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Two types of broad-band antennas are widely used for electromagnetic interference (EMI) measurements in the frequency range from 30 to 1000 MHz. Log-periodic dipole antennas (LPDA) are mainly used for the range above 300 MHz and biconical antennas for the range less than 300 MHz. These two antennas have linear polarization. However, EMI measurements can sometimes be more conveniently made with an antenna having circular polarization and so we propose an improved LPDA, which has circular polarization. This LPDA has a second array of dipoles so arranged that each dipole of the second array has a quarter-wavelength phase difference from that of the corresponding dipole of the standard LPDA array for the given radiation field. For this reason, we named it a crosselement LPDA. The cross-element LPDA does not need a broadband 90 hybrid junction to produce circular polarization. We calculated the height pattern and the frequency characteristics of the classical site attenuation (CSA) for the cross-element LPDA when used for both transmitting and receiving, as well as the antenna factor. Moreover, we calculated the normalized site attenuation (NSA) when the cross-element LPDA is used for receiving or for both transmitting and receiving.

, the first micro-laser propulsion onboard the KKS-1 microsatellite was deployed in space as a piggyback payload to the Greenhouse Gases Observing Satellite called "Ibuki." An in-space test was planned using laser propulsion; however, due to a malfunction of the onboard CPU, the test was delayed until the recovery of the KKS-1. In this paper, current satellite trends toward smaller and lighter satellites are briefly summarized. We also propose micro and laser propulsion that operates in two modes (laser ablation and ignition) as a promising candidate to meet versatile requests for future microsatellite missions.

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