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This study investigates the integration of reduced graphene oxide (rGO) films as ground plane in miniaturized RF/mm-wave systems for advanced thermal management applications. Traditional methods such as copper-based heat spreaders struggle to handle the increased power and tighter integration requirements of modern day RF/mmWave packaging. Due to rGO’s exceptionally high in-plane thermal conductivity (∼1100 W/mK), when compared with copper (∼400 W/mK), rGO emerges as a compelling candidate for thermal management in RF electronic packaging. This study investigates the use of rGO to form a ground plane in RF and microwave electronics, evaluating its performance through meticulous transmission line simulations and measurements. Our findings reveal that rGO ground planes exhibit high signal integrity, with an average loss of about 1 dB at 10 GHz and around 2 dB up to 26 GHz, comparable to the performance of traditional copper ground planes. These results indicate that rGO is a promising material for RF and microwave circuits, especially in applications requiring enhanced thermal management and mechanical flexibility. 

This paper presents a fully 3D-printed wideband mm-wave beam-steering antenna concept capable of performing wide-angle electronic beam-steering by making use of zigzagged lens antenna subarrays (LASs) with curved focal surfaces. The concept is demonstrated through the design and realization of a 38 GHz antenna consisting of L=4 dielectric slab waveguide (DSW) lenses each fed with structurally embedded M=6 TEM horn antennas, which can effectively reduce the required number of phase shifters (PSs) from N=M×L=24 to L=4 . It is demonstrated that the joint utilization of zigzagged LAS and curved focal surfaces with structurally integrated TEM horn antennas, all enabled through the design flexibilities offered by the emerging additive manufacturing (AM) technology, improves the realized gain, side lobe level (SLL), and beam-steering range in comparison to the earlier versions realized with planar focal surfaces. Specifically, the antenna exhibits a simulated realized gain of 16.5 dBi with an H-plane beam-steering range exceeding ±45° and a half-power beamwidth (HPBW) of 4.5° while maintaining an SLL below –9.3 dB across the entirety of the scan range. Measurements taken with the manufactured antenna prototype show excellent agreement with the performance obtained from full-wave simulations. 

Laser enhanced direct print additive manufacturing (LE-DPAM) technology has recently been demonstrated to achieve success in packaging of antennas with phase shifters to realize passive phased antenna arrays (PAAs). Utilizing LE-DPAM for PAAs operating in mm-wave bands brings out new challenges that need to be addressed. These challenges are associated with smaller antenna and feature sizes needed for mm-wave band operation, necessity of active circuits for amplification, and number of pads, pad size and pad locations of mm-wave beamformer IC packages. This paper presents our initial progress in scaling LE-DPAM based packaging of PAAs into the mm-wave band operation through consideration and demonstration of discrete components (i.e. antenna array elements and beamformer ICs) that form the PAA structure. Specifically, a stand-alone, passive, 2×2 LE-DPAM based 26 GHz antenna subarray is investigated for its performance. In addition, a 24.5 GHz – 27 GHz beamformer IC is packaged in a stand-alone test article using LE-DPAM and investigated for its mm-wave performance and thermal aspects.