to matter ,though, then use a dipole antenna on your RFM69 gateway and you'll more than compensate for the impairment (https://www.openhardware.io/view/277/ESP8266-RFM69HW-gateway-with-dipole-antenna).
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I have tried this antenna with the RFM69:
YAGEO ANT1204F005R0915A
http://www.newark.com/yageo/ant1204f005r0915a/antenna-chip-915mhz-50-ohm-1204/dp/38X6113?ost=ANT1204F005R0915A&selectedCategoryId=&categoryNameResp=All%2BCategories&searchView=table&iscrfnonsku=falseVery compact. I use 915 MHz, but there are variants for 433 and 870 MHz. I have only tried 3 of them. 2 worked well and have enough range to get from the far corner of my basement to my gateway on the second floor. My NRF24 radios cannot do this reliably.
One did not seem to work at all, so I replaced it with a wound wire instead. My board is not designed for them and I am just soldering to a thru-hole round pad that is on a trace to the RFM96 antenna. That might have been part of the problem with the third one.I plan to put a pad for these on my next circuit board design. If you don't have a separate trace for installing an antenna, I don't think you will be able to connect these to the radio unfortunately.
I wish I had a way to measure the range easily. I'm sure it is not as good as the wire, but it works for my purposes and is very low profile.
@nagelc said:
I have tried this antenna with the RFM69:
YAGEO ANT1204F005R0915A
http://www.newark.com/yageo/ant1204f005r0915a/antenna-chip-915mhz-50-ohm-1204/dp/38X6113?ost=ANT1204F005R0915A&selectedCategoryId=&categoryNameResp=All%2BCategories&searchView=table&iscrfnonsku=falseThat looks very promising. But I have no idea how to design or tune the matching circuit called for in the data sheet. Any thoughts?
I've used these type of small helical antennas with good results.
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@nagelc said:
I have tried this antenna with the RFM69:
YAGEO ANT1204F005R0915A
http://www.newark.com/yageo/ant1204f005r0915a/antenna-chip-915mhz-50-ohm-1204/dp/38X6113?ost=ANT1204F005R0915A&selectedCategoryId=&categoryNameResp=All%2BCategories&searchView=table&iscrfnonsku=falseThat looks very promising. But I have no idea how to design or tune the matching circuit called for in the data sheet. Any thoughts?
I've used these type of small helical antennas with good results.
the other antenna to look at is what was done on some of the Motinio from LowPowerLabs with a flat PCB based antenna.
https://lowpowerlab.com/shop/product/145
I don't know if there are any opensource designs that people could bring in to use on their own prodcuts
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Thank you everyone for your input on this.
Eventually i just used a piece of wire 82mm long and bent it over and stuck it out of one of the slots in the housing.
Crude i know but the initial results are promising.
The Gateway is in one corner of the house upstairs and i placed the sensor in the opposite diagonal corner downstairs in the house through a guess of 4 brick walls and the sensor is reporting an Rssi of -65db ti -70db.
Shame Rssi can not be presented in Domoticz properly yet (Having to use a dummy sound sensor to visualise it) as mysensors has no way of handling it yet!.
I will be conducting more range tests but the change from NRF24 was well worth it (No more deadspots in the house).
