Sang Heun Lee

A Wideband Spiral Antenna for Ingestible Capsule Endoscope Systems: Experimental Results in a Human Phantom and a Pig

This paper presents the design of a wideband spiral antenna for ingestible capsule endoscope systems and a comparison between the experimental results in a human phantom and a pig under general anesthesia. As wireless capsule endoscope systems transmit real-time internal biological image data at a high resolution to external receivers and because they operate in the human body, a small wideband antenna is required. To incorporate these properties, a thick-arm spiral structure is applied to the designed antenna. To make practical and efficient use of antennas inside the human body, which is composed of a high dielectric and lossy material, the resonance characteristics and radiation patterns were evaluated through a measurement setup using a liquid human phantom. The total height of the designed antenna is 5 mm and the diameter is 10 mm. The fractional bandwidth of the fabricated antenna is about 21% with a voltage standing-wave ratio of less than 2, and it has an isotropic radiation pattern. These characteristics are suitable for wideband capsule endoscope systems. Moreover, the received power level was measured using the proposed antenna, a circular polarized receiver antenna, and a pig under general anesthesia. Finally, endoscopic capsule images in the stomach and large intestine were captured using an on-off keying transceiver system.

Fat arm spiral antenna for wideband capsule endoscope systems

In this paper, a new antenna for wideband capsule endoscope systems is introduced. The antenna that is supposed to operate in human body has fat arm spiral structure to achieve small size and wideband characteristics. Since capsule endoscope systems are designed to operate in the human body and its front end transmits internal image data to an external receiver with high resolution, a wideband and small antenna is required. Moreover, to operate in the human body, the frequency of the proposed antenna is determined from the electrical properties of body materials. The bandwidth of the proposed antenna is 460 ∼ 535 MHz (75 MHz) for VSWR ≪ 2 and it has omni-directional radiation pattern. The height of the proposed antenna is 4 mm and diameter is 10 mm. Because of wideband characteristic and small size, the proposed antenna is suitable for wideband capsule endoscope systems.

Multiband Folded Slot Antenna With Reduced Hand Effect for Handsets

In this letter, a multiband handset antenna using folded slots is proposed to support the five wireless communication bands of GSM850 (824-894 MHz), GSM900 (880-960 MHz), DCS1800 (1710-1880 MHz), PCS1900 (1850-1990 MHz), and UMTS (1920-2170 MHz). Since the proposed antenna has balanced resonating characteristics, resonant frequency shifting due to the hand effect is reduced while allowing a small size of 40 × 18 × 7 mm3 (W × L × H). As a result, the improved matching characteristic at the operating frequency band reduces the degeneration of the radiation efficiency due to the hand effect.

A dual spiral antenna for Ultra-wideband capsule endoscope system

In this paper, a dual spiral antenna for ultra-wideband capsule endoscope system is proposed. Since a capsule endoscope system which transmits real-time image data in the body should have ultra-wideband characteristic, an ultra-wideband antenna is suitable for this system. When an antenna is used as capsule endoscope system, a small sized antenna is required because capsule is small enough to be swallowed. For these two conditions, the proposed antenna has dual resonance structure which is composed of two different spiral elements and single feed wire connects these two elements. The bandwidth of the proposed antenna is 411~600 MHz (189 MHz) for VSWR<2 which means the fractional bandwidth of 37.8% and it has isotropic radiation pattern. The height of the proposed antenna is 7 mm and diameter is 10 mm. Because of ultra-wideband characteristic and small size, the proposed dual spiral antenna is suitable for ultra-wideband capsule endoscope system.

A conical spiral antenna for wideband capsule endoscope system

In this paper, a conical spiral antenna for wideband capsule endoscope system is proposed. To design an antenna in the human body, operating frequency of the proposed antenna is determined by considering the electrical properties of body materials. The bandwidth of the proposed antenna is 418~519 MHz (101 MHz) for VSWR<2 which means the fractional bandwidth of 22% and it has omni-directional radiation pattern. The height of the proposed antenna is 5 mm and diameter is 10 mm. Because of ultra-wideband characteristic and small size, the proposed conical spiral antenna is suitable for ultra-wideband capsule endoscope system.

