I thank Mr. Polivka for reading my paper ("Reader Feedback," June, p. 13). Yet I'm concerned that Mr. Polivka does not understand the arrangement of my rectenna (Fig. 1). I'm not sure why he is talking about single phase and efficiency of 50 percent. In this paper, we have done new research and it is not a copy of ref. 14. It should be noted that refs. 7 and 15 provide an RF conversion efficiency of about 82 percent at an input power level of 50 mW. We have improved the design of all components including tuning stubs to receive the conversion efficiency of 88 percent.
This is a receiving and rectifying rectenna, which efficiently converts microwave power into DC power. This rectenna has nothing to do with the propagation loss.
I request that Mr. Polivka study reports from NASA and JAXA before passing comments on those engineers and scientists from NASA and JAXA. In those reports, NASA and JAXA have taken into account the huge propagation loss. Dr. Shinohara of Japan has written in his recent report that "the Solar Power Satellite is expected to realize around 2030."
Dr. A. Kuma
Point Of Clarification
Dear Mr. Browne,
In the May 2010 issue of "Microwaves & RF" magazine, there's an error in the article,"Precision Cables: Preserve Microwave Measurement Accuracy," by Ashok Bindra, where in the table in the lower left side corner of page "S2," the attenuation in dB/ft. at 18 GHz is listed for the Sucoflex 404 as 0.984 dB/ft., whereas the correct units for that value is dB/meter (which works out to about 0.3 dB/foot). That's quite a bit off, so I thought I should point it out.
Also, the article says that Huber+Suhner is Swiss in one part, which is correct, and then later says "the German maker," which is incorrect.
I've bought these cables (along with others listed in the article), and think they're very good.
This article covers an important topic, and there are many solutions. It's good that your magazine spent some time on it. Given the wide variety of product offerings available in the industry, however, I wonder if it would be best to organize the article so that the cables are segmented by something such as frequency range, using at least a couple frequency ranges (for example, separating those cables that can work without moding above 40 GHz vs. those that don't).
Matthew Isaacs Senior Manager,
Network Infrastructure Group