Has anyone experimented with an automated or concurrently adjustable antenna placement design? I’m trying to help a company that wants to use Kracken for locating rogue transmitters. They have a 900mhz system and a UHF System. I’m trying to make it easy for them to adjust spacing per frequency. They are a radio company but nor very radio savvy. Anybody have any ideas?
Thanks In Advance
there was design for linear setup with kerberos - A 3D Printed Automatically Adjusting Linear Antenna Array for KerberosSDR Radio Direction Finding - might be good starting point
Thanks! It seems like it being linear it would not config correctly with the Kracken.
This is a solvable problem—we even have some rough plans for a product. But it’s not a simple product, which means it will be expensive. We aren’t certain about the demand for a $2000 adjustable array.
I was thinking of swing out arms that would adjust element spacing while keeping the 72° angle (equal spacing) and using something akin to tape measures or the https://steppir.com/ type adjustable length antennas that would lengthen/shorten as the arms travelled further/closer to the center of the array. But the “ant 0” and the rest would change location from mid-line orientation…unless the hub rotated and the antennas slid on tracks…hmm, something like the iris shutter on an old camera. It is in my head, not on paper and not on the roof (yet) but I think it would be a very interesting approach to a problem we all are trying to solve.
For something simple to get you started, you could use a fixed array to cover both bands. For example, 13cm radius spacing gives you just under .5 multiplier for 980mhz (max) and .2 multiplier down towards 400mhz. Granted, you’re losing some resolution the lower you go, but it may be worth a try. Similarly for the antenna, if you can’t find a dual-band that covers both those bands, you may be able to just use a uhf duckie and still hear 900mhz.
I get acceptable results using multiband antennas on my daily driver. I use 2m-440 duckies at 28cm for vhf/uhf and an LTE 4G antenna for 700-1300 (rarely used, photo below).
You could also use a seperate array for each band and manually or electronically switch between them.
Just a few ideas- Happy hunting.
Imagine the 5 antennas in a circle on a disk.
From the center of the circle there are 5 straight tracks on the disk.
Each antenna sits in a track and can slide in and out to change the size of the antenna circle.
Now imagine a second disk, but this one has 5 spirals curving out from the center.
The spiral disk is overlayed the straight track disk.
As the spiral disk is rotated, it moves all the antennas through their straight tracks.
Because the straight tracks don’t turn, the zero heading does not change.
Add a stepper motor with gear and auto stops (like on a 3d printer) to calibrate and control the commanded radius based on the radio frequency.
Excellent idea! Now add to that a third element (pardon pun) that increases the length of the antenna (all 5) as they track away from center. I have contemplated some mechanism like a retractable car stereo antenna or that which is used in StepIR antennas. It would be so much easier if they needed to get shorter as they moved from center, but they need to get longer. So the flexible medium (track, tape, filament, cable, etc) that is pushing the collapsable (telescoping) antenna longer must be at the distal ends of each arm.
Great start HH80, let’s keep brainstorming!
I think you are just better off having a wide band/multi band antenna to cut down error
