The way I understand it, it requires the cyberware so it can mimic the Radar designator only. If you have natural Thermographic vision, then you can mimic the infrared spectrum. For you to mimic the designator, it has to be in a visual frequency that you can see.
Without the cyberware to mimic Radar, it would be akin to asking a person born blind to paint a rainbow.
Except, no other spell operates like this.
All the other spells base their limitations and targeting restrictions on the TARGET. Like, "Do you have line of sight?" or "Is the target the right category?" or "do I have to overcome OR?"
Not on the spell effect.
You can generate a wave of toxic slime, or listen to a conversation a mile away, or any number of other "it just works" effects, but somehow making a point radiate radio energy is restricted by whether or not you can perceive radio waves?
Heck, "Pulse" from Street Magic also creates an electromagnetic emission point, but somehow doesn't require a radar or other radio sense.
On a related note, as an illusion spell, you have to beat your own sensor's Object Resistance just for your sensor to even see the Designate effect.
Personally, I have no issues with the IDEA behind the spell. I don't even mind if the caster wants to modulate the strength of the designator dot in a pre-arranged pattern so the weapon sensor can tell it apart from other designator dots. But I would A) make it a manipulation spell instead of illusion (because it's ACTUALLY making a point of energy appear, not the illusion of one) and B) remove the restrictions needing special senses to cast the other variants, and possibly make each variant a separate spell.
-k