Takashi Minemura

Frequency tunable antennas for mobile phone for terrestrial digital TV broadcasting reception

In this paper, two types of loop antenna and a broadband T-shaped antenna with a switch mounted on one end of its conductor are proposed. A RF switch such as single port multi throw (SPMT) is chosen rather than variable capacitors for these proposed antennas. Variable capacitors such as a diode, however, are influenced by the radiation power of cellular phones. Moreover, a bias voltage should be controlled continuously to change its resonance frequency. Tunable antennas can be designed as a built-in antenna with the full frequency coverage. Simulations and experiments are conducted to clarify its operation

A study on loop antenna with uniform current distribution

A new antenna concept is proposed to improve and stabilize performance at the talk position of cellular telephones. Constant vertical average gain which is independent of its tilting angle and suppressed radiation toward an operator side can be realized by loop type antennas with uniform current distribution. The proposed square antenna of 0.54 /spl lambda/ circumference length with distributed capacitances is measured. Predictable results are obtained.