We report on the use of slots for size reduction and tuning of folded patch antennas operating in the 5-6 GHz ISM band, with intended application in short-range wireless communications. Varying the slot length modifies the antenna electrical length, thus providing a new degree of freedom to control the antenna operating properties, and is the main novelty of our work. This technique was used for antenna tuning, input impedance control, and, very important, for antenna size reduction. Keeping the operating frequency at 5.7 GHz, application of slots allows an antenna size reduction close to 30%. Keeping the antenna dimensions constant, application of slots allows its tuning from 5.7 GHz down to 4.8 GHz and is potentially suitable for dynamic antenna reconfiguration.

Brain cancer is one of the deadliest forms of cancer due to limited treatment options and challenges in tumor differentiation during surgery. Current surgical assistance tools often face limitations in cost, accessibility, and precision. Millimeter-wave (mmWave) technologies have emerged as promising alternatives for real-time, non-invasive differentiation of healthy and cancerous brain tissues, leveraging their sensitivity to dielectric properties. This work presents the development and initial assessment of a mmWave measurement system designed to differentiate biological tissues based on their dielectric properties. As validation, various concentrations of isopropanol (IPA) in water were analyzed. Two setups, using reflection and transmission measurements, showed clear sensitivity to changes in dielectric constant, with the transmission setup demonstrating higher sensitivity.

This work reports on the use of bulk-micromachining technology to increase the efficiency of a folded shorted-patch antenna. This antenna was designed on two stacked wafers (glass bonded on high-resistivity silicon). The analysis was carried out using the HFSS FEM tool. It was shown that bulk-micromachining technology could be used together with HRS to increase the antenna efficiency by ~20 %. Also, it can be used to allow the use of low-resistivity silicon for antenna substrate. Furthermore, bulk-micromachining technology can be used as an option to tune or to select the antenna operating frequency.

This paper reports on design and fabrication options of an integrated folded shorted-patch chip-size antenna for applications in short-range wireless microsystems. The antenna is built using a stack of two adhesively bonded wafers with patterned metallization and through-wafer electrical interconnects. Different fabrication options based on via formation in glass and/or high-resistivity silicon substrates using excimer laser ablation or powder blasting are analyzed.

We report on the design of a novel, very small dualband antenna having double-folded structure and suitable for onchip integration in wireless sensor network nodes. The antenna operates simultaneously at 2.4 GHz and 5.7 GHz with a -10 dB return-loss bandwidth of 50 MHz and 170 MHz, respectively. A prototype fabricated on a 4003 RogersTM substrate (dielectric permittivity of 3.38) has dimensions of 6x8.5 mm2.

This paper presents the design and characterization of a patch antenna built on lossy substrates compatible with integrated circuits fabrication. Two different substrates were used for antenna implementation: high-resistivity silicon (HRS) and Corning Pyrex #7740 glass. The antenna prototypes were built to operate close to the 5 GHz ISM band where applications like HIPERLAN and IEEE802.11a are standardized. They operate at a center frequency of 5.705 GHz (HRS) and 5.995 GHz (Pyrex). The studied parameters were: substrate thickness, substrate losses, oxide thickness, metal conductivity and thickness. The antenna on HRS uses an area of 8 mm2, providing a 90 MHz bandwidth and ~0.3 dBi of gain. On a glass substrate, the antenna uses 12 mm2, provides 100 MHz bandwidth and ~3 dBi of gain.

High-resistivity polycrystalline silicon (HRPS) wafers are utilized as low-loss substrates for three-dimensional integration of on-chip antennas and RF passive components (e.g. large inductors) in wafer-level chip-scale packages (WLCSP). Sandwiching of HRPS and silicon wafers enables to integrate large RF passives with a spacing of >150 µm to the conductive silicon substrate containing the circuitry, while providing mechanical stability, reducing form factor and avoiding any additional RF loss. Antenna performance comparable to glass substrates and high quality factors for large spiral inductors (Q=11 at 1 GHz; 34 nH) are demonstrated. The HRPS substrates have high dielectric constant, low RF loss, high thermal conductivity, perfect thermal matching, and processing similar to singlecrystalline silicon.

High-resistivity polycrystalline silicon (HRPS) wafers are utilized as low-loss substrates for three-dimensional integration of on-chip antennas in wafer-level chip-scale packages (WLCSP). Sandwiching of HRPS and silicon wafers enables to integrate complex RF passives with a spacing of >150 µm to the conductive silicon substrate containing the circuitry, while providing mechanical stability, reducing form factor and avoiding any additional RF loss. A folded-patch antenna with dimensions of 2.5x2.5x1 mm3, operating at 5.7 GHz was analysed considering a 10 kΩ-cm HRPS wafer. The antenna has a –10 dB return loss bandwidth of 50 MHz and an efficiency of 58 %, a performance comparable to glass substrates.

This paper reports on fabrication and design considerations of an integrated folded shortedpatch chip-size antenna for applications in short-range wireless microsystems and operating frequency of 5.7 GHz. Antenna fabrication is based on wafer-level chip-scale packaging (WLCSP) techniques and consists of two adhesively bonded glass wafers with patterned metallization and through-wafer electrical interconnects. Two different fabrication options based on via formation in glass substrates using excimer laser ablation or powder blasting are presented.