Thanks for the comments, Ralph, Most of us OT's have known about the cross polarization for decades. But it really does hit home when you try it out for yourself. I had never had both horizontal and vertical antennas available to me at one time as I only had horizontal back in 1964 when I was first on 2 meter AM. Later on I only had vertical.
I spent some time searching the web for some solid information on the distance issue. Some practical numbers perhaps? There just does not seem to be that much advantage to horizontal the closer the stations are to each other. Some difference on the over 100 mile paths perhaps, but I wonder how often we will use that long a path on VHF for this kind of work. My recent SSB contact to north of Chicago to a high end weak signal operator to my 50 watts with a 4 element beam at a very good location tells me that this 180 mile path might have even been difficult for digital modes. Lots of very warbly audio and severe QSB making phone contact barely possible. But it would have been most interesting to try digital on that path to get a feel for it. For digital modes I can operate 160 meters up thru 6 meters, but not 2 meters at this time. Perhaps some of you have tried calling CQ on PSK31 or other modes on say, 6 meters? I have done this many times on 50.290, but no luck and have never heard anything either. I have heard some PSK31 on 28.120 but nothing "local" as it was likely all Es. Using repeaters is absolutely not an option since we are specifically trying to operate without infrastructure and if the repeaters are operational, other communications are likely to be operational as well in an emergency situation that we are preparing for. And with our terrain, 20 miles on VHF FM through a repeater, can be difficult. Our repeater drops out in several directions when you approach that point when operating mobile, even though the repeater location is on a high water tower at about the highest point in the county. We will find out a lot more this spring/summer when we do the 2 meter SSB tests and find out for myself. Maybe I can convince someone to operate VHF digital? We hope to do something with 6 meters too, but Skip recommends 2 meter SSB equipment for NBEMS digital. We will also be trying several HF antennas to compare portable operation. We have mobile HF operation with my wife's vehicle, but you lose ground wave on 75 meters within 10 to 15 miles. Since there is minimal NVIS pattern from a vertical HF antenna, mobile operation does have its downsides for close in work. Much of what hams think is "ground wave" on HF, can be NVIS. If the FoF2 drops down to 2 MHz at night, I have found it impossible to try and communicate on 80 meters with a station only 20 miles away. And that is using CW! To give you an idea of the problem that an ARES ham faced this summer during the 1000 year flood, he was stationed at a remote location that was well out of range of the repeater. I just measured the distance and it is only like 15 to 18 miles and yet he had no way to hit the repeater from that location, even though he had a very good portable setup. The only way he could contact the DEC to coordinate ARESMAT help was with cellphone. He later admitted that this was a ridiculous situation. I pointed out that if he is serious about an amateur radio solution, he, and others in ARES/RACES, really need to give consideration to getting their General class license and having HF capability and have the equipment and know how to use it. The only other possibility that I can think of is 2 meter SSB phone/digital, but as I have said, no one has tested the efficacy as yet. In terms of the EOC, we have had several Field Day activities at the site and we tried to set up an 80 meter dipole but the building really does not fit that kind of antenna very well and is festooned with many other antennas that we don't want to interfere with. So if we absolutely must set up HF at that location, we can quickly install a sloper dipole. Not pretty as you point out, but will work. An alternative would be to have a VHF ink to a home station that has emergency power. Or both as needed. 73, Rick, KV9U Ralph Mowery wrote: > YOu are finding out what others have known for years. > There is around a 20 db differance in cross > polarization. > > MOst hams that are serious on ssb on vhf and above > will be using horizontal for several reasons. It > seems to give slightly more distance and the mast > going to the boom is not in the antenna patern. > > Also 20 miles is nothing to vhf ssb. It seems many of > the weak signal ssb stations are not too interisted in > emergency service. Unless you have unusual > requirements, vertical antennas for short distances on > FM, and use repeaters. For longer distances just drop > the the low bands. > > I have seen posts as to where the emergency building > owners do not want to have their building's beauty > messed up by ugly antennas. When that hapens, I would > be tempted to remind them of New Orleans an just pack > up and leave them. > > > > > ____________________________________________________________________________________ > Be a better friend, newshound, and > know-it-all with Yahoo! Mobile. Try it now. > http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ > > > > Announce your digital presence via our Interactive Sked Page at > http://www.obriensweb.com/sked > > Check our other Yahoo Groups.... > http://groups.yahoo.com/group/dxlist/ > http://groups.yahoo.com/group/contesting > http://groups.yahoo.com/group/themixwgroup > > Yahoo! Groups Links > > > > > > >
