8-Element 432 MHz Quagi

By Paul Bock, K4MSG of Hamilton, Virginia
Monday, September 13, 2004 8:51 AM

Click here for other articles by Paul posted to the LARG Internet Site

          Last week, I threw together a 8-element Quagi for use in the September VHF QSO Party. The antenna worked pretty well. There wasn't time to put it outdoors on the mast so it was mounted in the upstairs hallway adjacent to the shack, about 18' above the ground and surrounded by house wiring, ductwork, etc. The antenna has a wood boom and six 1/8" aluminum rod directors. The driven element & reflector are made from #12 insulated electrical wire removed from a length of Romex and are held in place by Lucite strips mounted on the wood boom. I used a Type N chassis mount female connector. The coax in the photo is Belden 8214 foam-type RG-8/U but I recommend something having lower loss for any run longer than 25 feet.

Photo by Paul Bock - K4MSG

           Running 20 watts on 432 SSB I was able to work as far away as FM17 - Henry, N4HB, in Richmond, VA and I heard some other stations that I could not work due to the low power. Had the antenna been outside on the mast I would have done much better on 432. This antenna, if carefully built and mounted in the clear, has been measured at between 12 & 13 dBd - that's dBd, *NOT* dBi - at various antenna measuring contests. If you have to buy everything to build it the cost should be less than $20 not counting the coax.

          The contest was fun, picked up 5 new grids on 6 meters; the Par SM-50 Moxon antenna on 6 meters worked very well. Unfortunately, my Mirage 2-meter amp died the night before the contest and I had to disconnect it and run the 706MkIIG barefoot; the difference on transmit was only 3 dB - 50w versus 100w. But, I missed the preamp in the Mirage.

           This antenna is based directly on the designs by Wayne Overbeck, N6NB - formerly K6YNB, as designed in the early '70s and published in QST in 1977, with a follow-up article published in 1978 on a 15-element Quagi for 432 MHz. A recent article by Wayne that incorporates all the dimensions for the original 8-element design, plus the 15-element 432 MHz design, and dimensions for 10 and 15-element 1296 Quagis, can be found on the Internet Click Here . Quagi dimensions are given in the above article for 8-element versions for 144.5, 147, 222, 432, and 446 MHz.

           I've been working with Pete Mazzerelli at Gulf Alpha Antennas on a new design of a 8-element wide-spaced Yagi for 432 MHz based on Pete's current 440 design. I'll be the first one to try out this new design and I'm anxious to compare it with the Quagi and see how an $85, computer-modeled all-aluminum Yagi compares with the super cheap, wood-and-wire Quagi.

           73, Paul, K4MSG