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Published May 3, 2006
From: Hasan Ajam, Faramoj
I have a question regarding quality factor of varactor diodes at different frequencies. In the data sheet of varactor diodes the quality factor is determined only at one frequency. What is their quality factor at other frequencies?
From: David Wang, AFEU
The program I am involved in now needs a delay circuit that can achieve 20 to 40 nanoseconds delay for transient signals (impulse trains) up to several GHz (subnanosecond pulse width). Are there solutions that can meet these needs while remaining compact and small in waveform distortion? The area for the delay circuit in the program is very limited.
From: Bharatkumar Mehta, Space Applications Centre
What are the different ways to measure AM to PM transfer co-efficient in TWT amplifiers?
From: Robert Badzey, Boston University
I have a question about RF MEMS and their impact on the wireless market. Literature I have read implies that two of the big advantages of RF MEMS are size and power savings. Size/integration is obvious. It is the second point, however, that has me confused. How will the replacement of a passive SAW filter with a MEMS component affect the power consumption? Again, the literature I have read implies that because of the high-Q of MEMS filters, it is possible to reduce the dynamic range of the LNA (and possibly the transmit PA) and therefore its power consumption. Just how much of a savings would that yield? What is the relationship between the LNA's power draw and its dynamic range? I am not in the RF engineering field (I have a degree in physics), but am curious as to what concrete savings such advancements might bring.
From: Mohammad Reza Modarresi, Sharif University of Technology
I want to design and implement a low phase noise microwave oscillator. I would like to know if there is an on-line article that has done a complete literature review on this subject.
From: Justin May, Stanford Linear Accelerator Center
I have been trying to develop a 20 dB coupler, either microstrip or stripline, for beam position monitoring equipment at ~6.5 GHz. I need as directive a coupler as possible (10 to 20 dB), as the coupled signal is part of our calibration scheme. So far I have been trying to do an all FR4 board (budget-constrained). I have checked designs with ADS and calculation by hand. However, none of them have worked. In most cases they were non-directive, in some the directionality was in the other direction. Is this difficulty (with something that should be simple) intrinsic to the material (FR4) being used at C-band? Can I even expect to find a solution without going to a hybrid board?
From: Jeffrey Chuan, Indra Sistemas
I am trying to design filters with a suspended stripline substrate. Do you have any idea of where I can find information relating to this topic?
Harlan Howe, Jr. received his BS degree in optics from the University of Rochester in 1957. He has been actively engaged in the microwave industry for 48 years, first as a design engineer and then as an engineering manager. In 1990 he became the publisher/editor of Microwave Journal. He retired as publisher in 2001, but remains the editor. He is a Life Fellow of IEEE, past president of MTT-S and the recipient of an IEEE Third Millennium Medal in 2000 and the MTT-S Distinguished Service Award in 2005.
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