Millimeter-Wave Active Array Antennas Integrating Power Amplifier MMICs through Contactless Interconnects
Doctoral thesis, 2021

Next-generation mobile wireless technologies demand higher data capacity than the modern sub-6 GHz technologies can provide. With abundantly available bandwidth, millimeter waves (e.g., Ka/K bands) can offer data rates of around 10 Gbit/s; however, this shift to higher frequency bands also leads to at least 20 dB more free-space path loss. Active integrated antennas have drawn much attention to compensate for this increased power loss with high-power, energy- efficient, highly integrated array transmitters.
Traditionally, amplifiers and antennas are designed separately and interconnected with 50 Ohm intermediate impedance matching networks. The design process typically de-emphasizes the correlation between antenna mutual coupling effects and amplifier nonlinearity, rendering high power consumption and poor linearity. This research aims to overcome the technical challenges of millimeter-wave active integrated array antennas on delivering high power (15–25 dBm) and high energy efficiency (≥25%) with above 10% bandwidth.

A co-design methodology was proposed to maximize the output power, power efficiency, bandwidth, and linearity with defined optimal interface impedances. Contrary to conventional approaches, this methodology accounts for the correlation between mutual coupling effects and nonlinearity. A metallic cavity-backed bowtie slot antenna, with sufficient degrees of freedom in synthesizing a non 50 Ohm complex-valued optimal impedance, was adopted for high radiation efficiency and enhanced bandwidth. To overcome interconnection’s bandwidth and power loss limitations, an on-chip E-plane probe contactless transition be- tween the antenna and amplifier was proposed. An array of such antennas be- comes connected bowtie slots, allowing for wideband and wide-scan array performance. An infinite array active integrated unit cell approach was introduced for large-scale (aperture area ≈100 λ2) active array designs.

The proposed co-design flow is applied in designing a Ka-band wideband, wide scan angle (±55°/±40°) active array antenna, consisting of the connected bowtie slot radiator fed through the on-chip probe integrated onto the output of a class AB GaAs pHEMT MMIC PA. The infinite array performance of such elements is experimentally verified, presenting a 11.3% bandwidth with a peak 40% power efficiency, 28 dBm EIRP, and 22 dBm saturated power.

power amplifier


Integrated active antenna

contactless transition

HC3, Hörsalsvägen 14, Chalmers
Opponent: Prof. Dr. Hua Wang, Department of Information Technology and Electrical Engineering, Eidgen ossische Technische Hochschule Zürich (ETH Zurich), Switzerland


Wan-Chun Liao

Chalmers, Electrical Engineering, Communication, Antennas and Optical Networks

A Ka-Band Active Integrated Antenna for 5G Applications: Initial Design Flow

2018 2nd URSI Atlantic Radio Science Meeting (AT-RASC),; (2018)

Paper in proceeding

A Directly Matched PA-Integrated K-band Antenna for Efficient mm-Wave High-Power Generation

IEEE Antennas and Wireless Propagation Letters,; Vol. 18(2019)p. 2389-2393

Journal article

Antenna Mutual Coupling Effects in Highly Integrated Transmitter Arrays

14th European Conference on Antennas and Propagation, EuCAP 2020,; (2020)

Paper in proceeding

Power Efficiency and Linearity of Highly Integrated Transmitting Array Antennas

15th European Conference on Antennas and Propagation, EuCAP 2021,; (2021)

Paper in proceeding

Co-Design and Validation Approach for Beam-Steerable Phased Arrays of Active Antenna Elements with Integrated Power Amplifiers

IEEE Transactions on Antennas and Propagation,; Vol. 69(2021)p. 7497-7507

Journal article

A fast expansion of 5G is happening globally, driven by the evolution of mobile networks demanding very high data rates and very low latency. The advance in cellular networks will reshape our society and our ways of living, enabling usage scenarios such as self-driving cars, augmented reality, and smart cities to simplify our lives. 

The ongoing transformation of mobile technologies gives rise to challenges beyond the capabilities of modern sub-6 GHz technologies. Millimeter waves allow for data rates in the order of 10 Gbit/s. However, the Friis Transmission Equation shows that the shift to higher frequencies leads to more signal attenuation; therefore, sending a wireless signal in millimeter-wave bands is more challenging than in sub-6 GHz bands. Technological solutions, such as energy-efficient active integrated arrays with high antenna gain and output power, are required to compensate for the increased attenuation associated with millimeter waves.

An interdisciplinary amplifier-antenna co-design methodology is motivated to overcome design challenges in wideband active integrated array antennas requiring low power consumption.  It accounts for the correlation between electromagnetic coupling effects and amplifier nonlinearity that is typically de-emphasized in an amplifier-centered or antenna-centered conventional design methods. Additionally, an infinite array active antenna design method is incorporated in the co-design approach to facilitate large-scale active array designs for optimized energy efficiency, bandwidth, output power, and scan range. This methodology has been applied in designing a 28 GHz active integrated array antenna that has been verified experimentally. The potential application domains of this research are array antenna designs for space-borne satellite communications, defense applications, and next-generation terrestrial cellular communications.

Areas of Advance

Information and Communication Technology

Subject Categories


Electrical Engineering, Electronic Engineering, Information Engineering

Other Electrical Engineering, Electronic Engineering, Information Engineering



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5061



HC3, Hörsalsvägen 14, Chalmers


Opponent: Prof. Dr. Hua Wang, Department of Information Technology and Electrical Engineering, Eidgen ossische Technische Hochschule Zürich (ETH Zurich), Switzerland

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