Xiaoyu Cheng

A Compact Omnidirectional Self-Packaged Patch Antenna With Complementary Split-Ring Resonator Loading for Wireless Endoscope Applications

A patch loaded with a complementary split-ring resonator (CSRR) is fabricated on a flexible substrate and folded in a cylindrical shape, forming a self-packaged folded patch antenna with a quasi-omnidirectional radiation pattern. The space inside the cylindrical cavity is electromagnetically shielded by the ground plane of the patch, and therefore electronic circuits can be accommodated in it with little electromagnetic interference (EMI) from the antenna or other external electronics. The CSRR contributes to size reduction. As a test vehicle, a 2.4-GHz ISM-band folded patch antenna is designed, fabricated, and characterized for a wireless capsule endoscope application, where the implemented antenna has a patch length of 10.5 mm (0.11λ ) and a folded cylinder diameter of 10 mm. A 74% size reduction is achieved after CSRR loading. The antenna located at the outermost surface not only functions as an electromagnetic radiator and an EMI shield, but also serve as a mechanical packaging structure.

Electrically Tunable Evanescent Mode Half-Mode Substrate-Integrated-Waveguide Resonators

Electrically tunable evanescent mode half mode substrate integrated waveguide (HMSIW) resonators are implemented for S band applications. An HMSIW loaded with a complementary split ring resonator (CSRR) achieves forward electromagnetic wave transmission below the characteristic waveguide cutoff frequency due to evanescent wave amplification. A variable capacitor connected to one of the conductors of the CSRR changes its effective capacitance to ground, resulting in frequency tuning of the resonator. Three different configurations are investigated with a varactor diode connected between the ground and three different contact points of the CSRR. The external Q factor is slightly affected by the frequency tuning. More than 15% tunability is achieved around 3.4 GHz. Full wave structure simulation results are in good agreement with those of measurement.

Single and dual band bandpass filters using complementary split ring resonator loaded half mode substrate integrated waveguide

High performance microwave bandpass filters with low insertion loss, high selectivity, compact size and multiple bands are widely used for wireless and satellite communication systems [1]. During the years, bandpass waveguide filters have used all kinds of metallic and non-metallic insertions in order to improve performance and reduce size [2]. Since the first experimental demonstrations of metamaterial particles exhibiting either negative permeability such as the split ring resonators (SRR), or negative permittivity such as the complementary split ring resonators (CSRR), different implementations combining waveguide with such structures have been widely investigated for bandpass filters [3–4], mainly motivated by their extraordinary property of generating backward wave transmission below the waveguide cutoff frequency. On the other hand, the need for new applications and integration with digital circuitry is the motivation for proposing and implementing planar microwave filters with performances similar to those provided by the bulky waveguide filters. The substrate integrated waveguide (SIW) and the half mode substrate integrated waveguide (HMSIW) [5–6] have been selected as the key wave guiding structures for the implementation of low loss, high quality factor and improved selectivity waveguide bandpass filters on printed circuit board (PCB) technology. In addition, taking into account the possibility of having forward wave propagation below the waveguide cutoff frequency, the substrate integrated waveguide has been combined with complementary split ring resonators (CSRR) for the implementation of compact size and high selectivity bandpass filters [7].

An Omnidirectional Wrappable Compact Patch Antenna for Wireless Endoscope Applications

An inductively loaded compact patch antenna for a radiation frequency of 433 MHz is designed taking into consideration a human-body model and fabricated on a flexible liquid crystalline polymer (LCP) substrate, which is subsequently wrapped into a cylindrical shape to achieve a monopole-like omnidirectional radiation pattern for wireless endoscope applications. The wrapped patch antenna has a stretched length of 31 mm (0.07λg), and its cylindrical form has a diameter of 10 mm and a width of 18.5 mm, whose dimensions are designed to be comparable to those of a commercially available capsule endoscope. Compared to a traditional patch antenna with the same radiation frequency, an 86% length reduction is achieved. Omnidirectionality is desired to increase the space coverage in communication between the randomly moving capsule inside and the receiver outside the body. The enclosed cylindrical cavity, surrounded by the ground plane of the patch, provides an electromagnetic interference (EMI) protected room that is useful for the placement of other electronic components. Multiple inductive notches on a patch designed for antenna size reduction are described by an equivalent circuit model. Human-body phantom solution is used for antenna characterization. The antenna, located at the outermost layer, serves not only as a good radiating unit, but also as the EMI protecting, mechanically supporting, packaging layer of the endoscope system.

