Byoung Moo Lee

A single-feeding circularly polarized microstrip antenna with the effect of hybrid feeding

A single series feed cross-aperture coupled microstrip antenna with the effect of hybrid feeding is proposed and demonstrated. To understand this antenna better, the characteristics according to the variation of parameters are shown. This proposed antenna has the following advantages of the effect of hybrid feeding: improved axial ratio bandwidth (4.6%); high gain (8 dBi); flat 3 dB gain bandwidth (above 16.7%). In measured radiation patterns, we have 3 dB beamwidth of /spl plusmn/30/spl deg/ and good F/B (front to back ratio) of 20 dB.

A harmonic suppression antenna for an active integrated antenna

An inset-fed antenna with a shorting pin and slots is presented for harmonic suppression of an active integrated antenna. Its fundamental resonant frequency is 5.8 GHz. At fundamental and harmonic frequencies, return loss and radiation characteristics are measured and compared with those of the conventional microstrip patch antenna. The second and third harmonic return losses of the proposed antenna are suppressed to 6.7 dB and 17.7 dB with respect to the conventional patch antenna, respectively.

A dual fed and a dual frequency slots-loaded triangular microstrip antenna

As the advances in wireless communication technology are very rapid, there have been vast research in dual fed microstrip antennas in order to isolate the Tx and the Rx signals and for a variable profile dual frequency patch. For example, the study of dual frequency operation has been carried out with the via-hole feed and microstrip line feed. Using a dual resonant microstrip antenna would be better than the broadband microstrip antenna, because it is very difficult that a single layer microstrip antenna has a bandwidth which covers the up- and down-link of the IMT-2000 system. In this article, a dual resonant triangular microstrip antenna with slots-loaded and the characteristics of the isolation between the Tx and the Rx ports using inset microstrip line feed and probe feed methods are proposed and experimentally studied for the case of a thin substrate.

X-band TM/sub 01/-TE/sub 11/ mode converter

This paper presents a direct TM/sub 01/-TE/sub 11/ small mode converter using a circular waveguide with tilted structure for X-band high power microwave system. It is designed to transmit microwave energy from a relativistic backward-wave oscillator (RBWO) source to horn antenna effectively, with optimized geometry through a parameter study. The simulated and measured results of return loss, fractional power of each mode, impedance bandwidth, and mode pattern are provided.