In this paper a C-band, low phase noise voltage controlled oscillator is presented based on Substrate Integrated Waveguide (SIW) resonator. As the SIW resonator plays a great role on the noise performance of the voltage controlled oscillator, the effects of some parameters on the performance of the SIW are investigated. Considering various techniques of excitation and tuning, an SIW resonator is designed in the frequency range of 5 to 6.3 GHz. The resulting tunable resonator has a quality factor of 240 at 5.5 GHz, when simulated on RO4003 Substrate. The voltage controlled oscillator can oscillate from 5.3 GHz up to 6.3 GHz. The tuning voltage for this frequency range is between 2 and 20 Volts. The oscillator phase noise is better than -112dBc/Hz at 100 KHz offset from the 5.5 GHz carrier.

A compact, wideband, low cost, high radiation efficiency and planar half mode Substrate Integrated Waveguide (HMSIW) horn antenna is proposed in this work. For the first time, HMSIW is used to design a horn antenna. By using HMSIW Waveguide structure instead of Substrate Integrated Waveguide (SIW), the impedance bandwidth of antenna is increased significantly. The use of this Waveguide structure in the design of the horn and its feeding system has increased the impedance bandwidth of the antenna. In fact, leaking the electromagnetic waves gradually along the horn increases the bandwidth of antenna. By applying the design equations of the H-plane horn antenna and half mode Substrate Integrated Waveguide, the initial dimensions of the antenna have been obtained, then the best possible solution has been extracted by parametric study and optimization. Simulation results exhibit an impedance bandwidth of 50% from 24GHz to 40GHz. Also, the proposed design shows a gain between 7dB and 10 dB together with radiation efficiency higher than 95% over the frequency band of 25 to 35GHz. The innovation of this work is in providing a new horn structure based on HMSIW with wide impedance bandwidth. In the previously presented works, which are mainly based on SIW, the antenna suffers from a narrow impedance bandwidth.

A new wideband Wilkinson Power Divider which use the nonuniform Substrate Integrated Waveguide (NSIW) method is presented in this paper. This structure utilizes NSIWs instead of the uniform quarter wavelength SIWs in conventional Wilkinson power divider. The proposed structure is analyzed by odd and even mode analysis. The proper NSIW section widths can be extracted by using even mode while the divider resistances are achieved by odd mode analysis. Moreover using of half mode structure in the NSIW and two output ports reduces the overall size of the proposed divider. Finally a wideband Wilkinson power divider is designed and simulated to verify the proposed design method. A good return loss (S11, S22) and insertion loss (S21) across a very wideband width from 10 GHz to 20 GHz is achieved. Also, the isolation (S23) is better than -10 dB from 9.5 GHz to 21.5 GHz for the designed NSIW divider.

In this paper a miniaturized diplexer for WLAN and WiMAX applications is presented, based on half-mode Substrate Integrated Waveguide (HMSIW) technology by loading a novel metamaterial unit-cell. The proposed metamaterial unit-cells are called fractal open complementary split-ring resonators (FCSRRs). The proposed FCSRRs behave as electric dipoles if appropriately stimulated, and are able to generate a forward-wave passband region below the cutoff frequency of the Waveguide structure. The electrical size of the proposed FCSRRs unit-cell is smaller than the conventional CSRRs unit-cell. Therefore, the FCSRR unit-cell is a good candidate to miniaturize the SIW structure. The proposed diplexer has been designed by cascading two bandpass filters with different center frequencies. The HMSIW bandpass filters are implemented by etching two FCSRR unit-cells with different sizes. The design procedure is based on the theory of evanescent mode propagation in which the FCSRR unit-cells behave as electric dipoles. A forward-wave passband below the intrinsic cutoff frequency of the HMSIW structure has been achieved by loading the FCSRR unit-cells on the metal surface of the HMSIW structure. This proposed diplexer displays high selectivity and compact size by using sub-wavelength resonators. The designed diplexer has been fabricated and experimental verifications have been provided. The measured results are in a good agreement with the simulated ones. The total size of the proposed diplexer is about 0. 30 λ g × 0. 09 λ g. The proposed diplexer shows significant advantages in terms of size reduction, low loss, high selectivity, high Q-factor, easy bandpass frequency shifting, easy fabrication and easy integration with other planar microwave circuits.

