Waveguide Diplexer Research Articles

Substrate-integrated waveguide diplexers with improved Y-junctions

Y-junctions are often adopted to design diplexers since their characteristics can conveniently satisfy the constraints for optimum performance of diplexer design. In order to decrease the size of the Y-junction diplexer, the two branches of the junction can be bent to yield parallel outputs. However, this parallel configuration can degrade the characteristic of the Y-junction. In this letter, two improved novel configurations of Y-junction diplexers are introduced, analyzed with an efficient mode-matching based approach and optimized for best performance. For illustration, the method is applied to two diplexers in substrate-integrated waveguide technology realized using band-pass post filters. For each diplexer, the fractional bandwidths of operation for the up and down channels are 2.70% and 2.44% at 7.4 GHz and 8.2 GHz respectively. The viability of the design approach is validated by full-wave finite-element simulations using Ansys HFSS and measurements on the two fabricated diplexers. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1384–1388, 2016

A Millimeter Wave High-Isolation Diplexer Using Selectivity-Improved Dual-Mode Filters

This letter presents an alternative method to realize millimeter wave waveguide diplexers based on high selectivity bandpass filters. A small perturbation is implemented in a dual-mode circular cavity to expand the bandwidth and significantly enhance the selectivity of the channel filter. The location of a transmission zero can be easily adjusted by properly changing the angle of a perturbing notch etched at sidewall of the cavity. A V-band diplexer prototype has been fabricated and tested. The experiment results showed good agreement with simulation results. The designed diplexer has the advantages of simple design process, quasi-planar structure, high isolation, and improved selectivity without any additional mechanical tuning element.

Substrate Integrated Waveguide Diplexer Based on Circular Triplet Combline Filters

The design of substrate integrated waveguide (SIW) diplexers, based on combline triplet sections with transmission zeros (TZs) placed below and above the passband, is presented. In order to control the location of the TZs, positive and negative couplings are conveniently provided. A highly compact implementation based on circular substrate integrated coaxial resonators is proposed. An X-band diplexer with channel center frequencies at 9.5 and 10.5 GHz and absolute bandwidths of 400 MHz is designed. The structure shows important advantages in terms of size reduction, while keeping good insertion losses as well as high rejection and isolation levels.

Design of millimetre wave diplexers with relaxed fabrication tolerances

A novel millimetre wave waveguide diplexer topology that can be fabricated using relaxed fabrication tolerances is presented. This is achieved by using a highpass filter/hybrid coupler topology in addition to a low order capacitive iris bandpass filter. By targeting the most sensitive centre resonators in the bandpass filter and increasing their length to full wavelength, the sensitivity to fabrication errors associated with changes to the resonator length can be reduced without the introduction of spurious responses close to the passband. The main benefit of this topology is that only one bandpass filter is required to realise the final diplexing response. This is advantageous when tolerance is considered as it is found that resonating structures associated with bandpass filters contribute to tolerance effects. In addition to this, the authors find that the choice of iris discontinuity used to realise the impedance inverters in the bandpass filter can help to relax fabrication tolerances. By subjecting the proposed circuit to a tolerance analysis, simulated results suggest that the circuit can be fabricated with relaxed fabrication tolerances. These discussions are verified with the fabrication of a Ka-band waveguide diplexer, where the measured and simulated scattering parameters are in very good agreement.

E-band cavity diplexer based on micromachined technology

A robust and tuneless micromachined waveguide diplexer operating in the frequency range 71–86 GHz is here presented. The diplexer is based on multiple coupled cavities and it is manufactured using micromachining technology on two staked silicon layers. The diplexer consists of two filters combined to a common waveguide port via an E-plane T-junction. The two eight-order band-pass filters are centered at 73.5 and 83.5 GHz. The fractional bandwidths for two bands are 8.8 and 7.8% at higher- and lower-band, respectively. The measured insertion loss is below 0.7 dB for both the filters and the diplexer isolation is better than 55 dB, as required. The proposed technology allows for a very compact device (<20 × 20 × 1.5 mm) and the first prototypes were proved to be very robust to manufacturing tolerances and environmental tests, thus leading to an excellent tuneless manufacturing yield in future production. The diplexer will be employed in next generation terrestrial radio-link communications front-ends.

Research and Development of 2-frequency (110/138 GHz) FADIS for JT-60SA ECHCD system

A FAst DIrectional Switch (FADIS) of 2-frequency (2-ƒ ) gyrotron system for the JT-60SA project is being developed under collaboration between Japan Atomic Energy Agency (JAEA) and Kyushu University. At first, the frequency drift and dip in the gyrotron operation were measured to consider which kind of FADIS is preferred for application in the Electron Cyclotron Heating and Current Drive (ECHCD) system for the JT- 60SA. Various types of the FADIS have been considered. A square corrugated waveguide diplexer system with double resonant rings was considered as one of the most attractive FADIS systems for stable high-power and long-pulse operations in the 2-ƒ JT-60SA ECHCD system.