Mode Conversion of High-Power Electromagnetic Microwave Using Coaxial-Beam Rotating Antenna in Relativistic Backward-Wave Oscillator

Mode conversion of high-power electromagnetic microwave (HPEM) was successfully accomplished using a coaxial-beam rotating antenna (COBRA) in an X-band relativistic backward-wave oscillator (RBWO). The mode conversion from the TM01 mode to the circularly polarized TE11-likeness mode was identified by both cold test and hot test. To observe whether mode conversion is effective or not, the radiation pattern of TE11-likeness mode by COBRA lens was compared with the case of the radiation pattern of TM01 mode using simple horn antenna. Their radiation patterns could be described by fluorescent lamps. The experimental results of radiation pattern measurements are shown to be in a reasonable agreement with the simulated one. The maximum value of RF output power appeared at the center of COBRA lens from the experimental results.

Multi-band coupled feed loop antenna for mobile handset

In this paper, a multi-band coupled feed loop antenna for mobile handset is proposed. This antenna is composed of a feed element and a radiating element. The antenna is printed on the very thin flexible substrate to mount on the dielectric carrier with a volume of 2 cc. The bandwidth of the proposed antenna is 134MHz (866 – 1000 MHz) and 450 MHz (1692 – 2142 MHz). As a result, the proposed antenna covers the three bands of GSM 900, DCS 1800 and PCS 1900 for a 3:1 VSWR. Moreover, the radiation pattern and gain is appropriate for mobile handset. Therefore, this antenna is suitable for small sized multi-band mobile handset applications.

Internal mobile antenna for LTE / GSM850 / GSM900 / PCS1900 / WiMAX / WLAN

An internal mobile antenna covering multiband for LTE (746 – 806 MHz), GSM850 (824 – 894 MHz), GSM900 (880 – 960 MHz), PCS1900 (1850 – 1990 MHz), WiMAX (3.4 – 3.6 GHz) and WLAN (5.15 – 5.85 GHz) frequency bands is proposed. In order to satisfy the operation at WLAN frequency band, a metal branch is placed near the feeding point. It is shown that the operation at low frequency bands (LTE / GSM850 / GSM900) can be achieved by increasing the length of the ground. Considering the size of the commercial mobile phones, more practical design which exhibits the similar effect that can be attained by increasing the length of the ground is proposed. The antenna was fabricated and its measured results of return loss and radiation patterns at each frequency bands are presented. FR4 substrate with relative permittivity of 4.4 was used. The overall size of the proposed antenna is 40 × 100 × 5 mm3.

A dual spiral antenna for wideband capsule endoscope system

In this paper, a dual spiral antenna for wideband capsule endoscope system is introduced. This dual resonance structure is composed of two different spiral elements and single feed wire connects these elements. When a spiral antenna is used as capsule endoscope system, a small sized antenna is required because capsule is small enough to be swallowed. The impedance bandwidth of the proposed antenna is 98 MHz and it has isotropic radiation pattern. Therefore, the proposed dual spiral antenna is suitable for wideband capsule endoscope system.

Meander line loop antenna with coupled feed for multiband mobile phone

In this paper, the small loop antenna with coupled feed for multiband mobile phone is proposed. This antenna is composed of a feed monopole, radiating loop and parasitic element. This antenna is printed on the very thin flexible substrate to mount on the dielectric carrier with a volume of 40 mm×10 mm×3 mm. The bandwidth of the proposed antenna is 592 MHz (785–1377 MHz) for low band and 361 MHz (1816–2177 MHz) for high band for a 3:1 VSWR. Thus, the proposed antenna covers the four bands of GSM850 (824–894 MHz), GSM900 (880–960 MHz), PCS (1850–1990 MHz), and UMTS (1920–2170 MHz). Moreover, the measured radiation pattern and gain are appropriate for mobile handset. Therefore, this antenna is suitable for small sized multiband mobile phone applications.