Wireless passive sensing application using a cavity loaded evanescent mode half mode substrate integrated waveguide resonator

In this work, an evanescent mode half mode substrate integrated waveguide (HMSIW) resonator is designed for a wireless passive sensing application at 5 GHz. The wireless pressure sensor has been implemented by placing a small Polydimethylsiloxane (PDMS) cavity, covered with a metal coated membrane, on top of the original resonator or by using a cavity ground plane. When the metal coated membrane is deformed or deflected by an external pressure, it perturbs the electric field of a complementary split ring resonator (CSRR) patterned on top of the HMSIW, producing a shift in the resonance frequency. Because it operates in a microwave frequency spectrum, it offers a high pressure-frequency sensitivity. Resonance frequency as a function of an applied pressure has been presented. Also, a broadband antenna has been integrated to perform wireless interrogation of the sensor.

Rectangular waveguide shape folded patch antenna

A microstrip patch antenna is one of the most popular resonance antennas due to its light weight and easy fabrication and therefore widely used for many commercial electronic devices such as GPS receivers and for military applications such as airborne and aerospace communication [1]. A conventional patch antenna is constructed by two metallic layers which are separated by a thin dielectric layer. The upper metallic layer is responsible for radiation while the lower one works as the ground plane blocking electromagnetic (EM) waves propagating to the ground plane direction. Since the patch antenna shows good directivity in the broad side of the upper patch, electronic circuitry placed behind the ground plane would have little electromagnetic interference (EMI) from patch antenna radiation.

Cylindrical radial superlattice conductors for low loss microwave components

Theory and experimental demonstration of a cylindrical radial superlattice (CRS) conductor composed of alternating nanoscopic non-ferromagnetic/ferromagnetic metal layers are presented with focus on low conductor loss in a K-band microwave spectrum. The dynamic frequency response of the ferromagnetic thin films has been extracted using the Landau-Lifshitz-Gilbert equation which shows a negative magnetic permeability value in the frequencies above its ferromagnetic resonance. The reduction of the conductor loss results from the eddy current canceling (ECC) effect in the CRS conductors, where the negative-permeability ferromagnetic and positive-permeability non-ferromagnetic metal layers produce a zero effective permeability, resulting in virtually infinite skin depth at the targeted frequency. The closed and uniform boundary conditions inherent in the radial shape conductors preclude discontinuity effects occurring at the edges of the planar superlattice conductor and end up with a more effective ECC effec...

A compact self-packaged patch antenna with non-planar complimentary split ring resonator loading

A self-packaged folded patch antenna in a rectangular waveguide shape is greatly reduced in size by loading a complimentary split ring resonator (CSRR) on the edge of its ground plane. The dimensions of the proposed antenna are 15mm×15mm×20mm, showing 72% volume reduction compared to one without CSRR loading at the same radiation frequency of 2.4GHz. Impedance matching between the patch and the feeding line is obtained by adjusting the gap between two edges of the folded patch not necessitating an additional impedance matching circuit. Also, the inside cavity surrounded and packaged by the folded patch is electromagnetically well shielded from the external circuit. This antenna offers a quasi-omni-directional radiation pattern. All those features make the proposed antenna very suitable for a compact sensor network application. To our knowledge, this is the first report a non-planar CSRR applied to antenna size reduction.

Electrically small tunable split ring resonator antenna

Since its physical implementation in 1999 by Pendry et al. [1], metamaterials which demonstrate negative permittivity and permeability have been raised as an interesting research topic in the microwave society for their unique features. Split ring resonator (SRR) is one of the most popular structures which could introduce negative permeability. Usually, a SRR is composed of two homocentric metallic rings, where each of them has a slot on the ring. The SRR works as an L-C resonance network whose resonance frequency can be determined by [2]

Compact spiral antennas for MICS band wireless endoscope toward pediatric applications

Endoscopy is a medical procedure carrying out in-vivo tests [1]. The conventional wired endoscopy process is pain staking and time consuming. An alternative to this wired one would be a wireless endoscope system. Various pill type endoscopes such as iPill [2], Sayaka [3], and Smart Pill [4] have been developed for drug delivery, imaging, and pH sensing in the stomach and intestines. The current device size of approximately 10mm × 20mm allows the usage of products only for a human adult as the average diameter of adult upper esophagus of approximately 13mm is large enough to accommodate such devices [5] while they are too big for children. To extend the usage of such wireless endoscopy to pediatric applications, pill should be greatly reduced in size. For instance, a standard small ‘Size 1’ capsule [6] with a dimension of 6.91mm × 19.4mm would be appropriate.