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![]() Jeff wrote: I guess I'm missing it, but what problem is there running the feedline to the normal center fed yagi? No matter if against a mast, or mounted on a mast with the center of the boom attached to the mast, I don't see a problem. I do it all the time. No matter what polarization, I tape the coax to the mast, and then tape it to the boom to the feedpoint. I'd much rather run the yagi in the normal manner. This is a problem that is particular to vertically polarized yagis that are mounted with a pole going between the elements. The pole has to come up parallel to the elements to the boom. Some people overcome this by using non-conductive pole, BUT what do you do with the feeder, if you tape it to the pole you might just as well have used a metal pole!!! However, as I said in my previous post, my simulations seem to show that with careful positioning the effects can to quite small 73 Jeff I think normally the effect is fairly small. But I suppose it can vary per the position, and mast length, etc.. I guess it's all how picky you are about the gain/pattern. For moonbounce, etc, it might be worth worrying about. But for just a general purpose FM beam, I probably wouldn't worry too much. Unless the mast was a certain length to become resonant, it should pretty much be ignored by the antenna for the most part. Seems to me, right in the middle of the two midpoint elements would be about best, but I've never modeled other positions. I have seen quite a few people run vertical yagis with the midpoint mast mount with no serious problems. I think any small loss of performance would be less than trying to voltage feed thats for sure. You'll see lots of antenna ad's with pictures of vertical beams mounted on masts in that manner, so it shouldn't be too bad. I agree. There should be little difference in using a metal mast, or plastic, if the feedline shield is in place on both. I'd just as soon use the metal mast I think. It would look fatter with the extra metal mast, but I don't know if that would be a plus or a minus... MK |
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