ADS-B DIY Antenna

ADS-B DIY Antenna

How I made the first antenna to give me 200-mile ADS-B range

plus…ongoing testing of individual improvements (or adjustments, as I like to call the ones that go in the bin)
Antenna 2

This experimental learning started as a means to simply test that I’d got an ADS-B receiver working and was in an area where I had a chance of getting some data, before I splashed out on a decent antenna.

As it goes, I was hooked on improving my attempts almost immediately and realised that there’d be more fun to be had by using a DIY antenna than by buying one. So, I started reading and attempting to integrate various design options. Very quickly, I realised that some worked, some didn’t and some did positive things but not necessarily producing results that gave me what I was looking for.

Going forward, therefore, my plan is to run two receivers in the same approximate location with two antennas. I’ll make adjustments to one, compare performance for a week then either upgrade the other to match, or reverse the adjustment to match (depending on whether it was an improvement or not), before continuing with the next adjustment.

There are a few different sorts of antenna that work (apparently) – dipole, monopole, spider, and coaxial collinear. I’ve only attempted anything with the collinear. Although these articles show some people having success with others:

At present I’m at the point with a single design that gives me a set of statistics (from various sources, described below) that I’ll use as my “measurements”. Those statistics, and the antenna design they relate to, are here. How I got there is as follows…

Steps

  • Buy parts
  • Cut elements to length
  • Prepare joints
  • Tin joints with solder
  • Assemble antenna
  • Mount antenna

Jump down to the instructions to see what I did in each step, or read a bit more about my setup.

Introduction

https://discussions.flightaware.com/t/antenna-ground-plane/54800/11

https://discussions.flightaware.com/t/three-easy-diy-antennas-for-beginners/16348

https://forum.flightradar24.com/forum/radar-forums/technical-matters-hardware/6421-making-an-inexpensive-1090mhz-ads-b-collinear-antenna

My initial reading was this article

http://www.repeater-builder.com/antenna/wa6svt.html

And my first attempts were a 2.5-element version with no chokes, a makeshift feedline (two flexible multi-strand wires with crocodile clips) and no whip (I was still trying to understand what I’d read). It received, which was the initial aim, and I got a handful of aircraft on a map!

I then added some elements (but removed the half-element at the top), shorted the top with a short croc-clip wire and put some chokes on a longer feedline with an SMA connector that would connect directly to my USB receiver.

Eventually, I added a whip and got a much-improved but clearly-beatable 63-nautical-mile range from an indoor location on the ground floor of my house.

The next improvement was to move upstairs and I relocated the same antenna in the window of a back bedroom getting a massive improvement of double the range.

Finally, I added two more elements, shortened the feedline and added a thin decoupling sleeve. The pic below is that version in the back bedroom window. However, moving the entire installation to the loft (another 3 metres higher but otherwise in the same location – well, about 3m back into the highest part of the loft) gave me 267nm, about 50 aircraft simultaneously and a maximum of 550 messages per second.

Antenna 2

Instructions

So…the steps in more detail…

1. Buy parts
  • Coaxial cable
    • I used a 5m length of RG58/u cable with SMA connectors already fitted (like this, assuming this search still works at the time of reading)
  • Toroidal ferrite chokes (3 x FT50-43 like these)
  • You’ll also need a soldering iron, some solder, a way to mount the antenna (wood, 3d-printed “hanger”, plastic tube, etc), a craft knife and some wire cutters
2. Cut elements to length

Include the cutting template

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