Kyungho Chung

Wideband microstrip-fed monopole antenna having frequency band-notch function

A novel and compact ultra-wideband (UWB) microstrip-fed monopole antenna having frequency band notch function is presented. To increase the impedance bandwidth of an antenna, a narrow slit is used. By inserting a modified inverted U-slot on the proposed antenna, the frequency band notch characteristic is obtained. The designed antenna satisfies the voltage standing wave ratio requirement of less than 2.0 in the frequency band between 3 and 11 GHz while showing the band rejection performance in the frequency band of 5.0 to 5.9 GHz.

Design of an ultrawide-band TEM horn antenna with a microstrip-type balun

An exponentially tapered ultrawide-band transverse electromagnetic (TEM) horn antenna having a microstrip-type balun is designed. The balun is used to improve the impedance characteristic of a TEM horn antenna. The measured bandwidth for VSWR less than 2.0 ranges from 67.94 to 1573.9 MHz. The bandwidth of the proposed TEM horn is three times wider than that of the linearly tapered TEM horn. The designed antenna can be used not only for electromagnetic compatibility measurement but also for broad-band communication system.

Design of a planar inverted-F Antenna with very wide impedance bandwidth

This letter presents a novel wideband planar inverted F-antenna, which covers GSM850/DCS1800/DCS1900/ IMT2000/WLAN/DMB services at the same time. The proposed antenna consists of a main patch with a pair of slant slits and L-shaped patch and occupies a total volume of 15times44times8mm3. The triple frequency bands are obtained by changing the length and width of a slant slit 1 on the main patch. A very wide impedance bandwidth characteristic is achieved by optimizing not only the length and height of a L-shaped patch between the main patch and ground plane but also the length and width of a pair of slits on the main patch which is excited by the modified coplanar waveguide-feed. Good broadside radiation patterns are achieved for all six-frequency bands of interest

Ultra-wideband low noise amplifier using a cascode feedback topology

An ultra-wideband (UWB) low noise amplifier (LNA) that consists of two cascode and shunt feedback stages is presented. Measurement results show the maximum power gain (S/sub 21/) of 11.9 dB with the 3-dB band from 2 to 6.5 GHz and input/output reflection coefficient (S/sub 11/, S/sub 22/) of less than -7.8 dB from 2 to 11 GHz. In addition, the fabricated LNA achieves the average noise figure (NF) of 4.5 dB from 2 to 10 GHz, which value is much lower than previously reported state-of-the-art UWB amplifiers. The input-referred third-order intercept point (IIP3) and the input-referred 1-dB compression point (Pub) of the LNA are achieved as 4 dBm and -5 dBm, respectively, while consuming 27 mW in 0.18 /spl mu/m RF CMOS process.

Design of a wideband TEM horn antenna

A novel design method for a TEM horn antenna is proposed on the basis of parallel plate waveguide theory. This TEM horn antenna has an exponentially tapered structure to increase the matching bandwidth. The measurement shows that the TEM horn antenna has the frequency band of 75 MHz to 1200 MHz for VSWR less than 2.0.

Compact wideband printed monopole antenna with frequency band-stop characteristic

A novel compact and wideband printed monopole antenna with frequency band-stop characteristic is presented. By embedding a notch in the ground plane, the ultrawideband property for the proposed antenna is achieved. To create a frequency bandstop characteristic, a simple /spl lambda//4 U-shape slot is inserted into the radiating patch. Numerical and experimental results show that the proposed antenna operates over 2.95 to 11.7 GHz for VSWR<2, while the band-stop characteristic is maintained in the frequency band of 4.92 to 5.86 GHz.

Design of a microstrip-fed ultra-wideband monopole antenna having band rejection characteristic

A new compact and microstrip-fed ultra-wideband (UWB) monopole antenna having band rejection characteristic is proposed. By using tuning stub and stepped ground, the antenna provides an enhanced impedance bandwidth. The band stop characteristic is realized using an inverted-U shaped slot. The range of stop band can be adjusted by changing the length and width of the inserted slot. The measured impedance bandwidth of the proposed antenna ranges from 2.9 GHz to 12.1 GHz for VSWR < 2 while having the band rejection characteristic in the frequency band of 4.9 GHz to 6 GHz. This antenna shows a monopole-like radiation pattern and flat gain characteristic throughout the operating frequency band.

The design of a wideband TEM horn antenna with a microstrip-type balun

An exponentially tapered wideband TEM horn antenna having a microstrip-type balun is designed. The balun is used to improve the impedance characteristic of the TEM horn antenna. The measured VSWR is less than 2.0 from 81 MHz to 1310 MHz. The designed antenna can be used not only for EMC measurements, but also for broadband communication systems.

Design of a band-notched wideband antenna for UWB applications

A simple and compact microstrip-fed ultrawide-band (UWB) printed monopole antenna with band-notch characteristic is proposed. The antenna is composed of two monopoles of the same size and a small strip bar which leads to the desired high attenuation at the notch frequency. Details of the antenna design are presented and discussed. The band-notch mechanism and current distribution of the antenna are examined. Finally, the frequency-domain characteristics are analyzed to evaluate the antenna performance for UWB applications