However these are not antennas but rather strange-looking ice formations called ice spikes.
I’ve also seen these spikes pictured on ice in a backyard bird bath and on ice cubes in a tray.
Ice spikes can form when water freezes inside an enclosure.
The water first starts to freeze around the edges and spreads inward until just a small hole or opening is left on the surface.
Since ice expands when it freezes the remaining water is forced up through the opening eventually forming a tube or ice straw.
As the water is forced upward it freezes around the rim of the tube and this adds to it’s length making the spike grow.
The tube will continue to grow until either all the water freezes or until the tube freezes shut forming a solid spike of ice.
It’s possible that a light wind may have caused the spikes to grow at an angle making them look like radio antennas. How strange!