In the modern era, the antennas with cosecant squared pattern play a significant role in radar applications. These applications are used to cover an airspace to search for targets and estimate their height. In this article, a method is proposed for the synthesis of cosecant squared pattern using leaky wave antenna. The principal mechanism in the leaky wave antennae is wave attenuation due to power leakage while the wave propagates through the structure. Thus, by controlling the leakage and phase constants along the length of the structure, one can synthesize the desired radiation patterns. We have used the genetic algorithm to optimize the leakage constant and obtain the desired cosecant squared pattern In the range of 10 to 30 degrees. Conformity in simulation results and measured results indicates accuracy in the design process. The proposed method obtains the desired pattern with a ripple of less than 2 dB in the designated area and side lobe level less than-18 dB, which makes the antenna suitable for radar applications.

This paper presents a filtering power divider (PD) /power combiner (PC) using Substrate Integrated Waveguide (SIW) -based 180o hybrid. The utilized 180o hybrid includes a standard H-plane 3-dB coupler and a broadband 90o phase shifter. The phase shifter is composed of non-radiating longitudinal slots patterned on the top conducting surface of the SIW. We have added the filtering property to the structure by an array of dissimilar transverse slots. The slots dimensions are obtained by the extracted external quality factor, coupling coefficient and the relationship between them and the slots dimensions. The proposed structure is designed for 8.2 GHz and investigated by ADS simulator. The results show the fractional bandwidth of the sum and difference ports are 13.7% and 14.93%, respectively. For sum operation, the minimum insertion loss is 3.78 dB and the return loss is above 25 dB in the passband. For difference operation, the minimum insertion loss is 3.81 dB and the return loss is above 26 dB in the passband.

In this pare, a wideband three-order bandpass filter (BPF) is proposed. The proposed wideband filter is designed using the Substrate Integrated Waveguide (SIW) structure by loading T-shape slots. A BPF with two resonators is formed by etching T-shape slots with different size on the top metal plane of the SIW structure. The proposed filter is investigated with the theory of coupled resonator circuits. The T-shape slots which etched on the SIW structure are used to form up a new multiple-mode resonator (MMR) in order to achieve a wide passband of operation while keeping the overall size of the proposed filter to be much compact. The design procedure as well as design curves of the filter are given and discussed here. Compared with some other reported BPFs with SIW technique, the presented BPF using the SIW structure loaded by T-shape slot has great improvements on size reduction and selectivity. In order to prove the validity, the proposed wideband SIW BPF on a single layer printed circuit board (PCB) is designed and experimentally examined. The measured results show that the filter achieves an insertion loss of 1. 1 dB at 6. 4 GHz and a return loss of higher than 22 dB. The proposed filter has a pass-band covers 5. 1 to 7. 99 GHz and its simulated and measured 3 dB fractional bandwidth is about 44. 3%. The measured results are in a good agreement with the simulated results.

A four-way power divider/power combiner using Substrate Integrated Waveguide (SIW) and microstrip lines is proposed and investigated. The proposed power divider consists of a double-layer Substrate with a bottom layer including an SIW T-junction and a top layer including a microstrip network. This microstrip network consists of a modified Gysel power divider which provides a high isolation between output ports by using two grounded resistors. Meanwhile, this modified Gysel power divider maintains high power-handling advantage over Wilkinson power divider. A transition between the SIW T-junction and microstrip network is realized by etching two rectangular slots on the middle metal layer. The even-odd mode method is used to analyze the presented structure. A prototype of the proposed power divider is designed, simulated, and fabricated. The results show that the return loss of the input port is better than 12 dB over 8. 43 to 10. 57GHz. Also, the output return losses and isolation are better than 10. 5 dB over the whole bandwidth.

In this paper, a new single layer half mode Substrate Integrated Waveguide (HMSIW) magic-T utilizing H-plane HMSIW power divider and E-plane slotline-to-HMSIW transition has been designed and proposed. By using slotline in the E-plane T-junction, a 180° out-of-phase between two output ports has been generated. In order to optimize return loss and split the input signal equally into two in-phase signals at the output ports, a metallic via hole in the H-plane T-junction has been used. The magic-T is simulated and optimized by Ansoft HFSS software and a Ku-band prototype is designed and fabricated using the standard printed circuit board process. Experimental results demonstrate that the return losses are less than 10 dB, and the fabricated HMSIW magic-T has a 17% bandwidth over frequency range of 12. 8-15. 2 GHz with 0. 34 amplitude imbalances and 3° phase differences in the output ports.

circularly-polarized antenna is built based on new SIW(Substrate Integrated Waveguide) structure which contains cavity-backed resonator and a conventional polarized ring with two square slits in inner and outer ring that differ 90° at position and is proposed for right-handed circular polarization (RHCP) and fabricated in two separate layers. A broadband impedance bandwidth of 13.9% and a RHCP axial ratio of 0.5GHz have been obtained under the condition of less than VSWR ≤2 and axial ratio≤ 3 dB, respectively.