In this paper, a balanced-to-balanced power divider is proposed, for the first time, with arbitrary power division, which can be regarded as the balanced form of a Gysel power divider. The constraint rules are provided for its mixed-mode and single-ended S-parameters. The six-port network is analyzed by simplifying it to two-port networks with other ports matched at the central frequency. Its critical characteristic impedances are then calculated analytically by our derived equations according to the desired differential-mode power division ratio. The maximum achievable power division ratio is 1:4.69² when the characteristic impedances are limited within the realizable range of 20-120 Ω. The impacts of several freely selected design parameters on the operating bandwidth are explored numerically. A prototype is realized by microstrip lines and lumped resistors with the power division ratio of 1:3². The balanced-to-balanced performances of unequal power division, low differential-mode insertion loss, good suppression of common-mode noises, and mode conventions have been demonstrated by the simulated and measured results of the balanced-to-balanced power divider prototype.

Substrate integrated coaxial line (SICL) is a kind of planar transmission line, which can guarantee the propagation of transverse electromagnetic mode wave within a wide band. In this paper, a multichannel SICL array with coaxial lines placed in both vertical and horizontal directions is proposed for high-speed parallel data transmission. The adjacent channels of the SICL array share outer conductors for high-density integration. Moreover, the outer conductor is enhanced by metal fence to suppress the crosstalk between adjacent channels of the SICL array. In addition, a quasi-coaxial transition is designed for the proposed SICL array. A systematical design procedure is given to determine the physical dimensions of SICL array with transitions. The SICL array has flat group delay so that data can be transmitted without significant phase distortion. It is suitable for high-density integration and high-speed data transmission due to the low crosstalk and high bandwidth. To verify the advantage of the proposed SICL array, a 15 x 3 channel prototype is designed and fabricated in low temperature co-fired ceramic. The measured S-parameters agree well with the simulated results. The maximum bandwidth of a single channel of the SICL array is up to 56 GHz and the coupling of adjacent channels in the SICL array is less than -30 dB. Data rate of 30 Gb/s is measured for each channel with good eye diagram and low bit error rate, and hence, a total 1.35-Tb/s data rate can be achieved with the proposed 15 x 3 channel SICL array.

A new type of half-mode substrate integrated waveguide (SIW) periodically loaded with different lumped elements and structures is proposed in this paper. The propagation constants, Bloch impedances, and voltage distributions of the Floquet TE-modes are all characterized by solving the eigenvalues of the generalized transmission matrix of a single period. Several typical capacitor-loaded, inductor-loaded, corrugated, and electromagnetic-bandgap (EBG)-loaded half-mode SIWs were fabricated to demonstrate their modal dispersion behavior. The measured and simulated S -parameters, group delays, and simulated electric field distributions in these novel structures are presented, with good agreements obtained for all samples. In particular, their unique controllable cutoff frequencies, multiple bandgaps, and separated monomode regions are also illuminated numerically and experimentally. To further show their applications, a tunable phase shifter is developed using a varactor-loaded structure, with its 3-dB bandwidth of 50% and a maximal tunable range of 88°. In addition, a bandpass filter based on EBG-loaded half-mode SIW is also realized and presented with its special characteristics. It demonstrates that the filter has a sharp upper slope side and a good performance of spurious suppression.

In recent years, there has been great interest in millimeter-wave (mmwave) and terahertz (THz) technologies due to an increasing demand for ultrahigh data transfer rate. Two novel solutions, i.e., antenna on chip (AoC) and antenna in package (AiP), have been proposed for the development of highly integrated radio and radar systems [1]-[5]. To measure the antenna characteristics of AoC and AiP, a reliable probe-based mm-wave/THz antenna measurement setup became essential. Over the last 20 years, the world has witnessed the prosperous development of various mmwave/THz antenna measurement setups, most of which can be divided into two types, i.e., probe-station and quasi-in-air based. The former type has a feature that allows the testing equipment to be compactly established on a large metal stage, which has been widely used for near-field based and as part of the farfield-based setups [6]-[10]. The antenna under test (AUT) is maintained on a wafer chuck placed on the stage and thus, only the radiation pattern in the upper half-space is measurable due to the metal stage obstruction. The latter type reduces the defect by using an extended supporting structure to hold the AUT in midair away from the stage so that the radiation patterns in both the upper and lower half-spaces are measurable. Many setups of this type measure antennas at far-field distances, and some of them are also compatible with near-field testing. Compared to probe-station based, quasi-inair based takes up much more space and is less compact.

In this article, the design and implementation of two 28-GHz millimeter-wave on-chip high selectivity bandpass filters with coupled dual-behavior resonators are proposed. The proposed bandpass filters consist of coupled dual-behavior resonators with open/shorted stubs. Two and three out-of-band transmission zeros can be realized for the two bandpass filters. Two on-chip millimeter-wave bandpass filters are designed and fabricated for verification. The measurement results show that the insertion losses are both less than 2.2 dB at the center frequency. The sizes of the designed filters are 2.556 mmx 1.23 mm and 3.155 mmx 1.47 mm, respectively, including the pad.

A new differential microstrip feeding method is proposed for dielectric resonator antenna (DRA) and array with low permittivity. Two parallel microstrip lines with differential signals are placed underneath the rectangular DRA to excite its fundamental TE _δ11 ^x mode. A single-port DRA element is first designed with a balun. The measured -10 dB bandwidth is achieved to be 22% around 2.4 GHz, and the in-band realized boresight gain is around 6 dBi. Then, a 2 × 2 differentially fed DRA array is developed, combining series and parallel feeding networks. An 18.7% bandwidth and an average gain of 12.3 dBi are achieved. The effectiveness of our proposed feeding method has been demonstrated by the good agreement between the measured and simulated results.