|dc.description.abstract||In this study, a portable wireless communication system with low power-consuming and compact size is presented. The module is composed of a transmitter and a receiver. The transmitter consists of oscillator and antenna. The receiver consists of antenna, bandpass filter, low noise amplifier, AC/DC modulation, and power density display. The proposed system features easily assembling and disassembling components since they connect one another by SMA connectors. Users can replace the existing components to meet the demands for various teaching goals. Furthermore, there is no power amplifier in the entire system. Power is transmitted directly from oscillator to antenna. To implement the lowest power-consuming structure, the output DC connects to LM3914C for detecting minor voltage, which needs no amplifier.
The operating frequency of the module is designed at 1.59 GHz. For the oscillator, the input voltage is 3 V and the current is 6 mA. The power supply is used by cascading two 1.5 V batteries and the output power is of 9.3 dBm. For the antenna, patch antenna and dipole antenna are provided to exchange. For the bandpass filter, the dual-mode bandpass filter is employed. It consists of one wavelength ring and two capacitors for feeding. For the low noise amplifier, the input voltage is 3 V and the current is 6 mA. The power supply is used by cascading two 1.5 V batteries and the output power is of 19 dB. For the AC/DC modulation, one order voltage doubler is used to modulate the signal from AC to DC. To display the wireless signal density, thirty LEDs are arranged to shine. As signal density is more powerful, more LEDs are turned on. The operating current is 394 mA as all LEDs shine. The driven voltage is of 5 V. The whole system can be charged up by using laptops or rechargeable battery kits with USB connector.||en_US|