We propose a dielectric rod waveguide antenna (DRW) integrated with a photomixer as a THz emitter. This represents a different approach as opposed to the classical solution of a substrate lens. Main goals are an inexpensive alternative to substrate lenses, reduction of both reflections on the semiconductor-air interface and scattering of terahertz-generated power into the substrate. A radiation pattern measured at 137 GHz is shown as a proof-of-concept. In order to increase radiated power, the improvement of the rod antenna is discussed. Finally, as an application example, evanescent coupling of the DRW into a high index whispering gallery mode resonator is shown.

This paper analyzes integrated components for ultra-broadband millimeter-wave wireless transmitters enabling the 5 G objective to increase the wireless data rates 10× to 100×. We have pursued the photonic-based approach to generate the millimeter-wave carrier (≈97 GHz in this paper) through photomixing. We have achieved up to 10 Gb s⁻¹ data rate using an OOK modulation format (to reduce latency) and either direct detection (DD) or coherent detection. We show that coherent detection enables a sensitivity improvement of 17 dB over DD. We also demonstrate in this work that such improvement can be achieved using as the transmitter a novel integrated antenna array—the self-complementary chessboard array. This avoids the use of complex coherent schemes at the receiver, enabling simple DD for ultra-broadband links.

Radiofrequency (RF) probes based on 50- $\Omega$ planar transmission lines play a key role in almost every stage of RF device development, establishing the physical contact between high-end instrumentation and the device. With the continuous downscaling of semiconductor technologies to reach into the millimeter-wave (30 GHz to 300 GHz) and Terahertz (300 GHz to 3 THz) bands and devices exhibiting broader frequency response, current RF probe technology is the Achilles heel for precise and repeatable measurements. Here we propose a novel RF probe technology based on near-field coupling of single-mode dielectric waveguide structures which according to our full-wave simulations provide an extremely broad frequency range covering from 0 Hz up to 340 GHz, the largest continuous bandwidth reported to date. A concept demonstrator using this approach shows contactless RF probing on test structures which show the path towards continuous measurements across the microwave, millimeter-wave and Terahertz range.

In order to meet the requirements of the new generation of radio telescopes, we have developed a new topology called DYQSA, which stands for DYson Quad-Spiral Array. The design exhibits dual circular polarization in contrast to dual linear polarization of state-of-the-art feeds. It covers the required ultra-wideband (UWB) from 2 GHz to 14 GHz with an almost constant and real input impedance which facilitates the design of the feeding structure and the Low Noise Amplifiers (LNAs). Different versions are investigated for enhancing feed performance, ensuring higher aperture efficiencies and mechanical stability. Simulation results of the reflector loaded by the proposed feed show an aperture efficiency of 65±5% can be achieved with a noise antenna temperature around 14 K and a System Equivalent Flux Density (SEFD) of about 1300 Jy, both averaged over the required bandwidth at zenith. Measurements of the single-element and the four-element feeds are presented. Comparisons with other state-of-the-art feeds are shown in terms of total aperture efficiencies, design adaptability to different reflectors, calibration signal injection, the required number of LNAs per feed, cost, and physical volume.

A new sub-terahertz (THz) photomixer with nano-trapezoidal fingers is analyzed, designed, fabricated, and measured. The results are compared with conventional THz photomixers without fingers (or bare gap) and with rectangular fingers. The new design is employed as an emitter as well as a detector and much improved THz power and signal-to-noise ratio (SNR) are obtained. As compared to the antenna with the bare gap and the antenna with rectangular finger tips under the same condition for the optical power and bias voltage, the new photomixer shows seven and two times power enhancement in the emission side, respectively, while in the detection side, it gives a better SNR of 15 and 10 dB, respectively.