Published September 19, 2006
From: Chong Yik Lam, Agilent Technologies
Dear Yik Lam,
When a mismatch occurs in a transmission line, it sets up a standing wave. The peak voltage becomes 1+p and the minimum voltage is 1-p. The VSWR is then (1+p)/(1-p) and the forward loss (in dB) is 10 log(1-p^2).
From: Tamer Abuelfadl, Cairo University
I'm sorry, but we do not recommend specific manufacturers. You don't say whether your lab is for testing or actual manufacturing. If it is testing, then any of the major test equipment companies will be happy to help you. If you are fabricating, then you will need to look for either etching or profiling machines. There are several companies that make machines for prototyping purposes. They advertise in Microwave Journal. Keep in mind that there are environmental problems associated with chemical etching.
From: Mohammed Rahman, RFS
I am not familiar with the spec or its interpretation. I suggest that you contact the people who wrote it at AISG and ask them what they mean.
From: Abdul Maalik, SUPARCO
Depending on the specs at Ku-band the DRO will probably work. The paper that you reference is too old to be available on-line. If you will provide us with your mailing address, we will send you a hard copy.
From: Mehdi Karimiyan, Iran University of Science and Technology
All of the filter types that you mention are covered in Microwave Filters, Impedance-matching Networks and Coupling Structures, Matthaei, Young & Jones, Artech House Inc., 1980, ISBN#0-89006-099. There are no texts that describe design using various commercial software programs. Your best source of information will be the user manuals for each product.
From: Long Zhenjie
The subject of synthesizers and PLLs has too many variables for me to give you any definitive answers in this column. I can direct you to two excellent books on the subject, which should be helpful. They are Digital Techniques in Frequency Synthesis, Bar-Giora Goldberg, McGraw-Hill, 1996, ISBN#0-07-024166-X and Phaselock Techniques, Third Edition, Floyd Gardner, Wiley, 2005, ISBN#13 978-0-471-43063-6.
From: Shayan Jafari, Capra
For a .01 dB ripple filter, you will need four sections to get the required skirt attenuation. The real problem, however, is that in order to get a reasonable in-band loss (~1 dB) you will need a structure with an unloaded Q of about 10,000. There are no planar structures that will do this. You will have to use cavities, which are large and expensive. I suggest that you have a look at Microwave Filters, Impedance-matching Networks and Coupling Structures, Matthaei, Young & Jones, Artech House Inc., 1980, ISBN#0-89006-099-1.
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.