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A new kind of contactless electromagnetic bandgap (EBG) structure in the form of interdigital-pin bed of nails is introduced for the first time in this paper. It consists of two metal plates with interdigital-pin bed of nails face to face with each other, where each pin is surrounded by four pins on the other plate. The working mechanism of the interdigital-pin contactless EBG structure is suppressing the modes supported by the parallel plate waveguide (PPW) by loading interdigital pins inside the PPW. The advantage of the interdigital-pin lattice is there is a significant pin gap increase. This lattice makes the minimum pin gap that could be processed by the machining center, after assembling, reduced from the diameter of the milling clutter to its radius. It provides a way to process EBG structures at higher frequency band with the same milling cutter. The cases the pins allocated between the two plates in a random manner are also studied. Compared to its traditional counterpart, the stopband is stable with a small variation. A W-band groove gap waveguide (GGW) prototype with interdigital-pins and a Ka-band GGW with randomly allocated pins are designed, manufactured, and tested. The measured results agree well with the simulation.

This letter presents the development of a compact 220 GHz heterodyne receiver module for radars application in which a novel low pass wide stop band intermediate frequency (IF) filter is integrated. The planar Schottky anti-parallel mixing diode based subharmonic mixer (SHM) is used as the receiver’s first stage. The diode is flip-chip mounted on a 50 μm thick quartz substrate. The accurate modeling of the self and mutual inductance of the diode’s air-bridges are discussed. The measured conversion loss (CL) of the SHM has a minimum value of 6.2 dB at 210.5 GHz, and is lower than 8.4 dB in the frequency range 209.4–219.6 GHz with a 10 mW input power from a local oscillator (LO). The LO chain consists of a 110 GHz passive tripler, two Ka-band amplifiers and a Ka-band active tripler. The tested minimum double side band (DSB) noise temperature of the integrated 220 GHz heterodyne receiver is 725 K at 205.2 GHz and lower than 1550 K in the frequency range 199–226 GHz.

This paper proposes a novel sub-harmonic mixing topology. Based on the proposed topology and the precise three-dimensional electromagnetic model of the Schottky barrier diode, a novel 183 GHz solid-state sub-harmonic mixer is designed and measured. By adding a compact low-pass filter near the ground of the mixer&rsquo, s circuit, the effect on the mixer&rsquo, s RF performance of the random error of the conductive adhesive in assembling is effectively decreased. The test results show that the optimal single-sideband conversion loss of the mixer is 8.1dB@183GHz when the local oscillator signal is 4mw@91GHz. In the RF bandwidth from 173 GHz to 191 GHz, the single-sideband conversion loss is less than &minus, 10.6 dB. At the same time, the RF port return loss is less than 9.8 dB.

Based on a W-band high-power source, two schemes are proposed to realize a 335 GHz frequency multiplier source. The first scheme involves producing a 335 GHz signal with a two-stage doubler. The first doubler adopts two-way power-combined technology and the second stage is a 335 GHz doubler using a balanced circuit to suppress the odd harmonics. The measured output power was about 17.9 and 1.5 dBm at 167.5 and 335 GHz, respectively. The other scheme involves producing a 335 GHz signal with a single-stage quadrupler built on 50 &micro, m thick quartz circuit adopting an unbalanced structure. The advantage of the unbalanced structure is that it can provide bias to the diodes without an on-chip capacitor, which is hard to realize with discrete devices. The measured output power was about 5.8 dBm at 337 GHz when driven with 22.9 dBm. Such 335 GHz frequency multiplier sources are widely used in terahertz imaging, radiometers, and so on.

Wideband traveling wave PIN Diode switches and attenuators are proposed. The switches and attenuators consist of three shunt PIN diodes, six radial stubs, bias circuit and DC return circuit. Wide bandwidth is achieved with six different radial stubs as reflective load of the diodes. The stubs work as short circuit to the diodes at different frequency points for broad bandwidth. For the Single pole single throw (SPST) switch, the lowest measured Insertion loss (IL) is 0.75dB and lower than 2.0dB in 85-105GHz, and its isolation is better than 21.3dB. As a Voltage-controlled variable attenuator (VCA), typical attenuation range is 23dB and attenuation fluctuation is lower than 5dB in 85-105GHz.

