Hey guys, so I’ve been building some DIY dual-band (2.4/5GHz) antennas for my home lab setup. Tested them on a VNA, SWR looks solid, and the resonance is right where it needs to be. But now I’m trying to test them in the real world around my house and backyard, and I’m losing my mind.
I’m walking around with my phone checking RSSI, and on one antenna I get like “80%”, and on the other, it’s “65%”. Or in another app, it shows RSSI values like 45 and 55. But if I take one step to the left, the numbers just jump all over the place. How do these RSSI “points” even translate to actual dBm? Is there a reliable way to tell which antenna has better gain?
RSSI is basically just “vendor points”. Broadcom, Atheros, Realtek — they all have their own proprietary formula for calculating it. For one chip, 60 is max, for another, it’s 100. It’s pretty useless for actual benchmarking. You need to look at actual dBm values. But even then, keep in mind that dBm is logarithmic. -60 dBm is way stronger than -70 dBm (it’s not just a “10 point difference,” it’s a huge drop in power). Also, if you’re testing dual-band, an antenna can be awesome at 2.4GHz and completely suck at 5GHz. One-spot testing won’t cut it.
@RSSI_Master Thanks for the breakdown on the log scale, that makes sense. I managed to switch my Android app to show raw dBm now. As for my testing method: I set up a tripod like 60 feet away from the router, behind a drywall and a brick wall, and clamped my phone to it. I swap the antenna on the router, wait a couple of minutes, and log the average. With antenna A I get around -65 dBm, and with antenna B it’s -72 dBm. So antenna A gives me a 7 dB advantage, right? Is that a solid gain for a DIY build or just margin of error? Because if I literally just stand between the router and the tripod, the signal tanks completely. How do I get a clean test?
A 7 dB difference is actually huge. That means antenna A is delivering roughly 5 times the signal power of antenna B. So yeah, your DIY build is definitely doing something right.
If you want a more realistic comparison, test both antennas across multiple points, not just one spot. You can use something like NetSpot for this. Run a survey with antenna A, save the heatmap, then switch to antenna B and repeat the same route with the same router power, same channel, same band, and same client device position. Compare the Signal Level maps in dBm separately for 2.4 GHz and 5 GHz. That won’t give you lab-grade antenna gain, but it will show which antenna gives better real-world coverage in your house and backyard. Basically, don’t try to turn one random RSSI number into a verdict. Compare the full coverage pattern. No guesswork.
@Major_Peter Oh, that actually makes way more sense. I was trying to turn one number into a verdict, but comparing two heatmaps sounds much more useful. I’ll try running the same survey route with both antennas and check 2.4 GHz and 5 GHz separately. Thanks, this is exactly the direction I needed.