Guy...a great post! Great information for those of us who are looking for RX antenna options but don’t have the room for the normal RX antennas...
And also a real breath of fresh air in light of our recent discussions.. Thank You! Cecil K5DL Sent from my iPad > On Aug 3, 2019, at 5:17 PM, Guy Olinger K2AV <[email protected]> wrote: > > Hi, Ed, > > You're on the right track. > > A "beverage" ON the ground really is NOT a beverage. For two things to be > called the same genus, they need to have most everything in common. This is > true of big yagis, little yagis, short yagis, long yagis, trapped yagis, > linear loaded yagis, end loaded yagis, moxons, yagis at 30 feet and yagis > at 200 feet, etc. One program optimizes them all. A yagi is a yagi, is a > yagi, is a yagi, and all of them have a ton of yagi-ness held in common. > Simply not so BOG vs. beverage. > > Creating beverage advice from one particulars person's wire down close to > or on the ground at their particular property, may be simply and totally > wrong for someone else. The normal beverage tuning instructions, usually OK > for wires a foot off the ground and maybe even OK to some degree for four > inches, simply do not apply if the wire is actually laying on the ground. > > A regular beverage has a decent RX signal strength. To be truthful, a > **real** BOG needs a remote amplifier, because its output is way down from > a real beverage. Get this much straight: an actual BOG is a LOW output > antenna, period. The way to improve a BOG's signal output is add an amp > (best remote), or escape BOG-iness and lift it off the ground. > > If you model a real BOG, you find that beyond an ELECTRICAL half wave ON > THE WIRE, or two hundred something feet on 160, extending the BOG wire will > start to REVERSE the pattern. No real beverage ever does that. Just some > beverage lengths are bit better than others FOR REAL BEVERAGES. A BOG is a > single band antenna for optimums. It will hear stuff on other bands, but > forget a designed pattern like you have on a beverage for several bands, > that work WELL on several bands. > > If you are even two inches above actual ground, laying on top of grass, you > are blending the very different worlds of pure BOG and pure beverage. If > you are at two inches, you are at a poor place to advise either owners of > pure BOG's or pure beverages. The great problem is that exactly which type > you are closer to depends on the vagaries of the location-specific ground > underneath. > > These vagaries wander HUGELY ( I'm talking about an actually carefully > ****measured**** wandering HUGELY) depending on individual properties. > Based on those **measurements** it is a normal outcome that one end of the > wire could be more BOG and the other end of the same wire could be more > beverage, and even vary more depending on whether it rained in the last few > days (or weeks depending on the local and natural drainage of the soil). > > It is clear reading a lot of the posts on BOG's from the last week or two, > that a lot of users were expecting greater signal output. Don't. A REAL > *BOG* that was laid down, notched in the grass down to the actual ground > surface, to get it out of sight and safe from lawn mowers, WILL sound MUCH > better to the ear if it has an amp. Otherwise, a BOG is a LOW LEVEL RX > antenna. > > IN GENERAL, a real BOG needs an amplifier, will usually wind up somewhere > 180 to 230 feet if you want front to back, and it's great advantage is that > it can't be mowed, snagged by galloping deer, have tree branches knock it > down, be seen by unfriendly neighbors and it will do roughly as well as a > single direction K9AY, but without the AY's ugly wires above the ground, IF > it's amplified. If the feed circuitry is done correctly, a BOG will be > wonderful at reducing local noise off the sides. > > You will increase signal level significantly by getting it up an inch or > two on top of the grass, but it ain't a pure BOG anymore, the VF is > increased significantly, and then it needs more length to be optimum at two > inches. And you will still not be able to tune it smartly like a beverage > using SWR to the terminating resistor. > > BOGs are a cantankerous RX antenna. You can throw a 250' wire down on top > of the lawn and take it up after the contest. In normal (not super quiet) > settings it WILL hear a lot of signals better than the inverted L. Just > understand that is NOT a design antenna, and was not optimized, did not > have the best signal to noise of a designed-for-location BOG antenna, and > was not as good as a beverage. > > We know what the issues are, but new-comers to the BOG idea just don't know > the vagaries and how to squeeze the best out of on THEIR property. > > The category is Ground Low Velocity Factor (GLVF) antennas. DOGs, LOGs and > BOGs. If they're up in the air, even two inches, they're likely NOT GLVF. > GLVF are low output RX antennas. If you are looking for high signal output > from the antenna without an amplifier, just forget GLVF. > > Been there, done all of that. > > 73, Guy K2AV > > >> On Thu, Aug 1, 2019 at 2:57 PM Ed Sawyer <[email protected]> wrote: >> >> Isn't BOG still a beverage just with more ground coupling loss because its >> literally "on the ground"? So the typical answer on beverages seems to be >> that 4 - 10 ft above the ground is low enough to eliminate the undesired >> noise but high enough to reduce the losses from being too low to the >> ground. >> A BOG is a beverage with higher than desired losses. But if its long >> enough, pointed in the right direction, and your ground conductivity is >> accommodating, its less of a trade than the reverse of those items. >> >> >> >> I have had a few unplanned BOGs that were discovered as "on the ground" >> because of some supports falling down. I could immediately hear the >> difference, but they still worked. Would they be usable if that was my >> only >> option? Sure. Just not as good as the same wire at 6 - 8 ft. >> >> >> >> I use 650 - 1000 ft terminated beverages and they are quite amazing. My >> ground condition is lossy and I don't have much local noise to null out. >> Its pretty much all atmospheric noise. >> >> >> >> Ed N1UR >> >> _________________ >> Searchable Archives: http://www.contesting.com/_topband - Topband >> Reflector >> > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
