We present results from two observations of the cosmic microwave background (CMB) performed from the South Pole during the 1993-1994 austral summer. Each observation employed a 3◦ peak to peak sinusoidal, single difference chop and consisted of a 20◦ × 1◦ strip on the sky near our SP91 observations. The first observation used a receiver which operates in 3 bands between 38 and 45 GHz (Q-band) w...

The influence of microwave oven interference on IEEE802.11 Wireless Local Area Network (WLAN) performance is a significant factor because they share common spectrum in the 2.400 2.4835 GHz Industry, Science, and Medicine (ISM) band. FCC regulations permit radiated power of up to 1 watt in this band provided spread spectrum techniques are employed. Spread spectrum methods facilitate multiple use...

In this paper, a new design of optical channel drop filter based on two- dimensional photonic crystal ring resonators with triangular lattice is proposed. The rods of this structure is silicon with the refractive index 3.46 and the surrounding environment is air with the refractive index of 1.The widest photonic band gap obtained is for filling ratio of r/a = 0.2. The filter’s transmission spec...

In this article, the effect of cells' radius on the behavior of wavelength switching optical filter andthe effect of the radius of the optical filters' key characteristics such as wavelength resonance onan optical filter based on photonic crystals, have been investigated. Currently, the most commonapplied mechanism for designing optical filter based on photonic crystals is using twomechanisms s...

Spectrum scarceness is one of the major challenges that the present world is facing. The efficient use of existing licensed spectrum is becoming most critical as growing demand of the radio spectrum. Different researches show that the use of licensed are not utilized inefficiently. It has been also shown that primary user does not use more than 70% of the licensed frequency band most of the tim...

__________ Many mobile satellite systems have been proposed to employ Code Division Multiple Access (CDMA) technique at L/S band. These bands have been allocated to the mobile satellite services on a primary basis since 1992, in addition to the existing services. Therefore, the mobile satellite services will be subject to share spectrum with each other and with existing services. This paper dis...

The spectrum allocation policies of the Federal Communications Commission (FCC) [1] only allow spectrum access to primary users, it has been proven by various spectrum measurement campaigns that, the current spectrum usage across time and frequency is inefficient. Therefore, in order for the secondary users to access the unused portions of the licensed spectrum, the concept of “spectrum pooling...

We present an analysis of the ROSAT and ASCA spectra of 21 broad line AGN (QSOs) with z ∼ 1 detected in the 2-10 keV band with the ASCA GIS . The summed spectrum in the ASCA band is well described by a power-law with Γ = 1.56± 0.18, flatter that the average spectral index of bright QSOs and consistent with the spectrum of the Xray background in this band. The flat spectrum in the ASCA band coul...