We designed the 5/8 antenna in 1996 and since then we have sold more than 1000 of them worldwide. We can count the number of returns on less fingers than you have on one hand. This really is a high-performance antenna in every form. Fantastic RF gain, physical strength and durability, high power handling and easy installation. It will work in rain and moderate snow, but it's like a car, it will not work if it is completely submerged in snow and ice. We have customers that are still using this antenna after 15 years of little or no maintenance. It is precisely tuned to the operating frequency of your choice and provides your transmitter with a perfect match and a gain of around 4.8dB, increasing your effective radiated power by about 2.8 times.
With correct mounting the RF field strength directly below this antenna is much lower than a dipole. The truly unbalanced input prevents any RF currents traveling down the outer of the feeder cable. This combined with the low field strength below the antenna and tight bandwidth reduces the chances of audio, TV and other interference considerably and maximizes RF power to the horizon.
Below is the radiation pattern for our 5/8 antenna showing a cross section of the signal between the antenna and the horizon at 0 and 180 degrees. Looking down from above at the 0 degree point the radiation pattern is perfectly circular.
The antenna is constructed from aluminum with UHMW PE insulators. UHMW PE (Ultra High Molecular Weight Polyethylene) like Teflon has an incredible dielectric strength of 28kV/mm, but with the additional advantage of being 5 times stronger than Teflon, so it's the better choice for high winds. Coaxial line losses can be considerable at 88-108MHz. For long runs use a good quality cable such as LMR400 or equivalent for connecting the antenna to the transmitter. Total length 2 meters.
There are no traditional coils or capacitors in this design. The square piece at the bottom and the tuning bars are the coil and capacitor transforming the unbalanced feed from 50 ohms up to around 1000 ohms. Since it uses big lumps on aluminum in its construction nothing gets hot, not even with 2kW. The main insulator is Teflon, so that doesn't even feel the RF signal or get hot. This antenna handles 2kW with ease, in fact probably 3kW only limited by the 7-16 DIN connector, not the rest of the antenna.
Gain (Isotropic) | +4.8 dBi |
Frequency Range | 87 - 109 MHz |
Bandwidth | +/-2 MHz 1.5 VSWR |
Construction | UHMW PE/Aluminum |
RF Connectors | N type / DIN 7-16 |
Impedance | 50 ohm unbalanced |
Polarization | Vertical |
Maximum RF Power | 1kW / 2kW |
Weight of Antenna | 1.8Kg |
Wind Speed Handling | 90 MPH |