MEF-330-1K Multi-Band End Fed Half Wave Antenna Transformer
This is an End-Fed Half Wave antenna (EFHW) Transformer for frequencies between 3 and 30 MHz. To use it at any frequency in this 3-30MHz spectrum just add half wave long wire for the frequency of your interest. The benefit of the EFHW antenna is that it will be resonant on harmonically related frequencies.
- NO TUNER needed!
- NO counterpoise needed! (Grounding recommended)
- Frequency coverage:3-30MHz
- Just adding a wire radiator of ~130 feet makes this antenna resonant on 80/40/30/20/17/15/12/10m.
- Wire of ~66 feet will give you low VSWR on 40/20/15/10m
- Power Handling:1kW I.C.A.S
- Weight: 0.95 lbs. (0.43kg)
- Hardware: Stainless Steel
- Connector: Silver/Teflon SO-239
For example, 7 MHz half wavelength is 20 meters or 67 feet of wire or two half wave on 14MHz, also it is four half waves on 28MHz. So, wire for 7MHz will give you low VSWR on 14 and 28MHz, 15m or 21MHz is also related as three Half Wavelength and there you might have low VSWR too. It all depends on height over the ground and objects around the antenna. The wire length can be calculated by the following formulas:
- Length (feet)= 468/Frequency (MHz) or
- Length (meters)=142.5/Frequency (MHz)
Always cut a wire a bit longer to allow for tuning to your desired frequency. Tuning depends on height above ground and nearby objects. There are so many ways to install the wire and your imagination is only limit. You can do it horizontal, vertical, sloping, an inverted “L” shape, in “inverted “V” shape, Horizontal L, etc. Such antenna will not need radials and in most cases NO Tuner at all. Be a HAM and do some experiment. Grounding at the lug next to the SO-239 connector is recommended! Long wires tend to collect electrostatic charge (usually when weather is stormy) which can produce ESD (electrostatic discharge) at the end of your cable and damage your equipment.
The longer wire will give you more harmonic related resonances, For example, Half Wave wire for 80m or 3.5MHz will give you (8) eight resonances up to 30MHz. See this picture of low VSWR resonances taken with 130Feet (39m) of wire at only 20 feet (6 meters) above ground.
It starts from 6 feet (1.8m) at the transformer, and then it goes over the tree branch at about 20 feet (6m) and ending at only 10 feet above the ground. Also, see the response of VSWR per band in other images, note that antenna is very low for 80m band and your VSWR curve might be a bit different at your location. Always aim to put the wire higher and leave the wire a bit longer at the end in order to tune it at the desired frequency.
Shorter versions of antenna utilizing TRAPS and Resonators will be available soon.
Subscribe to our Newsletter on the bottom of this page to get more information about this and other antennas. Antennas are in production and first models out of many are coming soon. Stay tuned…. 73 Danny Horvat, E73M/N4EXA (former Cushcraft Corporation antenna designer)
Gallery of VSWR images per band with 130 feet (39m) long wire at only 20 feet above the ground.