Michael Bank

The Development of a Cellular Phone Antenna with Small Irradiation of Human-Organism Tissues

The method put forward here is to reduce undesirable irradiation using an auxiliary radiator of low power. Calculations show that an arrangement with an additional radiator reduces irradiation by a factor of three to four. The structure and magnitude of the field in the far zone preserve their quality of communication with the correspondents (base stations) in all directions.

On increasing OFDM method frequency efficiency opportunity

OFDM-SFN or OFDM-MFN methods are used in DVB-T and DAB systems. In the case of MFN there are problems with frequency efficiency. This article presents a new multiplexing technique, which combines OFDM and CDMA features. It solves some problems of these methods. This new method solves some of the problems of OFDM-MFN and other wireless OFDMA systems, namely increasing frequency efficiency.

Cellular Phone Antenna with a Small Irradiation of the Human Head

A compensation method for reducing the irradiation of the head of a cellular phone user without degradation of the far field is analyzed. This method uses two radiators that are located in the near region of each other, and create a weak field area in this region. The impacts of the mutual coupling between closely located radiators on the input impedance, current distribution, and fields of the radiators are studied. It is shown that the structure of two closely spaced monopoles is equivalent to the superposition of two basic structures: a two-wire open-ended line, and a single monopole. The shape and dimensions of the dark spots and the irradiation-reduction factor are determined. To facilitate the field calculations in the near zone of the antennas, a method based on replacing a piecewise-homogenous medium by an equivalent homogenous medium is used. The calculations and the experimental results in the presence of the head qualitatively agreed.

On some misunderstandings using a dipole or monopole

This paper is an attempt to draw attention to frequently occurring mistakes in comparing a dipole to a monopole, and in explaining the antenna/transmitter impedance-matching problem for noise-figure optimization.

A simple odd-symmetric filter for digital broadcasting

A new odd-symmetric filter for ISI suppression and VSB transmission is proposed. The frequency response of the proposed filter is similar to that of an ideal raised-cosine filter, but in contrast to raised-cosine the new filter is realizable, e.g. using simple active filters. Simulation results show that concerning ISI suppression the new filter is significantly more efficient than the classical Butterworth or Chebyshev filters. The proposed filter can be also used as a VSB filter for TV modulators and demodulators.