Reminder to RF specialists--Antenna RoadTest Needs You

With seventeen years of RF experience, much of it garnered during the tube era, I have little access to resources to do testing.

I wish I had access to the RF test equipment because I would love to try and provide radiation pattern for the different antennas.

I wish you the best of luck.

Sean

Sean,

Thanks for the comment. I was aware that this may be the issue for some roadtesters when I agreed to running the roadtest. But I think it's a roadtest I wanted to run anyway. It's a necessary part of a wireless solution and I felt our community, and especially the makers should know more about antennas.

Randall

Without a network or spectrum analyser there isn't much testing one could do. Eventually those that have roadtested such test equipment will join this roadtest...

Hi!

There was some thread where various ideas were suggested if there was absolutely no RF equipment. Examples were transceiver boards, for more subjective/empirical types of tests, e.g. to confirm range, sensitivity to nearby hand detuning, etc. or even using receivers or home-made power meters.

For home use, where there is a small budget, then for a basic comparison of antenna bandwidth or tuning, a software-defined radio could be another option to do it cheaply.

Regarding which SDR could be feasible, I only have LimeSDR so cannot compare with the other possibilities, but I feel the LimeSDR hardware is great (although a few quirky design choices here and there), but the software still needs work, although there is plenty of it out there, the documentation is weak. So far using the available software I've got it to arbitrarily generate a signal at a desired frequency, and also some extremely basic FM tone, and for receiving signals, I used some software that is spectrum-analyzer-like.

From using the SDR, I'd say it's a _very_ basic alternative for an SA, but is just about usable. All design engineers in firms should have access to a spectrum analyzer I hope, but there could be many small firms that may not realize the need for it : (

Even the cheapest real SA (a modern low-cost one, not the very ancient decades-old ebay boatanchors which are totally worthless - I'm trying to get rid of one) would be better for general use compared to the SDR, but if there is the absolute minimal budget for RF hardware, then the SDR could be an option maybe. Today the LimeSDR-Mini would be a better choice than the original LimeSDR I reckon, and is $159.

Screenshot is from an 868MHz transmitter, spectrum being picked up by LimeSDR.

I spent a number of years in, around, fixing, and site testing antennas and RF systems.

While the theory transposes to the higher frequencies, the equipment to test these is a little harder.

As others have commented, the interfacing between connectors may well have the greater influence, than the actual antenna.

I note that the chip style are going to be on a breakout board, which hopefully has the same connector.

If this is the situation, then swapping and repeating the same experiment, should should advantages.

Testers should be able to test the radiation pattern of the antenna, but care is needed so that the fixture holding it doesn't influence the readings.

In theory all these antenna are omni-directional, and presumably they all have the same gain, so while this provides a comparison, I'm thinking that the manufacturer already has these published.

Whatever the testers do or use, they will need access to RSSI or the ability to antenuate the signal to a known point, and the ability to communicate with the device under test.

In terms of importance, yes the antenna is one of the critical elements, however the design, testing and other requirements probably mean that most makers and users here will opt for COTS (Commercial Off The Shelf) designs, rather than scratch building a 2.4/5GHz device.

It's not hard at these frequencies to have the wrong pcb characteristic destroy all the careful work you've done laying ot put and adding the matching components between transmitter and antenna.

Good luck to the testers, but sorry this is one I don't have the equipment for.

Mark