The BIG and SMALL ANTENNA topic part 1


#123

I was thinking about doing relative gain measurements, a bit like @lex_ph2lb did here (comparing antenna’s).

At my work we have a lot of greenfield terrain that would be suited, and maybe I can fix access to the roof of one of our 12-story high towers. But that’s in Ghent :wink: .


(Remko) #125

So we have two requirements:

  1. measure impedance and so get an indication of frequency (return loss (VSWR))
  2. Antenna efficiency measurements

both have different requirements for the environment :slight_smile:


#126
  1. cable loss measurement (bring your cable too :wink: )

(Gry Kyo) #127

So how did this work out?
I have one the same as this on the way and assembled the hardware to put it on a 5m pole over my house today. I won’t go back on the roof until I have this delivered but interested to know what you discovered testing. Go on, tell us all?


#128

very happy with it and gonna use it as my ‘main’ antenna :wink:


(Reinier van der Lee) #129

Hi Laurens, have you considered using ARRL course materials? I am sure they have what you’re looking for, and probably happy to support. ARRL, the national association for Amateur Radio, hq@arrl.org


(Gry Kyo) #130

Tracking says that my antenna is due for delivery today but I am thinking I should admire it’s elegance indoors for a day or two. If I climb on the roof to install it today this could be my last post to the thread; 12m high sea swell and 121kmh winds!

34

That said, I am looking forward to the next round of testing and that reminds me; have we a tutorial or example of how I might downlink to an end device and use a character to call pre defined routines stored within (LMIC & Ardyino IDE)?

Thx, G


#131

I tested the other way…
send the same packets to the same application with the same node but with the different antenna’s.
then I compare the received gw signals on the console (application data)


#132

this one just arrived :sunglasses:


my neighbour asked if I was making bombs … :rofl:

the 2 dbi puck antenna seems to work fine (just reached 13 km)


(Gry Kyo) #133

I have one of these which I have yet to test. I am not sure how much signal is attenuated when the node is at ground level, consider an arable agri application for example. I can imagine this antenna placed on a post to gain some elevation if only a couple of metres. My lack of RF or Antenna knowledge may be very obvious but would this unit benefit from some sort of ground plane, if it was mounted on a metal sheet/plate or even a mesh? If so, what would it ideally look like in size and shape?


(Gry Kyo) #134

And I may get to test this later today. I received an antenna the same as the one @BoRRoZ uses here

today and found that the RSSI from a node sitting in my car outside (not on TTN network) changed from


to

just by changing the gateway antenna which is still in my attic space. Maybe later in the week I will weather proof my gateway as it is running on a single ethernet cable with PoE as is, just one step to get it all installed on the roof.

I will try the antenna @BoRRoZ is using above:

later if I can graft a connector onto a node. I am curious to see if I get the sort of range which would be practically useful for some of the applications I am developing. Any reason why I shouldn’t solder the centre pin and one leg of a pcb type SMA connector to the corner of a RFM95 module, ANT and GND are side by side?


#135

no problemo I think :wink:


(Gry Kyo) #136

Well that didn’t take long…

The local pigeons have decided they like their new 3dBi perch!


#137

LOL :sunglasses:


#138

11 dbi and 13 dbi:roll_eyes:


#139

nice story from Garry https://www.thethingsnetwork.org/community/dublin/post/a-popular-gateway-upgrade


(Gry Kyo) #140

Thanks BoRRoZ! Finally got the gateway and outdoor antenna permanently installed so the antenna experts here may advise about how effective the shield on the rear of my TV’s array antenna will be for blocking LoRa to my new 3dBi antenna? Should I lower the array below my LoRa antenna for better omni-directional?

Does this antenna/gateway combo work? Well yes, I have received packets from just over 15km but from high ground, it is not totally flat around my house. I used my home made 1/4 wave ground plane from the @lex_ph2lb design on a Pro-Mini node with RFM95W radio but didn’t hang around long enough to try other antennas on my node. I have however seen over 5km with one of those tiny 50mm long sma antennas so next testing is to see how close to the ground I can reliably place my node without attenuating too much RF energy.

Garry


#142

I think its always better when an omnidirectional antenna, like the one you have installed, is ‘free’ all around so no reflection/blocking/attenuation ect. … but to climb on the roof immediate… take your time to expiriment a bit and watch your console / application


(Reinier van der Lee) #143

We’ve been using these $30 antennas and they work fine. We get 6 miles distance. Here is a picture of a gateway and antenna installed on the roof of a local winery in Temecula, California.


(Gry Kyo) #144

I am curious to know if you have to be careful with node placement, specifically height over ground? One application we’re lookig at has the nodes on or effectively just below the ground! Not much data yet.
Thx, G