- Buyers Guide
Military Microwaves Supplement
Published March 1, 2006
From: Liu Shumin, MW Center CHINA
I have designed a 1.5 to 1.8 GHz low noise amplifier. When I put a lid on its cavity, the input VSWR changes to 1.3 to 1.5 GHz. Do you know why this happens?
From: Steven Chan, Northrop Grumman Space Technology
I am using Artech House's 4th printing of Stripline Circuit Design (1982) and was wondering if equation 4-8 has a typo? I would like to know if there is an errata sheet for this book?
For equation 4-7 there is a term in the numerator w/b; in equation 4-8 this term becomes w/(2*e) where e=2.718. When I typed these equations to compute the even and odd mode impedence, I got a strange answer and only by changing the 2*e term to b did I get an answer that seems more like what I was expecting. For one thing the 2*e term caused Zoo>Zoe, which is strange.
From: Yashwant Wanmode, Centre for Advanced Technology
I fully agree with your answer/suggestion to the question asked by Mark Smith of Airnet Communication. I have also made some loop type directional couplers at S-band frequencies of WR-284 waveguide. I did not find the right literature to fix the loop dimensions and hole size. Finally, I used the "Cut and Try" method. Now my question is do I have to use the loop type directional coupler for forward and reflected waves monitoring/measuring? If one loop is measuring the forward waves what should be the distance of another loop that can measure the reflected wave? Also, how do I define the directivity in case of loop type directional coupler?
How can I design a microwave horn antenna?
What is the mathematical conversion (formula) between EVM to BER?
From: Aizu Dean, Kisarazu
I have a few questions regarding milimeter-wave circuits:
From: Tri Chau, TQT
I am interested to know why a stantion transmitter video signal does not exist in 250 to 350 MHz diapason (a transmit video signal of public safety cameras to police officers 10 km distance, for example)? Has it only been viewed by microwave bands?
From: Jason Kneier, Pratt & Whitney
I am designing a balanced, air-filled stripline fixture to be used for material characterization. It will be a rather large-scale fixture compared to what one might typically associate with stripline (the "b" dimension may be close to 3"). I am seeking advice on whether to use a broadwall or end launch at the coaxial junction. In your book, Stripline Circuit Design, I see you recommend that a broadwall launch not be used over 4 GHz, which should not be a problem for my design. Could you tell me if one of these launch methods has inherently lower return loss, or lower loss over a wider bandwidth, than the other?
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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