Antennas are a fundamental component of modern communications systems to transmit and/or receive electromagnetic waves. Our lab has four technologies to design an antenna as follows:

  1. Antenna design
  2. MEMs technology
  3. Metamaterial
  4. Materials

Our lab has skills and knowledge to design many kinds of antennas such as air-lifted monopole, air-lifted patch antenna, lens antenna, monopole driven Yagi-Uda antenna and super wideband (SWB) antenna according to its applications. Also, matamaterials technique is applicable to design compact, dual band or high gain antenna. MEMs technology can be implemented to fabricate the designed antennas on flexible substrate for wearable applications, high dielectric material for compact antennas, Si substrate to integrate with CMOS devices and PCB board. Based on MEMs technology, the resonant frequency of the antennas is scalable from microwave to millimeter wave range.

Examples of antennas fabricated in our lab: (top) air-lifted or three-dimensional antennas (middle) flexible, compact, and super-wide-band antennas (bottom) metamaterial based antennas

Millimeter-wave Wireless Interconnects

This research shows a millimeter-wave wireless interconnect technology using Through Glass Via (TGV) disc-loaded antennas to realize high-speed data transmissions, the miniaturization of IC footprint, and the reduction of power consumption in 3D packaging. W-band (75GHz – 110GHz) TGV disc-loaded antennas have been designed and fabricated in a glass interposer layer and both omnidirectional and broadside radiation patterns have been achieved with a bandwidth of 29.23 % (Max.), a gain of 5.36 dBi (Max.) and an antenna efficiency of 97% (Max.) which is the highest antenna performance reported so far compared to ones reported in other literature.

Schematic of wireless intra-/inter chip communication using TGV disc-loaded antennas in 3D packaging

Microfabrication process used to fabricate the mm-wave inter/intra chip antennas.

This architecture has several unique merits: (1) Since low loss glass substrates are employed, very little power dissipation and RC delay occurs along the signal pathway for near and long distance data communications, and (2) both in-plane and out-of-plane millimeter wave wireless interconnects are enabled for high speed intra-/inter chip communications with clock synchronization capability among ICs using the unique interposer integrated antenna architecture and 3D microfabricaiton, and (3) a highly energy efficient data transmission rate of 1 pJ/bit would be realized using an advanced CMOS node.

Proposed TGV disc-loaded millimeter wave antennas integrated in the glass interposer layer: (left) a dual band architecture and (right) a multiple via feeding architecture to operate it in a patch mode

Non-magnetic/Ferromagnetic Multilayer Structures (Metaconductors)

In very high RF frequencies, namely 10GHz and above, conductor losses become a serious problem as a result of the skin effect. Cu/Ni and Cu/NiFe paired superlattice conductors featuring reduced radio frequency (RF) loss based on eddy current cancelling (ECC) have been studied. Also, the effects of various factors such as the width of the conductor and the individual layer thickness of the superlattice conductors have been studied for improved RF performance. Cylindrical and planar superlattice structures showing significantly lowered conduction loss and higher RF performance in the lower K-band have been fabricated on BCB and glass. Our lab has experience designing and fabricating these structures and aims to create entire RF devices, possibly IC devices as well, from this technology towards the goal of making the Internet of Things, 5G and beyond a reality.

Simulation of the current penetration in a traditional copper conductor (right) and the multilayer conductor (left). The current is extremely limited in the copper due to the skin effect, but with the eddy current canceling of the multilayer conductor, the current can flow through the bulk.

SEM images of the metaconductor inductors. The metaconductor layering is on the nanometer scale, so it is not visible at this scale.

(Left) Resistance versus frequency for metaconductors and traditional copper conductors. The copper conductor consistently increases in resistance with frequency, but the metaconductor begins to decrease in resistance once the eddy current canceling effect takes over. (Right) Circuit model and images of the measured structures.

Bridged CRLH

A modified design of the composite right/left handed (CRLH) unit cell showing all-pass and triple band response is demonstrated. By using an additional inductance which cross-couples the input and output ports of the conventional CRLH, a bridged CRLH unit cell (B-CRLH) is created. This allows additional right-handed (RH) wave propagation below the cutoff frequency of the conventional CRLH to DC. A triple band configuration is designed with a mid-frequency-LH band, a high-frequency-RH band, and the RH propagation below cut-off frequency.

(Left) Graphs of the simulated and measured performance of the bridged CRLH. (Right) Schematic and circuit model of the bridged CRLH unit cell.