• A two meter long 80 meter dipole will be about 10% as efficient as one 40 meters long at the same height. Most texts quote dbi information for a full sized dipole 100 feet high. If you put your antenna near the ground it may not be much more than 1% as efficient as the full sized antenna at 100 feet.
• By the way, K7MEM's site tells you what the minimum size is that you want to go for efficiency, for whatever short dipole you build. If memory serves, it was about 12.4 to 13 meters (I forget which), or 40 to 41 feet, for a 40m dipole with coils..
• I set to work to scale the antenna from its original size up to a length that would work for at least part of the 6 meter band. After much tapping on the calculator I decided to use 67" for the upper element and 46 1/2" for the lower element with a 1/2" space between them at the feed point.
• the elements and moulded dipole centre boxes, available from a number of amateur radio antenna manufacturers and at radio rallies. The dipole length should be shortened in accordance with Fig 16.1 to compensate for the larger element diameters. Construction ideas and UK sources of materials can be found at [1].
• The 40 meter dipole was loaded with some coils so that I could fit it in the attic. It gave me 40, 20 and 15 with a push because although a 40 meter dipole should give you a resonant 15 meter antenna, in this case – with the coils for 40 – it mucked the maths up and caused the ATU some trouble. On 40m, it worked a treat.
The most widely used formula to calculate the approximate overall length of wire required for a dipole is: 468 / frequency (MHz) = length of wire in feet. The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. The results are conveniently displayed in inches, centimeters, feet and meters.
(Example: for channel 2, the frequency is (6 x 2) + 45 = 57 MHz, so the wavelength on twin lead is 0.95 x 300/57 = 5.00 meters, and the antenna should be 5.00 meters/2 = 2.5 meters.) Strip the insulation off just enough of each end to be able to twist the conductors together and solder. This is the "folded dipole" antenna.
Buy two antennas per band and carry a full HF dipole system everywhere you go! You only need one DMOUNT1 as you simply swap out antennas to change bands. We can provide antennas for 6m, 10m, 12m, 15m, 20m, 30m, 40m, 60m and 75/80m. Nov 25, 2015 · Introducing the W8AMZ 80–6m OCF / Windom Multi-Band Antenna using a 4:1 Balun and rated for 2 KW. The SWR is generally below 1.5:1 on 6, 10, 20, 40 & 80m bands and can be operated without an antenna tuner. With an antenna tuner, you can operate 12, 15, 17, 30 & 60m bands with ease, where most built in antenna tuners will find it very easy to ...
An example in organic chemistry of the role of geometry in determining dipole moment is the cis and trans isomers of 1,2-dichloroethene.In the cis isomer the two polar C−Cl bonds are on the same side of the C=C double bond and the molecular dipole moment is 1.90 D.
Parallel 50 ohm lines – 45.13 ft, 75 ohm line – 7.36 ft, dipole half-length = 33.03 ft Four 50 ohm lines – 44.87 ft, 75 ohm line – 6.51 ft, dipole half-length = 32.80 ft Optimized 40m Flat Dipole at 40 ft using Two Mar 29, 2014 · Using schematic plans from the internet, I made a folded dipole antenna for 2 meters out of copper wire instead of copper tubing. I am getting rather bizzare readings from the MFJ-269 antenna analyzer, though. Here is a sample of the readings: MFJ-269 Readings Frequency / SWR / Rs / Xs 134.000 / 1.1 / 38 / 0
Dipole Antenna: A dipole antenna is the simplest type of radio antenna, consisting of a conductive wire rod that is half the length of the maximum wavelength the antenna is to generate. This wire rod is split in the middle, and the two sections are separated by an insulator. Each rod is connected to a coaxial cable at the end closest to the ... This page allows you to calculate the length for a 5/8 wave antenna. It uses the standard formula, 585/f (178.308/f for metric) MHz to calculate the element lengths. If you've experimented with 5/8 wave antennas before and know of a better formula for your QTH, feel free to change the formula to suit. This formula is for a wire antenna.