在電子電機領域中，電波類的課程往往是非常抽象的，大多數的老師只能靠著定理推演及舉例來教導學生，為了加深學生對電波的印象，本文設計了低耗電、可攜式無線模組教學系統供老師所使用，整個系統可分為發射端及接收端兩部分，其中發射端是由振盪器及天線所組成；而接收端是由天線、濾波器、低雜訊放大器、交直流轉換器以及能量強度顯示器所組成，每一個單元都是以SMA做連結，可供使用者自行拆裝做更換。
本系統設計在1.59 GHz，振盪器的輸入驅動電壓設計在3 V，消耗電流為6 mA，採用1.5 V三號電池串連兩顆，輸出功率為9.3 dBm，在天線的部分，一共設計了左右手圓極化的微帶天線，以及線性極化天線供使用者更換。在低雜訊放大器的部分，輸入驅動電壓設計在3 V，消耗電流為6 mA，一樣採用1.5 V三號電池串連兩顆，放大增益為19 dB，在交直流轉換器的部分，是採用單級倍壓器，可將交流訊號做半波整流，在能量強度顯示器的部分，使用三十顆LED來做為強度顯示，全亮時總消耗電流為394 mA，因耗電量較高，故輸入驅動電壓改採用5 V，使用USB接頭當作供電介面，可用筆記型電腦或使用有USB接頭的行動電源供電。

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.

[1] A.-J. Hempy, M.-P. Civerolo, and D.-Y Arakaki, “Design and assembly of an antenna demonstration system,” IEEE Trans. Antennas Propag., vol. 54, no. 2, pp. 209-219, Apr. 2012.
[2] F. Ellinger, Radio Frequency Integrated Circuits and Technologies, Springer Verlag, 2007.
[3] B. Razavi, RF Microelectronics, Prentice Hall, 1997.
[4] K. Kurokawa, “Some basic characteristics of broadband negative resistance oscillator circuits,” Bell Syst. Tech. J., vol. 48, pp. 1937-1955, July-Aug. 1969.
[5] G. Gonzalez, Microwave Transistor Amplifiers, Analysis and Design Prentice Hall, 1996.
[6] A. Hajimiri and T. H. Lee, “Design issues in CMOS differential LC oscillators,” IEEE J. Solid-State Circuits, vol. 34, no. 5, pp. 717-724, 1999.
[7] C.-L. Chang and C.-H. Tseng, “Design of low phase-noise oscillator and voltage-controlled oscillator using microstrip trisection bandpass filter,” IEEE Microw. Wireless Compon. Lett., vol. 21, no. 11, pp. 622-624, Nov. 2011.
[8] M. Nick and A. Mortazawi, “Low phase-noise planar oscillator based on low-noise active resonator,” IEEE Trans. Microw. Theory Tech., vol. 58, no. 5, pp. 1133-1139, May 2010.
[9] J. Choi, M. Nick, and A. Mortazawi, “Low phase-noise planar oscillator employing elliptic-response bandpass filter,” IEEE Trans. Microw. Theory Tech., vol. 57, no. 8, pp. 1959-1965, Aug. 2009.
[10] M. Tsuru, K. Kawakami, K. Tajima, K. Miyamoto, M. Nakane, K. Itoh, M. Miyazaki, and Y. Isota, “A triple-tuned ultra-wideband VCO, ” IEEE Microw. Wireless Compon. Lett., vol. 21, no. 11, pp. 458-461, Nov. 2011.
[11] D. M. Pozar, Microwave Engineering, 2nd Ed., New York: Wiley, 1998.
[12] C. A. Balanis, Antenna Theory analysis and Design, John Wiley & Sons, Inc.1982.

[13] J. D. Kraus and R. J. Marhefka, Antennas: for All Applications, 3rd Ed., Mcgraw-Hill, 2003.
[14] 白光弘, 天線原理及應用, 國立編譯館, 1999.
[15] W.-H. Tu, “Microstrip-coplanar stripline-fed Yagi-Uda antenna” in Proc. IEEE
Int. AP-S Symp., San Diego, CA, pp. 1-4, Jul. 2008.
[16] J.-S. Hong and M. J. Lancaster, Microstrip filters for RF/Microwave applications. New York: Wiley, 2001.
[17] B.-T. Tan, S.-T. Chew, M.-S. Leong, and B.-L Ooi, “A dual-mode bandpass filter with enhanced capacitive perturbation,” IEEE Trans. Microw. Theory Tech., vol. 51, no. 8, Aug. 2003.
[18] T.-W. Lin, U-H. Lok, and J.-T. Kuo, "New dual-mode dual-band bandpass filter with quasi-elliptic function passbands and controllable bandwidths," IEEE MTT-S Int. Microwave Symp. Dig., pp. 576-579, May 2010.
[19] M. Makimoto and S. Yamashita, “Bandpass filters using parallel-coupled stripline stepped-impedance resonators,” IEEE Trans. Microw. Theory Tech., vol. 28, no. 12, pp. 1413-1417, Dec. 1980.
[20] 翁敏航, 射頻微波被動元件, 國家奈米元件實驗室, 95年.
[21] B. Foley, P. Murphy and A. Murphy, “ A monolithic SiGe 5 GHz low noise amplifier and tunable image-reject filter for wireless LAN applications “, High Frequency Postgraduate Student Colloquium, pp. 26-31, 2000.
[22] 袁帝文/王岳華/謝孟翰/王弘毅, 高頻通訊電路設計, 高立圖書有限公司，96 年.
[23] G. Gonzalez, Microwave Transistor Amplifier Analysis and Design, New Jersey, Prentice Hall Inc, 2nd Ed., 1996.
[24] T.-K. Nguyen, C.-H. Kim, and G.-J. Ihm, "CMOS Low-Noise Amplifier Design Optimization Techniques, " IEEE Trans. Microwave Theory Tech., vol. 52, no. 5, pp. 1433-1442, May 2004.

[25] H.-H. Hsieh and L.-H. Lu, "Design of ultra-low-voltage rf frontends with complementary current-reused architectures," IEEE Trans. Microwave Theory Techniques., vol. 55, no. 7, pp. 1445-1458, Jul. 2007.

[26] M. M. Weiner, “Analysis of Cockcroft-Walton voltage multiplier switch an arbitrary number of stages,” Review of Scientific Instruments, vol. 40, no. 2, pp. 330-333, Feb. 1969.

[27] D.-R. Jackson and N.-G. Alexopoulos, “Simple approximate formulas for input resistance, bandwidth and efficiency of a resonant rectangular patch,” IEEE Trans. Antennas Propag., vol. 39, pp. 407-410, Mar. 1991.

[28] M.-P. Robinson, T.-M. Benson, C. Christopoulos, J.-F. Dawson, M.-D. Ganley, A.-C. Marvin, S.-J. Porter, and D.-W.-P. Thomas, “Analytical formulation for the shielding effectiveness of enclosures with apertures,” IEEE Trans. Electromagn. Compat., vol. 40, pp. 240-248, Aug. 1998.