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A broadband probe-fed patch antenna with a novel three-dimensional (3D) U-shaped ground plane is proposed and experimentally studied. The proposed antenna has a thick air substrate, and by placing the two flanges of the U-shaped ground plane in parallel to and at a suitable distance from the radiating edges of the antenna's radiating patch, a wide impedance bandwidth (>25%) with much reduced cross-polarization radiation can be obtained, compared to the case with a conventional planar ground plane. In addition, enhanced antenna gain for the proposed antenna is also observed. Details of the proposed antenna and experimental results are presented and discussed.

The printed loop antenna for multi-frequency operation in the mobile phone application is proposed. The loop antenna consists of an inverted-L shaped strip and a rectangular patch on the front side, while the back side consists of a meander loop antenna and a 100×60 mm2 ground plane. The inverted-L shaped strip and the rectangular patch are connected with a 50 Ω microstrip line. The feeding mechanism is coupled-fed method, which excites the loop antenna through the inverted-L strip and the rectangular patch. The loop antenna provides two wide operating bands centered at about 810 and 2175 MHz for LTE700/GSM850/GSM900/DCS/PCS/UMTS/LTE2300/WLAN/LTE2500 bands operation. The proposed antenna also has the advantages of low profile, low cost, ease fabrication, and less affected by changing ground plane size.

This paper presents a design using dual capacitive feeds to excite a patch antenna with a thick air substrate to achieve a wide operating bandwidth with reduced cross-polarization radiation. The dual capacitive feeds are fed by equal input powers, but with a 180° phase shift, and have a narrow conducting strip placed below the radiating patch, supported by a conducting post, which is then connected, through via holes in the ground plane, to the microstrip feed network. Experimental results show that the proposed antenna can have greatly reduced cross-polarization radiation across the entire operating bandwidth, compared to the case with a single capacitive feed. Details of the proposed antenna and experimental results are presented. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 169–171, 2000.

The planar monopole antenna with a parasitic shorting stub is printed on the double-side FR4 substrate, with thickness 0.4 mm and relative permittivity 4.4, and fed by a 50 Ω microstrip line. The antenna patch has the size of 23 × 10.2 mm2 and consists of two resonant elements, a T-like monopole and a parasitic shorting stub. Due to the reduced size and capable of multiple operating bands, including 1.8, 1.9, 2.0, 5.2 and 5.8 GHz, it can be used in multi-band mobile phone for DCS (Digital Communication System), PCS (Personal Communication System), UMTS (Universal Mobile Telecommunications System) and UNII (Unlicensed National Information Infrastructure) 5-GHz radio band applications. Details of the proposed antenna design are described in the follow, and experimental results of the constructed prototype are presented.

A new and simple technique for obtaining circular polarization (CP) radiation of a single-feed microstrip antenna is demonstrated. This CP design is achieved by insetting a single slit to the boundary of the microstrip patch, and placing a single feed along an axis 45° to the one containing the slit. Applications of this CP design method to square and circular microstrip antennas have been implemented. Typical experimental results are presented and discussed. © 1998 John Wiley & Sons, Inc. Microwave Opt Technol Lett 18: 306–308, 1998.

A variety of dual-frequency microstrip antennas have been previously reported. However, it is noted that these dual-frequency designs usually support limited tunable frequency ratios for the two operating frequencies. To provide a very flexible frequency ratio for a single-feed dual-frequency microstrip antenna, the design with two circular patches has also been shown. Such a design, however, uses a relatively complicated matching network between the two patches. We present a new structure of using an inset-microstrip line to simplify the matching network, which makes the present proposed design simpler and easier to be constructed. The proposed design method applied to two rectangular patches has been successfully implemented. The obtained frequency ratio of the two operating frequencies can be flexible, and good dual-frequency performances are also observed. Details of the antenna design and experimental results are presented and discussed.