A 320–356GHz fixed-tuned frequency doubler is realized with discrete Schottky diodes mounted on 50µm thick quartz substrate. Influence of circuit channel width and thermal dissipation of the diode junctions are discussed for high multiplying efficiency. The doubler circuit is flip-chip mounted on gold electroplated oxygen-free copper film for grounding of RF and DC signals, and better thermal transportation. The whole multiplying circuit is optimized and established in Computer simulation technology (CST) suite. The highest measured multiplying efficiency is 8.0% and its output power is 5.4mW at 328GHz. The measured typical output power is 4.0mW in 320–356GHz.

This paper presents development of low conversion loss fundamental mixers. Appropriate reflector networks are employed to provide proper terminations for operation frequencies and other undesired frequency mixing components in the designed Ka-band single-ended mixer and X-band single balanced mixer. Quantitative analysis of the mixer terminations is presented. Syntheses of the input and output reflector networks are optimized for the mixers. The measured conversion loss of the X-band mixer is $6.4\pm 0.7\mathbf{dB}$ from 10 to 11.5GHz, the lowest conversion loss is 5.67dB at 10.6GHz. RF-IF port isolation is better than 27dB, LO-IF port isolation is higher than 24dB and LO-RF port isolation is better than 14dB. To the Ka-band mixer, the lowest measured conversion loss is 3.52dB at 32.2GHz, the conversion loss is flat and less than 5.68dB from 29 to 34GHz.

Contactless waveguide flange is a novel structure to prevent leakage of electromagnetic wave when it propagates across the waveguide flange. The main advantage of contactless waveguide flange is electrical contact of the connected waveguides is not required as long as the gap between the adjacent flanges does not exceed the maximum permitted distance. Therefore, relative motivation or rotation of the contactless connected waveguides is possible. The contactless waveguide flanges have been reported are all planar. A cylindrical contactless flange is first proposed. Then, a novel flexible rectangular waveguide is proposed based on it. A Ka-band prototype is successfully designed and manufactured. The prototype consists of two bendable contactless flange joints. The maximum bending angle of each joint is limited to ±8° to maintain the return loss performance. The number of joints can be easily increased if larger bending angles are needed. The insertion loss and return loss at different bending angles are measured. The measured insertion loss is better than 0.7 dB from 26 to 37 GHz, and is better than 1.8 dB from 37 to 40 GHz. The measured return loss is 15 dB except frequencies around 37.5 and 40 GHz.

To effectively reduce the requirement of Local Oscillator (LO) power, this paper presents the design and measurement of a biased sub-harmonic mixer working at the center frequency of 0.67 THz in hybrid integration. Two discrete Schottky diodes were placed across the LO waveguide in anti-series configuration on a 50 &mu, m thick quartz-glass substrate, and chip capacitors were not required. At the driven of 3 mW@335 GHz and 0.35 V, the mixer had a minimum measured Signal Side-Band (SSB) conversion loss of 15.3 dB at the frequency of 667 GHz. The typical conversion loss is 18.2 dB in the band of 650 GHz to 690 GHz.

A 75–110 GHz low conversion loss (CL) eighth harmonic mixer is realized for low cost 94 GHz receiver front-ends. The mixing diodes are realized by GaAs foundry of Nanjing Electronic Devices Institute (NEDI) and its 3-D model is analyzed for impedance calculation of RF, LO, IF port. Wide band-stop filters and phase shift networks for RF and idle frequency signals recycling are designed with optimum load impedance for low CL. The measured CL of the mixers is lower than 28 dB, 18 dB, 16.5 dB in 75–110 GHz, 87–104 GHz and 90–100 GHz, respectively. The lowest tested CL is 14.7 dB at 94 GHz. The mixers are successfully applied in miniature and low cost 94 GHz receiver systems.