We present small sinusoidal printed monopoles as enhanced meander-line antennas shaped after smooth curves. The antennas were designed at 2-3 GHz according to the size and bandwidth constraints of multimedia sensor networks. Their performance was characterized in terms of electrical size, bandwidth, and broadband radiation efficiency. A suitable scalar quantity was used to capture the overall performance. Results show that the sinusoidal monopole achieves 68% more bandwidth compared to a meander-line antenna of similar size and efficiency. Antenna performance depends heavily on electrical size, which depends on the size of the ground plane; its effect on radiation was also studied.

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Mini-satellite (100-500 kg) 2. Micro-satellite (10-100 kg) 3. Nano-satellite (1-10 kg) 4. Pico-satellite (0.1-1 kg) 5. Femto-satellite (0.01-0.1 kg) CubeSats belong to the genre of pico-satellites; their maximum weight lies on the borderline between pico-and nano-satellites. The main reason for miniaturizing satellites is to reduce the cost of deployment: heavier satellites require larger rockets of greater cost to finance; smaller and lighter satellites require smaller and cheaper launch vehicles, and are often suitable for launch in multiples. They can also be launched "piggyback", using the excess capacity of larger launch vehicles (Wikipedia, 2010b). But small satellites are not short of technical challenges; they usually require innovative propulsion, attitude control, communication and computation systems. For instance, micro-/nano-satellites have to use electric propulsion, compressed gas, vaporizable liquids, such as butane or carbon dioxide, or other innovative propulsion systems that are simple, cheap and scalable. Micro-satellites can use radio-communication systems in the VHF, UHF, L-, S-, C-and X-band. On-board communication systems must be much smaller, and thus more up-to-date than what is used 12 in conventional satellites, due to space constraints. Furthermore, miniature satellites usually lack the power supply and size required for conventional bulky radio transponders. Various compact innovative communication solutions have been proposed for small satellites, such as optical (laser) transceivers, antenna arrays and satellite-to-satellite data relay. Electronics need to be rigorously tested and modified to be "space hardened", that is, resistant to the outer space environment (vacuum, microgravity, thermal extremes and radiation exposure) (Wikipedia, 2010b). The CubeSat programme was developed through the joint efforts of research laboratories from California Polytechnic State University (Cal Poly) and Stanford University, beginning in 1999. The concept was introduced to the scientific community as an opportunity for all universities to enter the field of space science and exploration. A large group of universities, along with certain companies and organizations, participate actively in the CubeSat programme; it is estimated that 40 to 50 universities were developing CubeSats in 2004. Featuring both small size and weight, a CubeSat can be built and launched for an estimated total of $65,000-80,000 (per fiscal year 2004 values). The standard 10 × 10 × 10 cm 3 basic CubeSat is often called a "1U" CubeSat, meaning one unit. CubeSats are roughly scalable in 1U increments and larger. The four basic sizes are 0.5U, 1U, 2U and 3U. The number corresponds to the length of the CubeSat in decimetres; width and depth are always 10 cm, or 1 dm. Orbiters such as a "2U" CubeSat (20 × 10 × 10 cm 3) and a "3U" CubeSat (30 × 10 × 10 cm 3) have been both built and launched. Since CubeSats are all 10 × 10 cm 2 (regardless of length) they can all be launched and deployed using a common deployment system. CubeSats ar...