Z. Abolhasani, M. Tayarani,
Volume 5, Issue 4 (12-2009)
Abstract
In this paper, chiral E-shaped resonators are used in a waveguide. Direction of EM wave and position of resonators for effective excitation is studied and various resonances of E-shaped resonators are determined. As a consequence an analytical equivalent circuit model is proposed. Finally, an array of these resonators is used to realize a wide reject band. The resulted band stop filter performance is simulated and a rejection level of almost 40 dB is achieved to confirm the effectiveness of the idea. This stopband filter is used in cascade with a bandpass filter to suppress its spurious response.
M. Khalaj-Amirhosseini, M. Moghavvemi, A. Attaran,
Volume 7, Issue 4 (12-2011)
Abstract
This paper proposes an idea to modify the conventional Wilkinson power dividers to have physically spaced output ports. The well-known internal resistor of Wilkinson power divider is now connected to output ports by two additional transmission lines to create a triangular shape power divider. Several modified power dividers are designed at frequency of 1.0 GHz and one of them is fabricated and measured. The measured results of the fabricated diplexer have very good agreement with the theoretical results.
M. Khalaj Amirhosseini,
Volume 9, Issue 3 (9-2013)
Abstract
In this article, three new green's functions are presented for a narrow strip line (not a thin wire) inside or on a homogeneous dielectric, supposing quasi-TEM dominant mode. These functions have no singularity in contrast to so far presented ones, so that they can be used easily to determine the capacitance matrix of multi-layer and single-layer homogeneous coupled microstrip lines. To obtain the green’s functions, the Laplace’s equation is solved analytically in Fourier integral or Fourier series expressions, taking into account the boundary conditions including the narrow strip. The validity and accuracy of three presented green’s functions are verified by some examples.
D. Zarifi, E. Hosseininejad, A. Abdolali,
Volume 10, Issue 2 (6-2014)
Abstract
A dual-band artificial magnetic material and then a dual-band double-negative metamaterial structure based on symmetric spiral resonators are presented. An approximate analytical model is used for the initial design of the proposed structures. The electromagnetic parameters of the proposed metamaterial structure retrieved using an advanced parameter retrieval method based on the causality principle show its dual-band nature at microwave frequencies.
H. Rahmanian, S. H Sedighy, M. Khalaj Amirhosseini,
Volume 11, Issue 1 (3-2015)
Abstract
A method for design and implementation of a compact via-less Composite
Right/Left-Handed Transmission Line (CRLH TL) is presented. By introducing a new
circuit model, the CRLH transmission line behavior is studied versus the parameters
variations to achieve the desired characteristic impedance and electrical length. Then a
compact quarter wavelength CRLH transmission line with 70 Ω characteristic impedance is
designed as an example. Finally a very compact four way Wilkinson power divider and a
rat-race coupler are designed and fabricated by using this type of CRLH TL which exhibit
about 75% and 80% compactness, respectively.
G. Karimi, F. Sabaghi,
Volume 13, Issue 3 (9-2017)
Abstract
An ultra-wide band band-pass filter using novel spiral stub-loaded triple-mode resonator (SSLTMR) is presented. New spiral stub loaded resonator is analyzed with odd and even modes analysis for this class of BPF, achieving higher band wide and size reduction. In order to have a good response characterized, two (SSL-TMRs) and two quarter wavelength digital coupled lines are used. This new design filter produces triple modes, one odd mode and two even modes in the desired band and two transmission zeroes (TZs) out of band, providing sharp cut off, low insertion-loss and good return-loss characteristics. The measured results are in good agreement with the electromagnetic simulation.
F. Khamin Hamedani, Gh. Karimi,
Volume 14, Issue 4 (12-2018)
Abstract
A novel dual-band bandpass filter (DB-BPF) with controllable parameters in design process and a compact structure is introduced in this paper. The total structure includes open-circuited and short circuited coupled-lines, leading to a compact circuit. The resonance frequencies, insertion loss and quality factor can be independently controlled by adjusting the coupled lines. In order to eliminate the magnetic and electric coupling effects, the virtual grounds are placed in coupled complementary hairpin resonator. To verify the validity of the design approach, a DB-BPF centring, at 3.5 and 5 GHz with respective insertion losses of 0.7 and 0.58dB for WIMAX (IEEE 802.16 band) and WLAN (IEEE 802.11 band) applications has been designed and fabricated, whose the measured results confirm the electromagnetic simulation.
N. Kiani, M. Afsahi,
Volume 15, Issue 2 (6-2019)
Abstract
In this paper, a compact 6.8/7.6 GHz diplexer is provided with the help of substrate integrated waveguide (SIW) structures. The use of this structure is for satellite communication systems. The designed diplexer includes a T-junction. In addition, our structure consists of two SIW filters of the type of bandpass. The relative bandwidth of the upper channel is 3.3% at the center frequency of 7.6 GHz and its lower channel is 3.7% at the center frequency of 6.8 GHz. The proposed diplexer offers a great benefit in terms of size decrease. In addition, it displays an optimal insertion loss. While giving the low return loss. Ultimately, the designed structure displays ideal rates of isolation and rejection. The diplexer incorporates a planar form and can be simply integrated with to the integrated circuits of the microwave. The insertion and return losses are 1.8 dB and 15d B in the lower band and they are 1.9 dB and 17 dB in the upper band. Simulations have been implemented with CST Microwave Studio. The Diplexer is completely built into a standard printed circuit board (PCB) procedure. A very favorable compromise is reached among the results of the construction and the measurement, which is the evidence of the proposed method.
Robab Kazemi, Zohreh Asadollahzadeh-Zia, Reza Masoumi,
Volume 19, Issue 4 (12-2023)
Abstract
In this work, a broadband dual-channel differential phase shifter is developed with a small phase deviation across a wide frequency range. The design consists of two main lines for 45° and 90° phase shifts, along with a reference line. A prototype is fabricated and measured to validate the performance of the design. Phase shifts of 45° ± 5° and 90° ± 5° over a frequency range of 1.26 GHz - 4 GHz (bandwidth of 104%) are achieved from the channels. The transmission losses of the three lines are less than 0.35 dB and the isolation between the adjacent ports is better than 20 dB. The area of this dual-channel differential phase shifter is 
(14.7 mm × 66.15 mm), where 
is the guided wavelength at the center frequency.