Combining gigawatt level X-band high power microwave beams with an overmoded circular waveguide diplexer

The high power microwave (HPM) beam combining results at X-band with an overmoded waveguide diplexer are presented. As the key device for the beam combining experiments, the diplexer is designed, fabricated, and tested. Then the beam combining experiments under short and long pulses are performed at HPM source, respectively. The experiment results reveal that short and long pulse HPM beams have been successfully operated without microwave breakdown at 3-GW with pulse duration of 25 ns and 1.3-GW with pulse duration of 96 ns. According to the experiments, conservative breakdown thresholds for the diplexer are concluded to be 800 kV/cm and 550 kV/cm, respectively, under the short and long pulse HPM conditions.

High-yield E-band diplexer for fixed radio point-to-point equipment

The article describes practical guidelines for an E-Band tuning-less waveguide diplexer design 71-86 GHz which requires looser fabrication tolerances and provides higher yield than traditional methods. Physical considerations concerning sensitivity to manufacturing inaccuracies are discussed and proven by designing and manufacturing two different diplexers on a set of typical specifications. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:508-512, 2014.

Design of Single-Branch Laminated Waveguide Diplexers Using Modal Orthogonality

This paper develops novel laminated waveguide diplexers by taking advantage of the modal orthogonality of multiple cavity modes. The uplink and downlink channels of the diplexer can share a common filter structure, which minimizes the number of the cavities. The feeding probes and coupling slots are adequately located to achieve the required coupling coefficients and external quality factors at both passbands simultaneously. In this way, the matching network, i.e., T-junction, adopted in the traditional diplexer design can be eliminated. In addition, by the symmetric but orthogonal field distributions of two operation modes, nearly 30 dB of isolation can be achieved even by sharing the common cavities. The cavities are vertically stacked in low-temperature cofired ceramic technology, which further miniaturizes the circuit size. Two diplexers with third-order Chebyshev responses are designed and fabricated with different operation modes to show the flexibility in the band allocation. Experimental and simulated results are presented, both validating the design concept of the proposed diplexers.

Compact Diplexer With High Isolation Using the Dual-Mode Substrate Integrated Waveguide Resonator

This letter presents a substrate integrated waveguide (SIW) diplexer using the dual-mode resonator. By enhancing the perturbation strength, the resonant frequencies of the dual-mode square cavity can be assigned to required frequencies. Thus, the cavity can be employed as the common resonator to replace the T-junction. The coupling aperture between the common resonator and the triangular resonator is parallel to one resonant mode's magnetic field and perpendicular to the other's. As a result, the isolation between the two channels is increased. Furthermore, the cavities are vertically stacked to realize a compact size. A diplexer with lower and upper channels centered at 8 and 9 GHz, respectively, is designed to verify the proposed concept. The simulated and measured results agree with each other.

Modelling of dual‐polarisation diplexers based on enhanced multiport turnstile junctions

The modelling of waveguide diplexers working simultaneously with two dual-polarisation signals is presented in this study. The proposed network is an ortho-mode junction with six physical ports based on an enhanced multiport turnstile junction. This structure is excited at the common port coming from the antenna, by two signals at different frequency bands which are required to be discriminated into dedicated ports. The added functionality of the structure presented in this work is that each frequency band can also allocate two orthogonal polarisations (dual linear or dual circular) with a very large separation between bands (fractional bandwidth larger than 55%), using two different waveguiding concepts. The first one is based on confining the high frequencies at the centre of the axial path. The second one is just the dual, diverting the high frequencies to the outer boundaries of the axial path. The proposed structures, whose modelling and design will be addressed, are suited for low insertion loss and high-power applications, since they do not use metallic pins, irises or small waveguide sections. Moreover, as consequence of the introduced waveguiding concepts, they are very compact and short in the axial direction, which is crucial for this type of feeders in satellite applications.

자계면 T-접합 구조를 갖는 X/Ku 밴드 도파관 다이플렉서의 설계

In this paper, X/Ku band waveguide diplexers with H-plane T-junction for satellite communication systems is proposed and its characteristics is cinfirmed. Two frequency bands such as X(7.25 ~ 8.4 GHz) and Ku(12.25 ~ 14.5 GHz) can be separated by the proposed waveguide diplexers. A diplexers is normally including low pass filter, high pass filter and junction waveguide. To simplify the structure of the proposed diplexers, the proposed waveguide diplexers is using impedance matching technique on H-plane of the high pass filter without low pass filter. To use vertical and horizontal polarization, the proposed diplexers with orthomode transducer(OMT) characteristics is also designed. Therefore, it is confirmed that the proposed waveguide diplexers can be used as dual-band and dual-polarization diplexers for satellite communication feed systems.

Design of a Waveguide Diplexer Based on Connected Bi-Omega Particles

In this letter, we propose a new waveguide diplexer based on the employment of connected bi-omega particles. The component consists in a junction between three waveguides with the same cross-section. At either of the junction sections between the feeding waveguide and the two output ones, we place a set of connected bi-omega particles. The two sets of particles have different dimensions, in order to resonate at two different frequencies, enabling, thus, the frequency selective transmission required for the diplexer operation. The design is supported by proper full-wave numerical simulations and measurements.