Broadband patch antennas with a thick air or foam substrate have been of considerable interest owing to their simple structure, easy fabrication, and good radiation characteristics over a wide operating bandwidth. However, when such broadband patch antennas are to be excited using a probe feed, achievable bandwidth is usually limited to be less than 10%, due to the large inductance associated with the longer probe in the thick substrate layer. To overcome this problem, there are usually some compensations or modifications to be introduced in the feed arrangement or some slot loadings to be added to the radiating patch. In this article we demonstrate a new and simple broadband design of a patch antenna with a pair of wide slits. The wide slits are inserted at the boundary of a circular patch or at one of the radiating edges of a rectangular patch. The proposed broadband patch antenna can have similar wide impedance bandwidth and good radiation characteristics as those reported for a U-slotted patch antenna. Details of the antenna design and experimental results are presented and discussed.

A broadband shorted-patch antenna fed by an aperture-coupled feed with an H-shaped coupling slot is proposed and experimentally studied. By using an air substrate with a thickness of about 0.07 of the free-space wavelength of the center operating frequency, the proposed antenna can have an impedance bandwidth of about 26.2%, which is comparable to the conventional broadband probe-fed patch antenna with a U-slotted or E-shaped patch. Good broadside radiation patterns for the proposed antenna are also observed. Details of the proposed antenna and experimental results are presented. © 2001 John Wiley & Sons, Inc. Microwave Opt Technol Lett 28: 306–307, 2001.

A new design of a circular patch antenna with an impedance bandwidth greater than 25% and a peak antenna gain about 8.3 dBi is presented. The circular patch antenna has a thick air substrate, and a pair of wide slits are cut in the circular patch to facilitate the antenna's impedance matching. The circular patch is supported by a conducting post, which is also connected to a 50 Ω microstrip feed line. The ground plane of the microstrip line also serves as the ground plane of the circular patch antenna, and the substrate of the microstrip feed line and the circular patch are on the same side of the ground plane. Details of the antenna design and experimental results are described. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 327–328, 2000.

A wideband circular-E patch antenna with an air substrate and a capacitive feed is proposed. The circular-E patch is formed by inserting a pair of wide slits at the boundary of a circular patch, and the capacitive feed has a small metallic disk placed below the circular-E patch, supported by a conducting post, which is then connected to a 50 Ω SMA connector through a via hole in the ground plane of the patch antenna. A prototype of the proposed antenna is constructed, and experimental results reveal that a group of three adjacent resonant modes can be excited, which results in a wide 10 dB return-loss impedance bandwidth of about 35%. Acceptable radiation characteristics for operating frequencies across the obtained wide impedance bandwidth are also observed, and the gain variation within the bandwidth is seen to be less than 1.4 dBi, with a peak antenna gain of about 7.9 dBi. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 134–135, 2000.

Novel design of a dual-frequency triangular microstrip antenna with a V-shaped slot is proposed and experimentally studied. By selecting suitable dimensions of the V-shaped slot, dual-frequency operation with the frequency ratio ranging from 1.488 to 1.834 has been obtained using a single probe feed, and the two operating frequencies are of parallel polarization planes. Typical experimental results of the proposed design are presented and discussed. ©1999 John Wiley & Sons, Inc. Microwave Opt Technol Lett 20: 133–134, 1999.

A novel disk-sector microstrip antenna with specific flare angles for circular polarisation (CP) operation is proposed and experimentally studied. Results show that by selecting the flare angle of the disk-sector microstrip patch to be 65 or 70/spl deg/, right hand or left-hand CP radiation can easily be obtained using a single probe feed. Details of the design considerations are described, and measured CP characteristics are presented.

The broadband design of a triangular microstrip antenna with a U-shaped slot is demonstrated. With a foam substrate of thickness /spl sim/0.08 /spl lambda//sub 0/, a slotted triangular microstrip antenna with an operating bandwidth of /spl sim/18% is obtained, which is /spl sim/1.8 times that of a corresponding simple triangular patch antenna. Details of the antenna design and experimental results are presented.