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From: geraldj@ames.net
Subject: Laport rhombic
Date: Sun, 01 Dec 1996 12:13:14 -0600
I stumbled on the latest edition of Jasik on my way to bed last night and looked up rhombics. The chapter was written by Laport and he reports that his double rhombic design gives a cleaner pattern with smaller side lobes than the standard single rhombics. The reference is to an article in RCA Review in March 1960. E.A. Laport and A.D. Veldhuis, "Improved Antennas of the Rhombic Class," RCA Rev., March 1960. I plan to be at a library that has RCA Rev sometime in the next week, so might look up the article.

The last time I looked at wire antennas compared to rhombics at 2m I concluded that gain was achieved far easier with NBS yagis than with a cats cradle of wire and in far less space. With a 50 foot wide flat roof available on a multi story building there was more gain available from a yagi with 20 foot boom and a single mast than stacked rhombics using the whole roof and multiple masts.

I also dug up the QST picture. 17.1 dbi is not much gain for an 8 foot boom. I have a 27 element SI loop yagi that did that (as I recall) with a 6 foot boom at a previous CSVHF conference. The 44 element KLM did more like 17.5 dbd (e.g. 19.9+ dbi) a few years ago. Its not really all that big... Unless I can find metric aluminum to build a copy of the really long DL6WU 1296 yagi, that KLM looks like what I will put up in the future.

73, K0CQ

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