Hui Chu

60-GHz LTCC Wideband Vertical Off-Center Dipole Antenna and Arrays

Wideband 60-GHz vertical off-center dipole antenna and its arrays on low-temperature cofired ceramic substrate are presented in this paper. The dipole antenna is designed using the off-center-fed technology to cover all the four channels defined in 60-GHz standards from 57 to 66 GHz. A 4 × 4 planar array is optimized to achieve a maximum gain of 15.6 dBi at 60 GHz and above 10.2 dBi in the passband, while a beam-steering array is optimized to give a 5-dB measured beamwidth wider than 80° at 60 GHz. Measured results indicate our designs meet the above requirements well and satisfy 60-GHz applications.

Wideband 60GHz on-chip antenna with an artificial magnetic conductor

A wideband 60-GHz on-chip antenna fabricated with a 0.18um CMOS process with an artificial magnetic conductor (AMC) is presented. A shield plane is patterned to create mesh and inserted between the on-chip antenna and the grounded lossy CMOS substrate. With this arrangement, a frequency selective surface is produced and the meshed shield plane provides high wave impedance over a certain bandwidth around 60 GHz. Meanwhile, the meshed shield plane behaves as an AMC and the reflected wave is in phase with the incident wave. Therefore, the loss induced by the CMOS substrate can be minimized. Both the AMC and the patch antenna are optimized to deliver a wideband operation covering 56–66 GHz. The size of the on-chip antenna including the AMC is 1.55mm by 1.55mm. Compared with the conventional on-chip antenna having a typical gain of −10dBi to −8dBi, the proposed on-chip antenna with an AMC can offer a gain of −2.5dBi to −1.5 dBi in the band. Measurement has verified the prediction.

135-GHz Micromachined On-Chip Antenna and Antenna Array

This paper presents the design, fabrication and “on-wafer” characterization of multi-membrane-supported and polymer-cavity-backed monopole antenna and 2× 1 patch antenna array operating in the 135-GHz frequency range. The designs were fabricated on two-layer benzocyclobutene (BCB) material membrane obtained by micromachining of the low resistivity silicon. The silicon material is removed underneath the monopole antenna to produce a cavity surrounded by metal and filled with polymer. This polymer filled cavity provides a better support to the membrane than conventional air cavity which is extremely important for practical applications. In the meantime, the higher synthesized effective dielectric permittivity of the BCB-polymer mixed region than BCB-air mixed one provides the possibility for compact antenna array designs. The proposed monopole antenna shows a measured impedance bandwidth from 124 to 136 GHz for |S11| less than -10 dB and maximum measured gain of 6.74 dBi at 131 GHz; while the 2×1 patch antenna array achieved a measured impedance bandwidth from 126.5 to 138 GHz for |S11| less than -10 dB and maximum measured gain of 8.66 dBi at 130 GHz.

A 3-D Millimeter-Wave Filtering Antenna With High Selectivity and Low Cross-Polarization

A three-dimensional (3-D) filtering antenna with features of high selectivity and low cross-polarization is proposed and experimentally verified in this communication. Thanks to the vertically 3-D integration, the high selectivity at either frequency sides of the filtering antenna is achieved by a novel cross-coupling scheme between in-band and out-of-band modes in a single cavity located in the lower substrate, while the low cross-polarization in the far-held is realized due to the symmetric feed and radiators on a cavity-backed dual-slot antenna at the upper substrate. In our design, the cavity-backed dual-slot antenna performs not only a radiator but also the last resonator of the bandpass filter (BPF). A prototype is demonstrated at Ka-band with a center frequency of 31.495 GHz and fractional bandwidth of 1.56%. Two radiation nulls [transmission zeros (TZs)] at either frequency band edges can be observed and a cross-polarization level lower than -30 dB is obtained.