COMPUTER-AIDED DESIGN OF Y-JUNCTION WAVEGUIDE DIPLEXERS

Waveguide diplexer designs are widely used for telecom- munications, space, and terrestrial applications. Although mathemat- ical models and design procedures for waveguide fllters are known, diplexer designs still remain complex and time consuming. This pa- per describes how to obtain an equivalent circuit network model and a complete design of non-contiguous diplexers using a computer-aided approach with a classic Y-junction. Results are satisfactory in terms of reduced design time and performance. Examples including physical dimensions are provided.

Implementation of rigorous EM simulations for design and production of narrow band waveguide diplexer

AbstractIn this article the advanced modeling and simulation of narrow band waveguide diplexer for radio‐relay links at 13 GHz is presented. Three different electromagnetic simulation packages were used for design of diplexer with 0.76% of fractional bandwidth and 2% of channel spacing. Simulation tools are compared concerning their accuracy in the prediction of central frequency, bandwidth, insertion and return losses and out of band attenuation. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1032–1036, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23277

Novel Approach to the Synthesis of Microwave Diplexers

A procedure for synthesizing microwave diplexers is presented. It is based on the evaluation of the characteristic polynomials of the diplexer including the three-port junction connecting the TX and RX filters (two types of junctions are considered, suitable for waveguide and coaxial diplexers modeling). The novel method is particularly suited for small separation between the two diplexer channels: as known, this is the most difficult case in the diplexers design, due to the strong interaction between the TX and RX filters. The proposed synthesis approach offers noticeable design flexibility, as it allows the synthesis of the two composing filters independently of their connections to the diplexer, taking into account at the same time the interaction produced in the diplexer junction. Moreover the choice of the filters topology is absolutely arbitrary (the number of poles and the transmission zeros of the two filters have to be specified). The proposed method has been validated by the design and fabrication of a diplexer for global system for mobile communications base stations

Tunable T-Shaped Waveguide in Two Dimensional Photonic Crystals Based on Liquid Crystals

In the last years, in order to achieve active tuning of photonic crystals devices, the possibility to use liquid crystal inside photonic crystals has been explored. On this line of argument, in this paper, we numerically investigate a tunable T-shaped waveguide diplexer, based on a two-dimensional square lattice photonic crystal composed of silicon rods in a liquid crystals. We prove that complete splitting of the entire input wavelengths range in two sub-ranges symmetrical with respect to the middle (switching) wavelength, and propagating in right and left arms respectively, can be achieved. Moreover, changing the refractive index of liquid crystals by electro-optical effect, a tuning of switching wavelength of about 60 nm can be obtained.

Active Photonic Crystals Based multiplexer

ABSTRACTIn the last years, in order to achieve active tuning of photonic crystals devices, the possibility to use liquid crystal inside photonic crystals has been explored.On this line of argument, in this paper, we numerically investigate a tunable T-shaped waveguide diplexer, based on a two-dimensional square lattice photonic crystal composed of silicon rods in a liquid crystals. We prove that complete splitting of the entire input wavelengths range in two sub-ranges symmetrical with respect to the middle (switching) wavelength, and propagating in right and left arms respectively, can be achieved. Moreover, changing the refractive index of liquid crystals by electro-optical effect, a tuning of switching wavelength of about 60 nm can be obtained.

Substrate integrated waveguide (SIW) asymmetric dual-mode filter and diplexer

Substrate integrated waveguide (SIW) can be used to implement high Q waveguide components with the same easy and low-cost fabrication process as planar circuits. In this paper two inline three-pole dual-mode filters with asymmetric transmission response based on SIW are presented. These two filters, consisting of a TE102-TE301 dual-mode SIW cavity and a TE101 mode SIW cavity, are centred at around 10 GHz with a transmission zero on the left of the passband and the right of the passband, respectively. Based on the two kinds of three-pole deal-mode filters, a diplexer with isolation better than 35 dB is developed. A linear microstrip taper is used to implement the transition between microstrip and SIW. The measured results agree with simulated results.

Dimensional Synthesis for Wide-Band Waveguide Filters and Diplexers

Broad-band waveguide filter and diplexer designs are widely used for telecommunications, space, and terrestrial applications. Fairly accurate design procedures giving equivalent-circuit information are well known for bandpass filters, but this data needs to be converted into physical dimensions, i.e., waveguide cavity lengths and iris dimensions. A novel procedure giving dimensions of bandpass filters directly for wide- and narrow-band applications is described. Iris network models are generated with the aid of electromagnetic simulators and used to derive correct iris dimensions and accurate susceptance slope parameters of the cavities, avoiding global optimization of the entire structure. The results demonstrate very good equiripple performance up to bandwidths of approximately 20% in frequency or 40% in terms of guide wavelength. A similar dimensional synthesis to design waveguide noncontiguous bandpass diplexers is also given. The method uses a fast and efficient optimization with a reduced number of variables, which is fixed and independent of the order of the two filters. The simplicity of the method leads to good return-loss levels and the derivation of the diplexer dimensions takes less than 10 min, including optimization.