G8OO USEFUL INFORMATION 22/11/2018 


A very usefull Dipole Calculator by the Fists Club (Click Here) 
MORE USEFUL INFORMATION ByAUTHOR: STEVE NICHOLS G0KYA  THURSDAY 29 JANUARY 2009 


Multiband loftmounted dipoles for 40, 20, 17, 15, and 10m
Amateurs are always after the Holy Grail  an antenna that will work on all bands, is inconspicuous, effective, but above all inexpensive. Unfortunately, you seldom find something that fits all these factors. This antenna has nothing new about its design, but it does bring together quite a few useful ideas and characteristics. These are: Fully notune antenna system for five popular HF bands Suitable for SWLS, QRP, M3 licensees and PSK31 operating plus occasional use up to 100W, but watch out for RFI at high powers. DO NOT USE A LINEAR! Uses noninductive (zigzag) loading for 40m Steve Nichols G0KYA 
MORE USEFUL INVERTED DIPOLE INFORMATION BY, AUTHOR: FREDERICK R. VOBBE, W8HDU, JANUARY 4, 2008 

A half wave dipole in free space has a length calculated by 468 being divided by the frequency in megahertz (MHz). So let's suppose we are calculating for 7.1 megahertz, take 468, and divide it by 7.1, and you get 65.915492. Ok. I think we can round that to 66 feet. BUT WAIT. That's the ideal length. 468 ÷ 7.100 = 65.915 say 66ft ÷ 2 = 32.95 say 33ft each leg Add a about 6 inches to each end of the wire, then you can "tune" the antenna dead on the frequency by trimming back the wire as needed. In my 40+ years of playing with an antenna like this I have yet to calculate one that has matched on the first try. I always find that I have to add or subtract about 4 inches from the calculated length, so make your wires long, then fold them back to where they need to be.  The inverted dipole is a very popular antenna. It's also known as an Inverted "V" antenna. The inverted antenna is a horizontal dipole with the ends tilted down to the ground. The angle between the two legs us usually between 90 and 120 degrees. A typical horizontal dipole for 40 meters would look like this;
Due to the effects of the elements against each other, as well as ground, it's always been a practice to shorten the length of each wire by 36 inches. (More for lower frequencies than higher). In our example we can see that each 1/4 wavelength wire in our horizontal dipole is 32.9' long. But when designing it as an inverted dipole, on 7.100 megahertz, it was necessary to shorten it by 3".

G8OO USEFUL INFORMATION 22/11/2018 

