Terahertz astronomy has been exceptionally unexplored until the last decades due to a technological gap, but exactly at these wavelengths the most distant galaxies appear very bright. Efficient instruments that are capable of spectrometry are essential in understanding the physics of these distant objects. Within the framework of this thesis, an efficient, moderate spectral resolution, on-chip filterbank spectrometer is presented. Several band-pass filter units were investigated and compared, being the directional band-pass filter the most robust and performing. A circuit model is constructed for each of these units and arrayed into a filterbank configuration resorting to microwave techniques. The performance of the filterbank with the circuit model, both with and without realistic losses and tolerances is modeled. A microstrip directional band-pass filter unit has been designed and arrayed into a filterbank chip design. A test filterbank chip based on this design has been fabricated. Due to fabrication issues the detector yield was too poor to allow in-depth and statistically significant measurements. Despite this, the filterbank design is expected to outperform state-of-the-art superconducting filterbanks in terms of coupling efficiency.

Superconducting detectors such as Microwave Kinetic Inductance Detectors (MKIDs) have lead to the designs of THz on-chip spectrometers such as DESHIMA. With DESHIMA a wideband THz signal is fully sampled by several hundreds of channels of which the frequency is defined by an array of band-pass filters. Each band-pass filter which is connected to a separate MKID which can be read-out simultaneously by a microwave read-out signal. This single-pixel system can be expanded through the implementation of steerable antennas. Especially when several spectrometers are used to create a multi-pixel spectrometer, the process of measuring the Universe's background radiation could be sped up and also be used to calibrate the instrument. In this thesis an on-chip platform is designed which is able to quantify the achievable phase-shifting capabilities of a superconducting microstrip line at terahertz frequencies. This is done by exploiting the non-linear behavior of a superconductor's kinetic inductance to a dc current. DC-biased superconducting Fabry-Pérot (FP) resonators, replacing the role of the filter-bank mentioned above, have been investigated and designed to quantify the phase-shifting capabilities by probing the shift in the resonance frequency. The injection/extraction of DC biasing currents on the FP resonator need to be transparent to the THz frequencies. To do so, low-pass stepped-impedance filters have been designed. A Chebyshev filter has been implemented with a stepped-impedance filter which has a minimal rejection of 45 dB between 300 and 400 GHz. This is necessary to prevent leakage of the THz signal into the bias feeds. The two filters reactively load the FP and have an effect on the Q-factors. This change, without any bias current applied, is small enough to be neglected. The tuning of the FP with a dc bias current is limited by the critical current the superconductor can support. This is determined by the geometry and material characteristics of the superconductor. The sensitivity of the superconductor to a dc current is limited by its kinetic sheet inductance. The larger this value is, the larger the tuning range. The results of the simulations shown that with this design it is possible to obtain a phase shift of roughly 0.7% which coincides with phase shift values found in other studies. It is therefore possible to implement this design to create beam-steerable superconducting antennas. The design is being fabricated as this is written and will be measured in the coming months.