ZL1RS - Antennas

This 10 element LPY was built to overcome a problem that occurs with most 6m Yagis when used as a "scanner antenna" while looking for propagation indicators below 47MHz. The radiation pattern of most 6m Yagis flips below 47Mhz showing more gain "off the back". It is not very convenient to rotate the 6m Yagi 180 degrees to look for propagation indicators, then back again to call stations on the 6m band. It is also easy to be confused about which direction an indicator is coming from.

This VHF LPY was designed from an old DOS LPY calculator that was distributed with the ARRL Antenna Handbook software in the 1990's. There may be on-line LPY calculators available these days that would do a better job?

The LPY is built on a 5.3m long 1" square boom using mounting insulators from the TV industry. A short mid-boom stiffener is used to allow the boom to mast clamp to be mounted lower so the mast does not contact the phasing line. The LPY is fed with 50ohm coaxial cable via a 4:1 balun.

I built this LPY from materials on hand but a simpler approach may be to buy a low band LPY style TV antenna. However, these will become harder to find as the introduction of Digital TV means all ZL TV channels will change to UHF and Ku band satellite by 2013.

Update: August 2012. This antenna has been dismantled.



LPY Forward Gain and F/B curves from 36 to 56Mhz



Radiation pattern at 42Mhz



SWR at 42Mhz



Radiation pattern at 52Mhz



SWR at 52Mhz