This article reports on a new class of broadband and fully 3-D printed E-plane coax-to-waveguide transition and a monolithically 3-D printed waveguide magic-T based on the transition. The transition is constructed by a section of air-filled rectangular coaxial transmission line (TL) that is placed between two broadband coax-to-waveguide probe transitions. It is used to interconnect the magic-T's sum port and the waveguide T-junction. The incorporation of the transition reorients all the waveguide arms of the magic-T into the E-plane. Some X-band prototypes of the proposed transition and the magic-T are designed and implemented. Polymer-based additive manufacturing and copper electroplating techniques are employed to monolithically fabricate each prototype. The transition and the magic-T exhibit broadband and low-loss characteristics from 8.2 to 12.4 GHz with the measured performance well matched with the simulations. In addition, the power handling capability (PHC), including the peak PHC (PPHC) and the average PHC (APHC), of the magic-T is evaluated by simulations, showing that the proposed magic-T could handle 100 W of APHC.

This article presents a comprehensive active N + 4 coupling matrix approach for the design of integrated filter-amplifier. The feedback between gate and drain, which is neglected in a previous work, is considered, which improves the accuracy of the coupling matrix model for transistors. More importantly, the relationship between the coupling matrix and the noise figure is also established, which extends the coupling matrix method to tackle noise-related circuit functions. Substrate integrated waveguide (SIW) filters are used to implement an integrated X-band filter-amplifier design and to validate the design approach in terms of return loss, gain, and noise. Compared with rectangular waveguide, SIW is utilized for its appealing advantages, such as lower production cost, easier fabrication, and most importantly easier integration with active components. A second-order filtering circuit is applied to simultaneously match the input and output of the transistor. The integration reduces the losses from the intermediate networks in conventional designs, which is particularly important when the frequencies go higher. The measurements agree very well with the simulations in terms of S-parameters, gains, and noise figures.

A 290-310 GHz Schottky diode based sub-harmonic mixer with integrated, low loss, impedance matching waveguide cavity filters is presented in this paper. This mixer was designed for use in a 300 GHz communication system with a 20 GHz intermediate frequency (IF) band centred at 15 GHz. Image rejection of the 260-280 GHz lower sideband (LSB), as well as impedance matching, was achieved using an integrated 3rd order filter in the RF waveguide. The conventional coupling matrix was used to design the filter even though the impedance presented to the RF port was complex and frequency dependent. The mixer was measured to have: (1) Single sideband (SSB) conversion loss of 9-10 dB across the upper sideband (USB), with a mixer noise temperature of 2000-2600 K. (2) A return loss at the RF port better than 12 dB, with three filter reflection zeroes (poles) distinguishable. (3) A sideband rejection ratio (SBR) from 13 to 25 dB, demonstrating the RF filter's excellent performance in terms of impedance matching and filtering.

The design and performance of a WR-5 band 135-150-GHz Schottky diode-based frequency tripler which uses waveguide resonator filters for low loss impedance matching is presented in this paper. The filters used in this paper provide filtering, impedance matching, and microstrip (MS) to waveguide transitions in one structure. The matching optimization is achieved by scaling the external quality factors and adjusting the resonance frequency of the filter cavities. This approach transfers most of the tripler's matching networks from MS circuitry to lower loss rectangular waveguide resonators. This is desirable and useful in particular for submillimeter wave and terahertz frequencies. The device presented is a 47.5 to 142.5 GHz biasless frequency tripler with a 15-GHz output bandwidth. The tripler was measured to have a conversion loss of 13.1-14 dB across the band, at an input power of 17 dBm. The measured S ₁₁ at the input port is better than 15 dB and all the reflection zeros from the filter resonances are distinct. The good agreement between measurements and simulations verifies the accuracy of the filter-based design approach.

A novel waveguide step‐twist integrated with a bandpass filter is presented in this Letter. The twist is composed of four equally rotated cavities to achieve polarisation rotation and filtering functionalities simultaneously. Such step‐twist can achieve a significant reduction in size and weight. The design is demonstrated at Ka‐band using waveguide technology and is fabricated using a stereolithography apparatus 3D printing together with metal plating. The device is designed to have a centre frequency of 32 GHz and a bandwidth of 1 GHz. The measured result shows good agreement with simulations, with a measured average insertion loss of 0.84 dB and a return loss better than 15 dB across the passband.

This article presents a waveguide with a pair of E -plane bends and two waveguide bandpass filters (BPFs) which operate in WR-3.4 band (220–330 GHz). These devices are fabricated by a micro metal additive manufacturing (M-MAM) technology on copper in one piece. Both filters are fifth order and operate at a center frequency of 280 GHz with a bandwidth of 8 GHz. Cylindrical resonators are employed for filter design. The standard feed waveguides are designed in bend structures, facilitating the measurements. The M-MAM technology is a layer-by-layer additive manufacturing process constructing the waveguide devices in five layers. Since the layout of the devices has a strong impact on the electrostatic field distributions and hence the electroforming quality, both full-wave electromagnetic (EM) simulations and electrostatic analysis are simultaneously considered in the device design. It eases the subsequent electroforming and polishing processes, effectively improving the performance of the devices. The insertion losses and return losses of the measured filters are lower than 1.65 dB and better than 15 dB. The center frequency shifts are less than 0.3%. The excellent results attribute to the delicate co-design method between EM and electrostatic analyses encountered both in the filter design and in the additive manufacturing process.