A Multichannel THz Detector Using Integrated Bow-Tie Antennas

This paper presents a kind of a multichannel THz detector using lens-based bow-tie array. A hyperhemispherical silicon lens is employed to provide a focal plane; 8 bow-tie elements are arranged on the focal plane with careful design to show a performance of broadband, high gain, well compact, and easy assembling. These characteristics of the detector are preferred for detecting weak THz signal. Measured far field shows that the radiation pattern of each element is shifted angularly, by ≈9°, which can be used for THz imaging. Tested responsivity of the detector shows a good spectral performance from 260 to 400 GHz: respective values were ≥220 V/W, and the best NEP is achieved at about 60 pW/. Besides that, the proposed antenna has advantages of simple structure, easy fabrication, and low cost

Heterostructure barrier Varactor Frequency Multipliers: Materials, Devices and Circuits

The Heterostructure Barrier Varactor, HBV, diode is used in frequency multipliers at millimetre and sub millimetre wavelengths. Owing to its symmetrical properties only odd harmonics are generated, this greatly simplifies the design of frequency triplers and quintuplers. We report on new InP based material and device designs for planar, whisker contacted, and novel pillar structure HBVs. We present design methods with measured and simulated results. We also report on a new waveguide frequency tripler where HBV diodes are embedded in a microstrip environment together with the matching network for the fundamental and the third harmonic. Simulated results are presented for this new circuit topology, which is highly suitable for system integratio

A 100-GHz HBV frequency quintupler using microstrip elements

A new quintupler concept using a heterostructure barrier varactor (HBV) has been fabricated and measured. The multiplier consists of a quartz circuit mounted in a full height crossed waveguide block, and hence uses a mixture of waveguide components and microstrip elements. The embedding impedance for the fundamental frequency is provided by tuneable backshorts, whereas conventional microstrip circuit elements are used for impedance matching for the third and fifth harmonic. This topology is highly suitable for monolithic integration, and a peak conversion efficiency of 4.9 % was measured at 102.5 GHz with an input power of 13 dBm

Thermal constraints for heterostructure barrier varactors

Current research on heterostructure barrier varactors (HBVs) devotes much effort to the generation of very high power levels in the millimeter wave region. One way of increasing the power handling capacity of HBVs is to stack several barriers epitaxially. However, the small device dimensions lead to very high temperatures in the active layers, deteriorating the performance. We have derived analytical expressions and combined those with finite element simulations, and used the results to predict the maximum effective number of barriers for HBVs. The thermal model is also used to compare the peak temperature and power handling capacity of GaAs and InP-based HBVs. It is argued that InP-based devices may be inappropriate for high-power applications due to the poor thermal conductivity of the InGaAs modulation layers