Depends. If the antennas were resonant dipoles placed some fraction of a wavelength away from each other (1/4 wave away), you may get some cancellation of the signal.
Look up the “yagi uda” antenna, it’s the classic rooftop tv antenna. The elements are spaced by fractions of a wavelength to achieve directivity. One single element is driven, the others are just resonant lengths of wire.
People are answering what you asked but what you probably mean is in a 2d world where two antenna are perfectly in line with the transmitter will the first absorb some of the signal - yes it will, just like two wind turbines in a line it’s absorbing the energy from the medium and using it to do work.
It’s not always so simple, it might spit some of if out too if it doesn’t have anywhere else for it to go and it’ll do this in a certain pattern which can, depending on the distance and arrangement ,increase the signal received by the second one. This and similar principles are why you see so many odd shapes for antenna designs such as the many bars on a TV antenna which make it more directional.
You and the person on a chair on the beach next to you will both get sunburnt. In the same way, radio waves washing around your house or car interacts with everything, antenna or not.
Ham radio operator here: basically neither will happen because both don’t really mean anything.
This is an imperfect analogy, but I think it will set you thinking in the right direction: If someone is blinking a flashlight at you, and you’re sitting right next to another person, do both of you see the flashlight at 100% brightness, or do your eyes wrestle for the same light waves?
What does “pick up the signal at 100%” mean? Let’s say me and my buddy are talking on our car radios, no repeaters just point-to-point. If we start off in the same parking lot, we can easily hear each other. If we start driving in opposite directions, we’ll still hear each other just fine, until one of two things happens: We go on either side of a hill or far enough to be beyond the horizon, and then abruptly stop hearing each other, or the signal will fade in intensity until the background noise is louder.
If we get to that point where the signal is weak but still receivable, increasing output power of the transmitter, or switching to a directional antenna might help. People tend to think antenna gain is some magic that makes the radio louder, but it’s not. A high gain antenna does the same thing that cupping your hand behind your ear or around your mouth does; it puts more of the energy that would have gone in different directions in the direction you need.
Without getting too far into antenna theory, I will say that yes having two antennas near each other can cause them to interfere with each other. “Wrestle for the same radio waves” isn’t the way I would describe it. Antennas resonate with radio waves, it’s like a tuning fork, if you play the note the tuning fork is tuned to, the tuning fork will start to vibrate and emit its own sound. If two antennas are quite close together, this can cause destructive interference. You can use the same principle to construct a high gain antenna; look up how yagi antennas work for more details.
If you don’t mind a followup question, what’s happening when a signal clears up if you touch or just hover near an antenna?
That can be for a few reasons…
In some cases you’re tuning (or detuning) the antenna capacitively.
On other cases, like if your tv gets interference when you’re standing in part the room, there may be standing waves causing interference, as the rf is bouncing around your room.
To further your point, theorically, there is a voltage potential between any two objects. That’s the capacitance. Better conductor, for the same surface area, create a bigger potential.
So when you tune/detune a signal with your presence near the antenna, it is because you are close enough to the antenna that the potential between you and the antenna affects the filter of the signal.
IF’s might heterodyne
