I need an antenna placed just above a metal tube with the diameter about 20cm and at a height of about 1 meter. The metal tube would get a PE piece (cap) above it to allow for radio transmission. The antenna must be inside the PE piece and rather central above the metal tube.
It needs a rather far reach inside woods or fields (easier).
Are there special considerations or is it sufficient that the bottom of the antenna starts just above the metal tube?
Which is the minimum needed height for the PE piece (also about 20cm diameter)?
Return loss
The return loss measurement shows that the antenna was designed with 929 MHz in mind not 868 MHz.
At 868 MHz the return loss is 8.6 dB which is not bad but also not good depending on the quality standard your use. (Not mine at least).
Antenna gain
For the gain measurement, I compared n RSSI reports from multiple gateways using a reference antenna (0 dBd dipole) and the DUT (The Delock in this case).
Reference antenna setup.
Delock antenna (after the measurement I was there for the picture)
The gain I observed was about 6 dBi and NOT the promised 10 dBi.
Conclusion
Antennas with this gain will definitely require a reduction of transmit power of the gateway connected to it. Else the legalisation rules for frequency use will be violated. As a result of the power reduction, link asymmetry will exist and will cause OTAA to fail at the cell edge of the gateway.
The antenna is not designed for 868 MHz
The antenna does not deliver the specified 10 dBi.
An antenna which does not deliver what is promised, and will introduce the problems I pointed at earlier in this post is not worth the money in my opinion. I wouldn’t recommend it to anyone.
Back to roots - gain is not everything. But radiation-pattern and position of the antenna. A simple 0dBd dipole with free environment and free Fresnel-zone can be much better than a 10 dBi-gun on a low roof.
imho we should not try to break distance-records but to cover a radius of a few kilometers with good field strengh.
Greetings antenna folks. I want to run two mounting schemes for a LoRaWAN antenna past the community here. I have an application where I need to mount an antenna to a sheet metal box. Picture a mini fridge - sheet metal with antenna on the outside, transmitting electronics on the inside of the fridge connected via coax cable.
I haven’t got a great intuition for how this will perform. Metal this close to the antenna can’t be good.
Is one antenna mounting scheme better than the other? Are they both atrocious and I should figure something else out? I prefer the side mount for non-antenna related reasons.
Let’s assume this box is at street level in a residential/medium density urban environment, and near a window looking outside.
it looks like some info may be cut off(*) but here are some specs for the sake of argument
Frequency Band 902-928 MHz
VSWR <2.0:1
Impedance 50 Ω
Gain 2.5 dBi
Polarization Vertical
Radiation Pattern Omnidirectional
Wave Half-Wave
I would strongly recommend option 2. Using option 1 the metallic box is in the near field of the antenna. That means that the antenna is detuned and the radiation-pattern is strongly influenced.
The position of the antenna is more important than the gain.
I have been on 4 forums and discord and nobody can tell me if I need to ground the antenna. If so how?
I want to place it outside of my loft window, halfway up my tiled roof. It will be used for a helium miner. I will me making a small platform for it. I do have a large 13 storey tower block 150 meters from my house, so I am not the tallest thing around.
So - not being used on TTN and for the benefit of TTN community then?! But you want a response on the TTN Forum?.. What did you get from the Helium support Forum?
For what its worth grounded and floating (depending on whether any attached network is effectively grounded/isolated) both valid - though likely its more a decision driven by how you hand Lightning protection (if any). Typically for effective lightning protection the surge arrestor(s) has a sturdy (defined by regs in most parts of the world) strap/cable to earth. The antenna behaviour will largely be independant of any associated ‘ground’ plane and in part influenced by any balun arrangement for the cable and ant assembly. It will have been characterised ‘free-standing’ at the end of a test cabe run… Ant types requiring real or virtual ground planes (often formed by angled or perpendicular side attachements) withh normally call this out or have tapped holes for bolting in the ground plane accessories, omni-directional monopoles like this typically used without additional ground planes - I use several of its smaller brothers… If mounted attop a metal cabinet or even a larger (metal) outdoor Gateway housing vs being cable fed at the top of a mast/pole the mounting then effectively adds a small amount of ground plane. support.
Thank you for your in depth reply.
Lots of people are buying these antenna to add to there helium miner. The discord forum has a lot of people commenting but were unsure, but you seemed to know a lot more on grounding.
When googling I found this.
“Fiberglass is an insulator, and not a conductor. As such, a plain fiberglass whip with nothing inside would not be an antenna. So, no, the element inside the fiberglass would not, or should not, be connected to ground. It should be connected to the center conductor of the feedline coax.”
Although this is on the internet it may not be true. Like to find many sources agreeing.
I will not be using a pole of any type, to gain more height. It will be 8 meters above ground, half way up a roof.
Ifthe answer is I need to run a cable down the side of the house and into the ground, then I will think again. Can I use the earth from the UK power supply and spur this?
No, absolutely not. The ground wire, if required and combined with a surge arrestor, is used to conduct the energy from lightning strikes to earth. Using a power supplies earth could result in personal injuries or even death and in all electrical equipment in the house and possibly your neighbors houses as well to be destroyed. And it would probably be highly illegal to do so. (Ask a friendly electrician for an opinion and please let us know the reply)
For lightning protection it needs to be a dedicated directly bonded line taking the energy directly down to local ground (earth) with appropriate installation… not an amateur task at all…as Jac says consult with an electrician on that.
Note the googled description is poor. The fibre glass is just an environmental protection… a weather proof housing if you will. The monopole element will be mounted coaxial inside it…though indeed connected to the centre conductor through (in the original case you called out) an N-Type connector, Or an SMA connector for the 2nd one.
That you even thought that might be a good idea is a strong suggestion that you ought to consult a professional electrician or antenna installer.
Using the mains Earth in this way might well be plain illegal, under the ‘Part P’ regulations what changes an individual can make to a electrical installation are very restricted these days.
Also remember that when using a gain antenna such as that you will need to work out how much you need to reduce your ‘Gateway’ transmit power so that it is still legal to use.
Hi,
Beautifully made antenna, but I wonder where the mount is? In general, the grip of another pipe should be under the counterweights. In other words, how is that antenna fixed?
I think this is the antenna on the RAK Wireless store… Its the only antenna with the range 860-903MHz on their store and the document with the polar plots for this antenna (follow the links) are the one’s I remember as RAK rotated the plots and added the antenna symbol based on the discussion in this forum at the time. At the time of the discussion in this forum it was called a 6dBi antenna but now is called 5.8dBi, but if you look in the documents it refers to the antenna as being 6dBi. I can’t be 100% certain its the same antenna but all the documents seem to suggest it is. Fiber Glass Antenna | LoRa High Gain Antenna | Long Range Frequency Antenna – RAKwireless Store
But you want a response on the TTN Forum?.. 
What did you get from the Helium support Forum?