Antennas have been the driving force of the modern wireless industry for a long time, especially the antennas on PCBs. Microstrip patches, slot antennas, and F-antennas printed on substrates like FR4 give us reliable performance below 30 GHz. They let us tune frequency by adjusting patch dimensions and feed geometry. When we push into bands above 30 GHz, losses from copper roughness, substrate modes, and dielectric loss make PCB antennas inefficient and bulky.
To overcome the limits of PCB antennas, we are moving into two new approaches: Antenna-in-Package (AiP) and Antenna-in-Chip (AiC). In AiP, think of the antenna as part of the chip’s casing. It’s a miniature multi-layer printed-circuit board that just happens to have a bare RF chip solder-bumped into its centre and then gets shipped as a single surface-mount part. By printing or mounting the radiator onto the package substrate using low-loss organic laminates or ceramics, we ensure the materials do not absorb the signal. This lets us build small beam forming arrays and pack amplifiers, filters, and phase shifters right into the module.
AiC takes the idea all the way onto the silicon die. Here, we etch antenna shapes into the top metal layer of a CMOS chip. I’ve seen designers thicken that metal, add patterned ground shields beneath it, or insert artificial magnetic conductors to bounce more energy out of the lossy silicon. Some even place a thin cover (a superstrate) above the chip to help steer or focus the beam. Since silicon has a high permittivity and loses energy, it can’t get more efficient than a certain point.
AiC is an ultimate miniaturisation play, and AiP is the performance play. If you’re designing a smartphone or radar sensor today, AiP is the practical path, it gives you gain, beam-forming head-room and a cleaner PCB layout. You only pick AiC when absolute footprint has to be the size of the silicon itself, and you are pushing beyond 100GHz where antenna is only a few hundred microns long and PCB interconnects become impractical. To date, only a handful of functional antenna-on-chip prototypes have been demonstrated.
