16:1 Baluns/Ununs

End Fed OCF Antennas

Off Center Fed (OCF) antennas are very convenient as they will allow multiple bands of operation with a simple wire antenna which is fed off center. For example, the Palomar Engineers 4010 OCF is a very popular antenna and consists of an off center fed dipole with sides of 55 feet and 11 feet and it will work all bands from 40-6 meters.The End Fed OCF uses the same dimensions but the wire section is 55 feet as in the OCF and the coax outer braid is used for the “other” short side of the OCF dipole. We place a choke on the coax at the 12 foot distance from the matching unit and we essentially have an OCF antenna with its great frequency range, but with only a 55 foot wire length instead of the 66 feet required by the regular OCF. You feed the antenna from one end which may be more convenient for some installations. This antenna will work on 40-30-20-17-15-12-10 and 6 meters. Most bands are under 3:1 SWR and easily tuned by your transceiver’s internal antenna tuner or external tuner used with an amplifier. (see BULLET-4006 for specific details and SWR curves).

These antennas are MUCH BETTER PERFORMERS than End Fed Half Wave antennas because they work the WARC bands, DO NOT HAVE A DANGEROUS HIGH VOLTAGE at the antenna connection and are SHORTER to fit in smaller spaces yet provide more band coverage up to 6 meters!

16:1 Baluns are useful between 750-850 ohm balanced loads where the impedance at the  end of the feed line is 800 ohms (1/2 wavelength feed line), or high impedance feeds for rhombic,  T2FD and traveling wave antennas.

16:1 Ununs are useful between coax and long wires with a load impedance near 800 ohms like a beverage antenna.  Shortwave listener antennas also can benefit with the 16:1 unun and it may provide a better match than 9:1 ununs – this means quieter noise levels and stronger signals so you can hear distance stations easier.