External antenna suggestions for Monteino R96 433 MHz

[r.rabin]

Hello,

1) Is the u.FL connector compatible with the Moteino (R6) board? If so, are there any videos or tutorials on how to solder the u.Fl onto the printed circuit board?

2) Is a large increase in range expected in using a 5dBi mag mount antenna (such as in the link below) vs. the wire antenna included with the Moteino?

https://www.amazon.com/Antenna-433Mhz-Connector-Straight-Magnetic/dp/B01MV2LXMM/ref=sr_1_1_sspa?s=electronics&ie=UTF8&qid=1526614619&sr=1-1-spons&keywords=433mhz+antenna&psc=1

Thank you!

[LukaQ]

2.
That is a good question, to which I say, it depends. how so?
well depends on this new antenna + coax + connector, how well are they matched to the output of RFM. Is this new antenna really 5dBi as it claims? Is it then connected with coax that will not introduce large amount of reflections from antenna back to RFM?
If you know (or test), that you have 5dBi more gain, then yes you will see increase in range.
Maybe first and simple question is, how low is your RRSI, that you feel, that you need higher gain antenna?

[john4444]

Hi R.Rabin,

) Is a large increase in range expected in using a 5dBi mag mount antenna (such as in the link below) vs. the wire antenna included with the Moteino

It is not likely. First, even if the antenna itself does actually have 5dB of gain, you will probably lose more than 5dB in the cable and connector.
So... my experience has been that in order to get performance better than the wire included with the Moteino takes considerable effort.
Think along the lines of very low loss cable, direct connections and multi-element high-gain antennas.
It is very easy to lose every gain provided by an advanced antenna in the connectors or the cable between the radio to the antenna.
That little wire is pretty hard to beat.
Good Luck

[r.rabin]

Thanks for the advice! I suspected that the wire antenna might be hard to beat, so it is good to get your thoughts.
As yet, I haven't done extensive testing. I need to get my base station outside and away from buildings to etst the maximum range between Moteinos.

-Bob KA5MIZ

[ChemE]

The PCB dipole antennas are known to perform better than the soldered wire monopole provided they are connected with a feedline of appropriate length.  The eBay antennas mostly seem to test worse than they claim and notably worse than the simple wire monopole.

[perky]

The PCB dipole antennas are known to perform better than the soldered wire monopole provided they are connected with a feedline of appropriate length.  The eBay antennas mostly seem to test worse than they claim and notably worse than the simple wire monopole.

This has always confused me, the only reason why feed length might be important would be down to mis-match of the impedance of the dipole feed point to the coax. If that were true, would putting an impedance matching balun at the feedpoint add more insertion loss than the gain you'd get by proper matching?

Mark.

[Kilo95]

Anything you put in the feedline/antenna system will generally cause more loss. That said, appropriately matching the feedline/antenna to what the xcvr expects to see for impedance should cause an increase in effective radiated power (ERP). Most xcvrs cut back power if the SWR or impedance is out of acceptable range. so even with the increased loss from the balun, i would expect more ERP using the balun.

That said, I am using ChemE's PCB dipole with the premade SMA jumper on my PWS outside. (I don't recall the length of it but it is listed in ChemE's post on here about Alternative PCB antennas). It is roughly 175 feet from the PiGateway which is in my basement in the center of the house. It rarely ever misses a packet that I've seen. I am using the 915 MHz moteinos by the way

[Felix]

That said, I am using ChemE's PCB dipole with the premade SMA jumper on my PWS outside. (I don't recall the length of it but it is listed in ChemE's post on here about Alternative PCB antennas). It is roughly 175 feet from the PiGateway which is in my basement in the center of the house. It rarely ever misses a packet that I've seen. I am using the 915 MHz moteinos by the way

Kilo95, can you link the exact version (post) of the dipole version you used?
The one with wide radiators has been tested to be shifted to about 1Ghz+ center frequency, and ChemE posted a revised version based on these findings.

[Kilo95]

sure! Here is the one I used.  https://pcbs.io/share/4XRDg

It's not the newest one but the one referenced in Oct 2017 on the Alternative PCB Dipole post. (https://lowpowerlab.com/forum/rf-range-antennas-rfm69-library/alternative-pcb-dipole-designs-(433-868-and-915mhz)/)

Here is the info posted there on the feedline length:
Ideal Feedline Lengths Additional information from Captcha on this subject
To get the strongest signal with the lowest noise, the feedline length should be λ/2.  This length is technically from the ANT pin of the RFM69 to the point where the two resonators diverge away from each other on the PCB dipole.  Corrected for typical velocity factors, the ideal feedline lengths are as follows:

433MHz = 22.86cm implies a 21.26cm pigtail
868MHz = 11.40cm implies a 9.8cm pigtail
915MHz = 10.80cm implies a 9.2cm pigtail

Note the the connection between the end of the pigtail to the male RP-SMA jack is around 1.6cm in length so you need to subtract this distance to get your nominal pigtail length.