=aircraft =radio =security
Various companies make anti-drone
"guns" (hereafter "ADGs"), which are self-contained jammers that are held
like a rifle. Here's an image
search;
you can see a variety of "barrel" styles.
They do actually work for
jamming small UAVs, so what's the problem? Well...
directional antennas should be
dishes
Those ADGs are generally using
Yagi antennas,
with a beamwidth
of maybe 30 degrees.
At the size of those ADGs relative to radio
wavelength, dish antennas give narrower beams. That's why highly-directional
antennas use dishes. You don't see satellite dishes using a long stick with
no dish, do you?
Dishes also have their weight closer to the user's
center of mass, making them easier to handle. Weight becomes harder to carry
the farther from the torso it is.
batteries are heavy
Those ADGs use batteries. Batteries are heavy, and they don't need to be
fixed to the antenna part. If the batteries are put in a backpack, then the
user doesn't have to carry as much weight with their arms. Separating the
batteries from a jammer also makes it easier to change batteries if they run
out.
military cosplay
Why do
ADGs look like rifles, if they don't need to? The answer is, "to look like
rifles". But making things that aren't rifles look like rifles has a number
of problems, such as:
- It can make nearby people unnecessarily
worried about getting shot.
- It can give users the wrong attitude.
AI is coming
Drone
jammers only work on drones that need radio control signals.
A guy I
know was designing a military UAV meant to be part of a strategy for
deterring war over Taiwan. A low-cost UAV designed to take off from normal
roads in Japan, carry a payload to China, autonomously find and attack a
target, and return. Part of the logic for that was that reusability is
somewhat more stabilizing than missiles that enable a massive first strike.
So I asked him: "Weren't you against that sort of thing?" And he
replied:
Yes, this is why I didn't release my image segmentation work, but there's no credit for being one step ahead of Joseph Redmon. Autonomous targeting is now too easy to not use.
Indeed, with the right software, many
cellphones can now do object recognition fairly well, despite being small
and (compared to military equipment) quite cheap. Yes, that software is not
yet reliable for camoflaged objects, but cheap UAVs don't need that.
So then I asked him, "Do you want to see this implemented, then? Do you
trust the US government to wisely use the ability to bomb things more
cheaply?" And he said:
I trust [my friends] will use its parts reasonably or, more likely, not at all. The engine & composite manufacturing techniques are the parts most likely to be useful. How about you? Or is this for a public post?
(Yeah.)
Countries are already using UAVs
that:
- are low-cost
- have long range
- attack using
autonomous targeting
We don't yet have a combination of all 3 of those properties, but it's coming.
a modest proposal
What
would a logical design for a manually-aimed drone jammer be? Well, let's
start by putting the battery in a backpack, connected to the jammer by a
cord.
As mentioned above, we want a dish antenna. When a drone is
visible to an observer on the ground, it tends to be at a high upwards
angle, and it's awkward for people to hold things upwards at a high angle.
So, it makes sense for the dish to normally be pointed mostly-upwards.
In that case, it makes a lot of sense to put it on top of the user's
head, mounted to a helmet. That way it'll be directly over their legs. It
should be pointed a bit forwards, maybe 20 degrees, but not so far forwards
that it blocks the user's forward vision. The sight would then use an angled
mirror. As a bonus, the dish would somewhat protect the user from the sun.
It might be good for the users to be easily visible to other people on
the ground, so they can be quickly found if somebody spots a far-off drone.
So, let's paint some bright yellow petals around the bottom of the dish rim.
And now our drone jammer design is complete.
With this design, even
if the anti-drone security people are quickly made ineffective by AI, at
least they'll be entertaining.