David Delaune

Simple satellite-tracking dual-band triangular-patch array antenna for ETS-VIII applications

The Japan Aerospace Exploration Agency (JAXA) will launch a geostationary satellite called Engineering Test Satellite-VIII (ETS-VIII) in 2005. ETS-VIII will conduct orbital experiments on mobile satellite communications at the S-band frequency, especially to support the development of a technology for the transmission and reception of multimedia information such as voice and images for land mobile systems. Various antennas have been developed for mobile satellite communications purposes, but these antennas have a complex composition. A simple satellite-tracking triangular-patch array antenna is proposed. The targeted minimum gain of the antenna is set to 6 dBic at an elevation of 48/spl deg/ in the Tokyo area for applications of a few hundred kbps. The antenna also should be designed as thin, compact, small and simple as possible, because it will be mounted on bullet train, ship or car roof.

A simple circularly polarized beam-switching patch array antenna for satellite communication

The performance of a simple beam-switching four-patch array antenna, radiating circular polarization at 2.6 GHz, is presented. This antenna generates a directive beam allowing the tracking of the signal emitted by a satellite. Two methods of feeding the antenna, to realize the beam-tracking, are analyzed. First, when the feeding source is switched off. Second, when one element is fed with a different phase than the others. This four-patch array antenna has good performances in terms of minimum gain, axial ratio and voltage standing wave ratio but also small size and low cost.

On the performances of simple circularly polarized beam-switching, 3-element and 4-element patch array antennas for mobile satellite broadcasting/communication

Two types of array antennas operating at the 2.6 GHz-band, which can be used for the MSB (mobile satellite broadcasting), are presented. Both are formed of square patches with truncated comers and generate circular polarization. After finding the value of substrate relative permittivity giving the best results, numerical simulations concerning the two antennas were performed. The first array antenna is made of three elements and aims at a reduced size. Its performance is satisfactory in terms of axial ratio in the elevation plane and in terms of minimum gain, but not at low elevation angle. Then a second array, composed of four patches, was analyzed and gave better results. The axial ratio is satisfactory and the minimum gain is better than for the first array, though still under the specification at low elevation angles. Extra simulations revealed that the minimum gain could reach the required 3 dBi at low elevation angles if one of the feeding sources is turned off. This case is still under investigation. As both antennas are interesting, depending on the user, and considering the promising results, it is planned to confirm them by performing measurements.

Circularly Polarized Rounded-Off Triangular Microstrip Line Array Antenna

SUMMARY The Japan Aerospace Exploration Agency (JAXA) plans to launch a geostationary satellite called Engineering Test Satellite VIII (ETS-VIII) in FY 2006. In this paper, a microstrip line array antenna, which has a very simple structure, is introduced to radiate a circularly polarized wave aiming at ETS-VIII applications. This antenna consists of a triangular conducting line with its vertexes rounded off, located above a ground plane, with a gap on one of its side to produce a circular polarization. The proposed antenna is analyzed by numerical simulations for a single element as well as for a three elements array configuration and the possibility of beam-switching in the azimuth space is experimentally confirmed in the latter case. It is found that by properly feeding the elements constituting the array antenna, for an elevation angle El = 48 ◦ in Tokyo area, three beams are created in the conical-cut direction with a minimum gain more than 6.6 dBic and an axial ratio less than 3 dB.

Simple Electronically-steered On-board Stacked-type Dual-band Patch Array Antenna for Engineering Test Satellite VIII Applications

In this paper, two simple electronically-steered on-board satellite-tracking circularly polarized stacked-type dual-band patch array antennas for mobile satellite communications are numerically investigated. The configurations of the novel antennas are shown and their performances are discussed. The first model is fed by probes while the second one is fed by microstrip line. The gain obtained for an elevation angle of 48 is 6.4 dBic at the receiving frequency and the gain is 5.7 dBic at the transmitting frequency for the former model. Additionally, the axial ratio at both frequencies is around 4 dB. Regarding the latter model, for the same elevation angle, the gain is 6.4 dBic for the transmission but only 3.3 dBic for the reception. However with this model the axial ratio is satisfactorily less than 3 dB.