In this communication, a new kind of dual-band hybrid dielectric resonator antenna (DRA) with its array design and extended dual-polarized version is presented for 5G millimeter-wave (mm-Wave) applications. The hybrid antenna which integrates three types of resonators of strip, slot, and DRA can generate four resonances in 28 GHz and 39 GHz frequency bands. In this design, the strip and slot modes are used to cover the lower frequency band of 26.41 - 30.42 GHz, while the TE111 and TE131 modes of the DRA are employed to cover the upper frequency band of 36.05 - 40.88 GHz. It shows that the 5G mm-Wave bands of n257 and n260 can be covered simultaneously. It should be mentioned that our proposed hybrid antenna has a compact size of 0.34 λ ₀₁ ×0.36 λ ₀₁ ×0.1 λ ₀₁ (λ ₀₁ means the free-space wavelength at 28 GHz). Based on the compact size of the antenna element, a 1×5 antenna array with the capability of beam steering is designed and simulated. Wide steering angles of ±50° and ±40° can be obtained at 28 GHz and 39 GHz frequency bands, respectively. Further, an extended dual-polarized antenna configuration is also described and measured that provides similar two port impedance and radiation performance with the single port counterpart.

Bandpass power amplifiers (PAs) are typically implemented by a cascade of second-order topologies. To achieve a wide and flat passband response, the number of resonators must be increased, which leads to large size, high loss and low efficiency, especially at high frequencies. In this paper, a wideband Class-F⁻¹ PA based on a microstrip multimode bandpass impedance transformer (BPIT) is proposed. The modified quad-mode BPIT operation enables the creation of multiple transmission poles using only a single resonator, thus simultaneously achieving a flat wideband response in a small size. In addition, the drain bias and input feed line of the BPIT are arranged to satisfy the harmonic-impedance requirement of the Class-F⁻¹ amplifier. Two PA prototypes have been designed, fabricated, and measured, which exhibit desirable filtering characteristics centered at 3.5 and 3.6 GHz for 5G applications. The fabricated dual- and quad-mode circuits demonstrate large-signal gains of 11.5 dB and 12.6 dB, maximum power added efficiencies (PAEs) of 67.4% and 66.3%, respectively and, with output powers greater than 38.5 dBm. For operation with a PAE larger than 60%, the PAs achieve bandwidths of 150 and 250 MHz, respectively.

Post-matching network (PMN) dominates broadband Doherty power amplifier (DPA) design, but at the cost of large footprint. This brief presents a PMN-free, compact and broadband DPA based on dual-mode impedance transformer (IT) which can simultaneously realize a complex-to-real conversion at two frequencies. The conversion ratio of the IT is significantly increased while its fluctuation is reduced after collaborating a short drain bias. The dual-mode ITs are used as the output matching networks in the carrier and peaking paths. An out-of-phase 2nd harmonic injection path is constructed based on the inherent structure of the IT without additional bridge, resulting in enhanced saturated efficiency and output power at the upper band edge. A prototype circuit operating from 2.1 to 3.1 GHz is fabricated, and measured results show a 7-8.2 dB gain and 42.2-43.3 dBm output power at saturation. The 6-dB OBO and saturated efficiency is 42.3-52% and 60.4-67.7%, respectively. The area of the whole OMNs is only 19×37 mm2, indicating a significant size reduction, while the DPA’s performance is comparable with the PMN types.

In this paper, a novel defected ground structure (DGS) is proposed for lowpass filter (LPF) applications. The proposed structure exhibits wideband attenuation without increasing the circuit size, a...

This paper presents a novel dielectric-loaded strip resonator (DLSR) with coaxial-like characteristic, comprising a metal strip attached on the surface of a high-permittivity dielectric rod. The strip of traditional strip-loaded dielectric resonator only functions as the perturbation for tuning the dielectric resonator mode. In particular, the dominant mode of the proposed DLSR stems from the strip and works as a quasi-λ _g /4 resonator. It possesses very low resonant frequency with immense design freedom. The corresponding characteristics and frequency expressions of the strip mode are theoretically deduced and verified on the basis of the E-field distribution of the DLSR. For demonstration, a variety of single-ended inline filters are exploited using single-strip DLSRs with different deployments as well as the generation mechanism of transmission zeros is investigated. Furthermore, a simple modification with twin strips can serve for electrically small differential topology, highlighting the versatile design of the DLSR. Besides desirable differential-mode (DM) response, the differential DLSR filter manifests a large deviation between DM and common-mode (CM) frequencies, resulting in a satisfactory CM suppression in the DM passband. Good agreement between the simulation and the measurement validates the proposed methodology.

In this letter, a triple-mode bandpass filter based on a hollow silver-loaded ring-shaped dielectric resonator (RSDR) is designed by combining a dominant TE₀₁δ mode with a high-order degenerate HE₁₁δ pair. Because of the distinct E-field distribution, the frequencies of the HE₁₁δ pair can be pulled down and split using a loaded silver segment on top of a dielectric. Moreover, the silver segment has a negligible effect on TE₀₁δ and higher order TM₀₁δ modes, implying separation between a passband and adjacent interferers. To validate the methodology, a prototype silver-loaded RSDR is excited by the two L-type feeding probes to satisfy the requirements of coupling strengths for different modes.