Milad Mirzaee

Compact Wideband Microstrip Bandpass Filter Using Quasi-Spiral Loaded Multiple-Mode Resonator

In this letter, a new model for further reducing the size and increasing the bandwidth (BW) of a class of bandpass filter (BPF) utilizing multi-mode resonator is presented. A new technique based on spiral transmission line loading to achieve higher BW and further size reduction is analyzed for this class of BPF. A compact ultra wideband microstrip BPF is proposed by using this technique. The capability of tuning the transmission zeroes in the proposed model is also studied. Estimates for the frequencies of these transmission zeroes are directly presented. The overall BW of the proposed BPF is shown to be increased more than 12.6% and its size to be reduced more than 70% compared with the conventional ones. The proposed BPF provides a relatively wide 3 dB fractional bandwidth of 72.6% frequency response with two transmission zeros at the lower and upper stop-bands to provide a very sharp cutoff and low passband insertion-loss and good return-loss characteristics.

Developing flexible 3D printed antenna using conductive ABS materials

This paper presents the feasibility of conductive acrylonitrile butadiene styrene (ABS) materials in the fabrication of flexible three-dimensional (3D) antennas using additive manufacturing method. To demonstrate this application a bowtie antenna with coplanar waveguide (CPW) feed structure has been designed and measured. The prototype of the antenna has been fabricated using Makerbot® dual 3D printer and flexible polylactic acid (PLA) and ABS filaments for dielectric and conductive parts of the antenna, respectively. To our knowledge, this is the first reported antenna fabricated with conductive ABS material. The dielectric properties of the PLA and ABS filaments have been measured using Agilent performance probe. The fabricated antenna possesses compact size, light-weight and mechanically flexible structure. In addition it achieves wide bandwidth of 24.18 % at the center frequency of 7.81 GHz.

A Novel Small Ultra-Wideband Bandpass Filter Including Narrow Notched Band Utilizing Folded-T-Shaped Stepped Impedance Resonator (Sir)

A compact microstrip ultra-wideband (UWB) bandpass fllter (BPF) including a narrow notched band within the UWB passband is proposed. The proposed fllter is constructed by combination of two highly compact wideband bandpass fllters (BPFs) with difierent physical dimensions which are designed on the basis of a folded-T-shaped stepped impedance resonator (SIR) and parallel- coupling feed structure. The wideband BPFs can be designed separately, and the design procedure is described. The narrow notched band with 3.8% 3dB fractional bandwidth (FBW) from 5.15 to 5.35GHz (IEEE 802.11a lower band) is created in order to eliminate interference from wireless local area network (WLAN) with the determined UWB passband. The center frequency and bandwidth of the notched band can be controlled by tuning the structural parameters. The full-wave EM simulated and measured results are in good agreement, showing that the proposed fllter possesses good characteristics including wide passband, high selectivity, low insertion loss, large notch deep and sharp rejection.

Dielectric property measurement of PLA

3D printing technology provides an affordable method of prototyping antennas. To design antennas with this technology it is necessary to characterize the materials used for printing precisely in terms of their permittivity and conductivity. Two major groups of materials for antenna design are dielectric and conductive materials. In this paper, we consider measurement of dielectric constants of three types of polylactic acid (PLA) plastic materials that can be used for 3D printing of antennas and other radio frequency (RF) devices.

Flexible antenna for Wireless Body Area Network

Wireless Body Area Network (WBAN) systems are the future technology of health monitoring. This paper is focused on the development of a flexible, robust, lightweight, and non-obtrusive antenna in application to a health-monitoring WBAN system for the University of North Dakota (UND) next generation spacesuit 2 (NDX-2). The research on WBAN in space, will both improve future astronauts safety during space exploration, and advance health industry and technologies.

Additive manufacturing of a compact 3D dipole antenna using ABS thermoplastic and high temperature carbon paste

This paper describes a novel method for of three dimensional (3D) printed electromagnetic structures by using additive manufacturing (AM) technology with emphasis on the antenna as an essential component in every wireless communication system. To demonstrate this technique, a dipole antenna has been designed, simulated, and fabricated to work at the center frequency of 3 GHz. The substrate part of the antenna has been fabricated utilizing a desktop 3D printer. Acrylonitrile butadiene styrene (ABS) thermoplastic has been used for the fabrication of the substrate part. A high temperature carbon paste has been utilized to implement the conducting part of the antenna. The measurement results demonstrate that the proposed method can be a good candidate for the additive manufacturing of 3D embedded antennas.

Connector design for 3D printed antennas

Due to a recent growth in 3D printing technology, engineers are able to fabricate affordable and versatile antennas; however, poorly matched antenna terminations continue to limit the capabilities of 3D printed antennas. In this paper a 3D printed bowtie antenna is considered and 3D cable connectors are designed and their performance has simulated. The effect of printer resolution is examined to design the most feasible termination.

A novel design approach to the miniaturization of dual-band branch-line coupler

In this paper, a novel design approach for significant size reduction of a class of dual-band branch-line coupler (BLC) by use of a transmission line model loaded with a folded-T-type stepped-impedance-stub (FTTSIS) is proposed. At the first step, by loading FTTSIS at the middle of each branch instead of stepped-impedance-stub (SIS) in the conventional branch-line coupler, a compact dual-band BLC with same performance that is about 65% of the conventional one is achieved. Then by mirroring the FTTSISs of 35Ω lines inside the inner space of the proposed structure, miniaturized dual-band BLC that is only 30% of the conventional dual-band BLC operating at same WLAN frequencies is obtained. The proposed structure is then fabricated and measured. The measurement results show good agreement with the theoretical ones.

A novel compact UWB BPF with independently controllable double notched bands and super wide upper stopband

This paper presents a novel compact ultra-wideband bandpass filter without and with single or multiple notched bands with significant improvements in size reduction and upper stopband enhancement in comparison with its classical counterparts. A new multiple-mode resonator capable of producing multiple transmission zeros is exploited in the filter structure to produce notch bands and improve performance of the upper stopband. A parallel-coupled structure with tapped-line input/output is applied to significantly improve the selectivity and out-of-band rejection. The proposed filter achieves outstanding electrical performance, with wide passband from 2.93 to 10.64 GHz, two notched bands centered at 5.68 and 8 GHz with rejection level better than 40 dB, low insertion loss, high passband return loss, and wide stopband with suppression level better than −25 dB up to 30 GHz. These attractive features make the proposed filter a viable candidate for any number of broadband wireless communications and radar systems.

A novel compact dual-wideband BPF with multiple transmission zeros and super wide upper stopband

In this article, a novel miniaturised dual-wideband bandpass filter (DWB-BPF) based on two different resonators including a quasi-spiral loaded multiple-mode resonator (QSL-MMR) and L-shaped transmission line (LS-TL) is presented. At the first step, in order to design a single wideband BPF filter with controllable transmission zeros near the centre frequency, the open circuit impedance parameter of quasi-spiral loaded resonator Z21 is determined in terms of ABCD matrix. Then an equivalent circuit model of the proposed structure is derived and the impedance characteristic and electrical length of LS-TLs to achieve a DWB-BPF with excellent selectivity are calculated through even- and odd-mode analysis. The proposed filter possesses both compact and simple structure as well as two wide passbands with fractional bandwidth (FBW) of 70% and 22.8% for its first and second passbands, respectively. The proposed technique creates two transmission zeros at the lower and upper stopbands of each passband resulting in a very sharp roll-off accompanied by a wide stopband. Notably, the circuit size is reduced and the bandwidth is enhanced in comparison with its conventional counterparts. The theoretical performance of the filter is verified by the experimental one where a good agreement is reported between them.