A Millimeter-Wave Filtering Monopulse Antenna Array Based on Substrate Integrated Waveguide Technology

A millimeter-wave filtering monopulse antenna array based on substrate integrated waveguide (SIW) technology is proposed, manufactured, and tested in this communication. The proposed antenna array consists of a filter, a monopulse comparator, a feed network, and four antennas. A square dual-mode SIW cavity is designed to realize the monopulse comparator, in which internal coupling slots are located at its diagonal lines for the purpose of meeting the internal coupling coefficiencies in both sum and difference channels. Then, a four-output filter including the monopulse comparator is synthesized efficiently by modifying the coupling matrix of a single-ended filter. Finally, each SIW resonator coupled with those four outputs of the filter is replaced by a cavity-backed slot antenna so as to form the proposed filtering antenna array. A prototype is demonstrated at Ka band with a center frequency of 29.25 GHz and fractional bandwidth of 1.2%. Our measurement shows that, for the H-plane, the sidelobe levels of the sum pattern are less than -15 dB and the null depths of the difference pattern are less than -28 dB. The maximum measured gain of the sum beam at the center operating frequency is 8.1 dBi.

Broadband 60-GHz beam-steering vertical off-center dipole antennas in LTCC

Broadband 60-GHz vertical off-center dipole antenna and its arrays in low-temperature co-fired ceramic (LTCC) substrate are presented in this paper. The dipole antenna is designed using the off-center-fed technology to improve its bandwidth to cover the 60-GHz frequency band from 57 GHz to 66 GHz. A 4×4 planar array is optimized to achieve a maximum gain of 15.6 dBi at 60 GHz, while a beam-steering array using a low-cost Butler matrix is optimized to give a 5-dB measured beamwidth wider than 80° at 60 GHz. Measured results verified our prediction.

Wideband Self-Complementary Quasi-Yagi Antenna for Millimeter-Wave Systems

Novel wideband quasi-Yagi antennas, each featuring a self-complementary structure together with a triangular notch on the ground plane, are proposed. The optimized proposed antenna offers an improved relative bandwidth of 74%, gain of 4-8 dBi, and stable endfire radiation patterns within the passband. Good agreement between simulation and measurement is shown.

Compact Dual-Band Balanced SIW Bandpass Filter With Improved Common-Mode Suppression

The contribution of this letter is to propose a novel substrate integrated waveguide (SIW) dual-band balanced bandpass filter (BPF), which exhibits characteristics of compact size and improved common-mode (CM) suppression. Two diagonal resonant modes TE102 and TE302 in a square SIW resonator with symmetric field distributions provide the possibility to realize balanced inputs/outputs, dual-passband responses and the vertically stacked structure for compact size. Without affecting the differential-mode (DM) responses, a novel method of using slotlines etched on one broadside of either SIW resonators to shift the resonant frequency of CM away from the DM passband is also proposed, to realize a higher CM rejection for this BPF. Meanwhile, perturbation vias have been utilized to adjust the center frequency of the lower passband, while the higher passband can remain almost unchanged. A second-order prototype is designed for the demonstration. Good agreement between simulation and measurement has been observed in the measurement.

60-GHz LTCC dielectric resonator antenna array

A novel integrated dielectric resonator antenna (DRA) array, which permits the realization of wide impedance bandwidth as well as high and stable radiation gain, has been realized in LTCC technologies for V-band applications. Thanks to the relative high working frequencies, not only the feeding network, but also the dielectric resonator can be designed and fabricated using the same LTCC material of Ferro A6-M with εr = 5.9±0.002 at 60 GHz. The proposed 4 × 4 antenna array achieves a broad bandwidth of 24.9% and a gain up to 17.9 dBi.

Design of a Circularly Polarized Ground Radiation Antenna for Biomedical Applications

A ground radiation antenna with circularly polarized (CP) properties is proposed and studied for biomedical applications. A square ground with a small clearance is implemented in the proposed antenna. Reactive components are included to realize the impedance matching, as well as those requirements for the generation of CP waves. Simulations are conducted within a single-layer tissue model to evaluate the antennas performance. The proposed antenna exhibits a low profile, which is smaller than 1 mm even including two coating layers. The antenna also behaves good robustness to different implant depths and thicknesses of biocompatible coating, due to its wide axial ratio bandwidth ranging from 2.331 to 2.582 GHz. A prototype is fabricated and experimentally demonstrated in a solid skin-mimicking phantom. A measured impedance bandwidth of 621 MHz is achieved for the 2.4-2.48-GHz Industrial Scientific Medical band. Good agreement between simulation and measurement can be observed in the far-field measurement. The link budget is also evaluated, together with an exterior CP patch antenna.