Novel folded SRR-loaded waveguide bandpass filters

A novel class of E-Plane, low-cost, compact and metamaterial-based filter structure using FSRRs for microwave, millimeter wave applications has been proposed. The proposed FSRR-loaded waveguide bandpass filter has been designed and simulated at 9.45 GHz. The structure can be easily realized with a single metal insert within a rectangular waveguide. This kind of filter can be found in applications particularly in the mm-wave range circuits, e.g. in diplexers and multiplexers

Design of generalized Chebyshev lumped element filters by computer optimisation

A numerical method for the optimization of symmetrical lumped element low-pass and band-pass filters with a generalized Chebyshev response is considered. By exploiting the fact that a network based on generalized Chebyshev prototype has a prescribed number of turning points in the insertion loss and an identical number of independent parameters which can be assigned as variables to adjust their levels, the method gives fast convergence

Novel SRR loaded waveguide bandstop filters

Two types of novel split ring resonator (SRR) loaded rectangular waveguide bandstop filter structures have been presented. The first proposed SRR-loaded waveguide bandstop filter has been designed simulated and tested. Using the combination of the split ring resonators, conductive wireline and transversely placed metal septa, the composite material has been built and inserted into the hollow rectangular waveguide to form an SRR-loaded waveguide unit. The bandstop filter has been constructed by cascade of the two resonator unit cells. The second proposed multilayer SRR loaded waveguide bandstop filter has been designed and simulated. Three transverse periodic SRRs are present on either side of the dielectric blocks

A multicarrier amplifier design linearized trough second harmonics and second-order IM feedback

A novel linearisation technique for reduction in the first and second kind of the third-order intermodulation products was applied in this paper. The second harmonics and second-order intermodulation products are led from the output to the input of a power amplifier through a feedback loop. The power amplifier including the feedback loop components (bandpass filter, phase shifter and attenuator) was designed as a hybrid microwave integrated circuit by using program ADS. The phase and amplitude of the loop signals are the adjustable parameters. Therefore, a voltage that controls a phase shift of the phase shifter and a control current of a PIN diode in the attenuator circuit were optimised to obtain a reduction in the third-order intermodulation distortion. For three fundamental signals at the power amplifier input, the lowest improvement of 13 dB for the first and 18 dB for the second kind of the third order intermodulation product levels was achieved

Inkjet Printed Bandpass Filters and Filtennas using Silver Nanoparticle Ink on Flexible Substrate

This paper presents an inkjet printed CPW filtenna designed at 5.8 GHz. The proposed structure consists of a CPW pseudo-interdigital bandpass filter and a CPW inset-fed antenna. The bandpass filter is fabricated using inkjet printing technology. The structure is printed on flexible Kapton substrate with polyimide film using silver nanoparticle ink. The filter is then used to suppress the spurious harmonics of the antenna. Measurements from the fabrication confirm the accuracy of the design method and the simulation results

Hybrid Manufactured Waveguide Resonators and Filters for mm-Wave Applications

Additive and hybrid manufactured waveguide resonators and bandpass filters for mm-wave applications are presented. A Ka band 3D printed waveguide resonator with inductive windows and 28 GHz 5G band hybrid manufactured waveguide resonator and bandpass filter are designed. Hybrid manufacturing combines 3D polymer printing and conventional metal processing technologies. In order to illustrate the accuracy of the design, a 3D printed waveguide transmission line and resonator with the resonant frequency of 33 GHz are fabricated and tested

Ultra Compact Inline E-Plane Waveguide Bandpass Filters Using Cross Coupling

This paper presents novel ultra-compact waveguide bandpass filters that exhibit pseudo elliptic responses with ability to place transmission zeros on both sides of the passband to form sharp roll offs. The filters contain E plane extracted pole sections cascaded with cross-coupled filtering blocks. Compactness is achieved by the use of evanescent mode sections and closer arranged resonators modified to shrink in size. The filters containing non-resonating nodes are designed by means of the generalized coupling coefficients (GCC) extraction procedure for the cross-coupled filtering blocks and extracted pole sections. We illustrate the performance of the proposed structures through the design examples of a third and a fourth order filters with center frequencies of 9.2 GHz and 10 GHz respectively. The sizes of the proposed structures suitable for fabricating using the low cost E plane waveguide technology are 38% smaller than ones of the E plane extracted pole filter of the same order

Low-Cost Hybrid Manufactured Waveguide Bandpass Filters with 3D Printed Insert Dielectric

In this paper, a new type of simple and inexpensive waveguide filter manufacturing that minimizes material consumption and has capabilities of high performance and rapid prototyping is presented. Filter inserts are fabricated by a combination of additive dielectric manufacturing and subtractive metal manufacturing, whereas standard waveguides are used as housings, utilizing best properties of each technology. Along with it, a suitable filter design using metal rectangular rings has been developed. Since the rings that act as positive reactance discontinuities in the passband are resonant at frequencies below it, it is possible to bring lower stopband transmission zeros near the passband to create sharp skirt. A resonator of such a filter and a third order bandpass filter sample have been designed at 11.13 GHz and 11.36 GHz centre frequencies respectively. In addition, smaller size rectangular rings in waveguide can realize upper stopband transmission zeros while acting as negative reactance discontinuities in the passband. This was utilized in fourth order bandpass filter at 11.36 GHz centre frequency with finite transmission zeros in both stopbands. All the filtering structures have been fabricated with 3D printer to extrude polylactic acid and circuit board plotter to mill copper sheet, and tested. Excellent measurement results that have been obtained validate the proposed design. Practical sides of achieving quality 3D printouts are analysed

Linearization of multichannel amplifiers with the injection of second harmonics into the amplifier and predistortion circuit

A linearization technique that uses the injection of the fundamental signal second harmonics together with the fundamental signals at the amplifier input has been extended in this paper by introducing the injection the second harmonics into nonlinear microwave amplifier and so-called predistortion circuit. Predistortion circuit produces the third-order intermodulation signals that are injected at the amplifier input together with the second harmonics making the linearization procedure more independent on the phase variation of the second harmonics. In addition, a considerably better improvement is attained for the power of fundamental signals close to 1-dB compression point by applying the linearization technique proposed in this paper in comparison to the linearization with the injection of the second harmonics merely in the nonlinear amplifier

Experimental Verification of the Impact of the 2nd Order Injected Signals on Doherty Amplifiers Nonlinear Distortion

In this paper, an asymmetrical Doherty amplifier fabricated in microstrip technology is tested in the experiments to verify the impact of the 2nd order signal for the linearization prepared in baseband. The measurement set-up consists of three USRPs programmed by LabVIEW to generate the useful 64QAM signal and the signals for linearization that are set in amplitude and phase and modulate the 2nd harmonic of fundamental carrier. The USRPs instruments should be synchronized for performing measurements for two scenarios: the signals for linearization are injected at input of the transistor within the main Doherty amplifier or are injected at its output