Rick, I have change the topic to more appropriately describe what is being discussed.
> Judy and I did further testing of 1/4 wave and 5/8 wave antennas for 2 > meters on her vehicle using the ICOM IC-7000 at 50 watts out. The base > station continued to be the 30 foot high homebrew J-pole and now has 100 > watts out from the ICOM 746 Pro. The mobile antennas were only mag > mounts, but then again, that is what most of us use. > > The furthest point out was 40 miles and we could still communicate on 2 > meter SSB, but signals were quite weak. When she was mobile, there were > locations that were so weak as to be unreadable at times. Some of those > areas are difficult to even work the local FM repeater which is about > 200 feet higher than our home QTH antenna and about 6 miles closer than > our QTH! First, thanks for making the tests! The question is whether or not the shadow of hills resulted in the reduced range on SSB, since in flat country, we can get over 70 miles on FM with DominoEx or over 100 miles on SSB with DominoEx. I am somewhat familiar with the Wisconsin countryside as I used to visit Monroe, Madison, Blue Mounds, and the Dells several times a year - beautiful, rolling, hills. My ancestry is Norwegian and I especially enjoyed visiting during the Pier Gynt festival every year. > > There were slight differences between the 5/8 wave and 1/4 wave. > Sometimes the quarter wave would out perform the 5/8, but in general, > the 5/8 did slightly better, especially farther out. Because of the > convenience of the quarter wave (entering the garage), it is hard to > beat, but I would like to try a half wave Larsen some time. People use the 5/8 wave antenna for increased gain, but mainly because it lowers the takeoff angle from 45 degrees for the ground plane to about 25 degrees for the 5/8 wave. Note that a horizontally-polarized low antenna has a takeoff angle of around 9 degrees in comparison. > > If I had been using even my modest 4 element Arrow beam, signals would > have been quite good at all times, based upon the nearly unity gain > verticals. I still need to come up with even rudimentary horizontal > dipoles at each end and see how well they compare. Just flip the Arrow beam 90 degrees, but use it on the higher fixed station end, and compare it to a small quad, which can be built in about an hour. http://home.comcast.net/~hteller/OptimizedQuad.zip > Now on the KU4AB squalo antennas, this is one of the only halo types > that does not seem to have water ingress detuning issues. Even the M > Squared products got low ratings on eham because of this problem. The > KU4AB design is the one that got the good numbers on the Central States > VHF Society test. They did not mention that there were any anomalies in > the omnidirectional pattern, but your experience sounds unacceptable! > > According to the M Squared advertising on the 144HO loop, they claim as > you do that only horizontal type antennas can give you the ground > reflection gain. Their numbers and shape of the antenna look very much > like the KU4AB. I wonder why so many are going with the squalo shape > over what would seem to be a stronger shape when in a circle? Even the halo is not perfectly omnidirectional. To get that, you need to turnstile dipoles (or rectangles, or skeleton-slots). I never noticed that on the M Squared site, but it is significant that the company considered to be the premium supplier of yagi's by the weak signal community also finds that horizontal polarization has more gain than using vertical polarization, especially at low heights (and so does the modeling). > > Can you recommend any current manufacturer for circular halos? The other > well known manufacturer has been SK for some time and no one was > interested in taking over the business. I think all the halo manufacturers are gone since horizontally polarized mobile antennas generally went the way of the dinosaur with the spread of repeaters. > > Maybe build my own? A single halo may not be too bad, but I don't know > if I can do a good job with phasing lines. And those gamma matches are a > challenge. > > What are stretched quad loops? Can't seem to find anything on them. Or > is that the optimized quad, but not intended for mobile operation, more > for portable? Avoid matching problems by using turnstiled loops. Here is my prime reference on stretched loops: http://personal.ee.surrey.ac.uk/Personal/D.Jefferies/antennexarticles/behave.htm There is really no good new commerical omnidirectional antenna for 2m, but right after the Shelby, NC, hamfest, I worked K4LY on SSB phone in his driveway, 200 miles away, to a squalo mounted on his Prius. I had him drive in a circle so I could see the pattern, and there were the expected nulls. Signals were marginal, but he lives on a 200 feet hill next to a cell phone tower, and my 13B2 is in my attic at only 25 feet. Did not have a chance to try it using DominoEx, though, but I suspect print would have been very good. We will be doing long range tests together on FM using DominoEX in the next few weeks, and I'll report the results here. I have repeatedly worked WO4DX, as he travels on business from my qth town in Mount Pleasant to his home in Dawsonville, GA, with my 13B2 when he was using stacked halos on his mobile. Signals always hold up for about 90 miles from me and then they become too weak to copy on SSB phone. Of course, typing while driving is not recommended, so for mobile operation while moving, phone is used most often. If you have to stop to type using digital modes, you might as well just plop the OptimizedQuad on a magmount on the roof and turn it toward the station or desired direction instead of being limited by the range of a halo. You can probably exceed the SSB phone range using DominoEx plus FM, but we have not yet made that comparison to get a hard number at long distances. I hope to be able to arrange that in the next couple of weeks. What slows down getting tests done is that phone is currently the convention for 2m weak signal work, so you need to add a computer, interface, and software to work digital modes. However, I am hoping I will soon confirm that FM plus DominoEX will go as far as SSB plus phone does, but using horizontally-polarized, gain antennas. Tests locally here so far indicate a 3-6 dB disadvantage using digital FM over digital SSB, but consistently an advantage over SSB phone. What I do is just turn my beam away from a station at 30 miles and reduce power to simulate a distant station, but that does not include any QSB over a longer path. We just know for sure, and have already confirmed this, that 100 miles using DominoEx and SSB with 10 dBi antennas on each end, is always possible in flat country. We now just need to confirm the range using FM. > > The Cebik antenna was in March 2008 QST entitled, "A New Spin on the Big > Wheel." While the three dipole design could be homebrewed, a well made > more wheel like design would be needed to operate mobile due to his HPOD > triangle probably not handling vibration and wind as well. I like the > easy matching approach taken. The article has some background > information I have not seen elsewhere. He considers the gain to be about > 7.2 dBi at 20 feet height, and with very accurate omni characteristics. We built one of Cebik's dipole "Big Wheels", compared it on our 2m SSB digital net several times, as well as on my beacon (8 miles away) that I use for an antenna range, and a turnstiled skeleton slot ourperformed it by 1-2 dB. I call my turnstiled skeleton slot design the "Jolly Roger" http://home.comcast.net/~hteller/JollyRoger.zip because it reminds me of the skull and "crossbones" pirate flag, with its "crossed" PVC construction. There are five of these omnidirectional antennas in use on our 2m digital SSB net, and would probably be the best antenna to use for an EOC that has a high location or tower, since it can hear from any direction. In this case, the additional gain needed to go the distance must made up by the portable station by using a 2, 3 or 4 element quad, and pointing at the EOC or net control station. The way we run our 2m digital net is have all stations beam (mostly with gain antennas) toward the net control station (which is using an omnidirectional antenna of low gain), and then the net control station simple retransmits (by cut and paste) all incoming text for everyone to read in case they cannot copy some other station. This is not possible using phone, but using DominoEx, the retransmission is very fast (70 or 100 wpm) compared to the average typing speed of the net member, which may be around 20 wpm. This way, nobody gets left out, and there is a minimum of dead air time compared to the typical weak signal VHF net. This works well, and we have been doing it this way for over two years now, twice a week. 73, Skip KH6TY NBEMS Development Team
