Analysis and Design of a Substrate Integrated Waveguide Multi-Coupled Resonator Diplexer

A microwave diplexer achieved by coupling a section of a dual-band bandpass filter onto a section of two single-bands (i.e. transmit and receive) bandpass filters is presented. This design eliminates the need for employing external non-resonant junctions in diplexer design, as opposed to the conventional design approach which requires separate non-resonant junctions for energy distribution. The use of separate non-resonant junctions in diplexer design increases the design complexity, as well as gives rise to bulky diplexer devices. The proposed design also removes the too much reliance on the evaluation of suitable characteristic polynomials to achieve a diplexer. Though the evaluation of complex polynomials to achieve a diplexer is seen as a viable option, the technique is hugely dependent on optimisations which come with loads of uncertainties. This thesis relies on well-established design formulations to increase design reliability, as well as simplicity. A 10-pole (10ᵗʰ order) microwave diplexer circuit has been successfully designed, simulated, manufactured and measured. The measured results have been used to validate the circuit model and the electromagnetic (EM) simulated results. The diplexer is composed of 2 poles from a dual-band bandpass filter, 4 poles from a transmit bandpass filter and the remaining 4 poles from a receive bandpass filter. The design was initially implemented using asynchronously tuned microstrip square open-loop resonators. The EM simulation and the measurement results of the microstrip diplexer were presented and show good agreement with the proposed design theory. The design was also implemented using the substrate integrated waveguide (SIW) technique and results presented and discussed. In comparison to the results achieved with the microstrip diplexer, the EM simulation and the measurement results realised with the SIW diplexer, show that a slightly better insertion loss was attained across both the transmit and the receive channels, respectively

Microwave diplexer purely based on direct synchronous and asynchronous coupling

A diplexer realized purely based on direct coupling is presented. No cross-coupling is involved in the design process. The microwave diplexer is achieved by coupling a dual-band bandpass filter onto two individual channel filters. This design eliminates the need for employing external junctions in diplexer design, as opposed to the conventional design approach which requires separate junctions for energy distribution. A 10-pole (10th order) diplexer has been successfully designed, simulated, fabricated and measured. The diplexer is composed of 2 poles from the dual-band filter, 4 poles from the Tx bandpass filter, and the remaining 4 poles from the Rx bandpass filter. The design was implemented using synchronously and asynchronously tuned microstrip square open-loop resonators. The simulation and measurement results show that an isolation of 50 dB is achieved between the diplexer Tx and Rx bands. The minimum insertion loss is 2.88 dB for the transmit band, and 2.95 dB for the receive band

U-Shaped terahertz microstrip patch antenna for 6G future communications

In this article a terahertz antenna has been proposed which is designed on Rogers RO3010 substrate, with a standard thickness 10 µm having relative dielectric constant (Ɛr) = 11.2 and thermal conductivity of 0.66 W/K/m. A dielectric material with a high epsilon value is used, the effective wavelength of the electromagnetic wave is reduced within the material, resulting in a reduction of the physical size of the antenna. The designed antenna is compact light weight and is fed using a microstrip line feeding technique which provides ease of integration inside the device. The resonating frequency of the designed antenna is 0.854 THz with a return loss -19.5 dB offering a high bandwidth of 44 GHz. High bandwidth application of the future communication requirements is achieved by the modelled antenna

Sub-terahertz microstrip antenna array for future communication

In this article, a microstrip patch antenna array has been designed for sub-terahertz application. The designed antenna array consists of four rectangular-shaped radiating patches which are fed using the microstrip line feeding technique. The dielectric material utilized as a substrate is Roger RO3010 which has an epsilon value of 11.2, responsible for compact antenna size, it also exhibits minimal energy absorption and dissipation. The designed antenna has achieved acceptable simulated results of important parameters which include radiation pattern, Gain, and return loss, Bandwidth, current distribution, and impedance matching of the antenna. The designed antenna array offers increased bandwidth, enabling higher data rates and ultra-low latency. The proposed Sub-terahertz antenna array can support the deployment of high-speed, low-latency wireless networks for applications such as virtual reality (VR), augmented reality (AR), autonomous vehicles, and smart cities

Coaxial feed ultra-wideband microstrip antenna for medical applications

In this article, an ultra-wideband antenna has been presented for medical applications which have a resonant frequency of 10.35GHz and offers a bandwidth of 1400MHz with a return loss of -19db. The presented antenna is low-cost lightweight and can easily be integrated inside the circuit. As this antenna is designed for medical applications its size is compact and is fed utilizing a coaxial feeding technique which is especially plentiful for operative radiotherapy applications. The designed antenna is rectangular and covers an overall size of 24x12mm with a thickness of 1mm. The proposed antenna is designed using CST studio as a simulation tool, the extracted results of important parameters like return loss, surface current, reference impedance, and far-field have achieved remarkable results which are illustrated in the article. which makes it suitable for radiotherapy. A high epsilon valued εr = 4.8, tan δ = 0.02 substrate GT-008 has been employed as a dielectric material whereas copper is being used for the ground and radiating patches. The performance of the antenna in the X-band is satisfactory which makes it suitable for radiotherapy

Symmetric 3dB filtering power divider with equal output power ratio for communication systems

This paper presents a two-way filtering power divider (FPD) with an equal output power ratio of 1:1. This implies that each of the FPD output port would receive 50% of the power at the input port. To achieve miniaturisation, a common square open-loop resonator is used to distribute energy between the two integrated Chebyshev bandpass filters. In addition to distributing energy, the common resonator also contributes one pole to each integrated bandpass filter (BPF), hence, reducing the number of individual resonating elements used in achieving the integrated FPD. To demonstrate the proposed design technique, a prototype FPD centred at 2.6 GHz with a 3 dB fractional bandwidth of 3% is designed, simulated and presented. The circuit model and microstrip layout results of the FPD show good agreement. The microstrip layout simulation responses show that a less than 1.1dB insertion loss and a greater than 16.5dB in-band return loss were achieved. The overall footprint of the integrated FPD is 37mm by 13mm (i.e. 0.32λg x 0.11λg, for λg = guided-wavelength of the 50Ω microstrip line at 2.6 GHz). The integrated FPD reported in this paper shows some promising merits when compared to similar devices recently reported in literature

Substrate integrated waveguide (SIW) bandpass filter with novel microstrip-CPW-SIW input coupling

A Substrate integrated waveguide bandpass filter is presented with a novel CPW-to-SIW transition at both the input and output ports which also served as the input and output couplings into the filter. The CPW-to-SIW transition structures presented here exploited the step impedance between the 50 ohms input/output feedline and the transition to control the input/output couplings of the filter. The SIW filter is also shown to have very minimum milling or etching requirement which reduces the fabrication error. The proposed SIW filter has been validated experimentally and results presented. The results show that a simulated return loss of 15 dB and an initial measured return loss of 16 dB were achieved. An improved measured return loss of 22 dB was later achieved after some tuining adjustments were performed on the filter input and output couplings. A minimum insertion loss of 1.3 dB was also achieved across the band