Sunday, October 12, 2014

160 Meter Antenna Now Up

My 160 meter antenna is just my modified inverted L that I used mainly for 30 and 80m.  It is largely based on the antenna design published by NU8Z.  All I did to it is added an extension of 15 feet to an otherwise 70 foot quarter wave inverted L.  The key to this extension is a piece of 2 inch PVC pipe wrapped with 156 turns of  tightly wound 14 gage insulated wire giving me about 119 mH of inductance.  This coil acts as a trap for frequencies below 80m.  The coil acts as a shortened 1/4 wave vertical on 160m.  A full size quarter wave on 160m is 40m long or roughly 134 feet.  The shortened vertical is about 85 feet long with the coil between the 70 foot and 15 foot extension.  It really works - the resulting SWR pattern is as shown below.

It rather narrow banded with about 50 kHz around the center frequency that is below 2:1 SWR.  The dip at 1820kHz.

It uses the same radial field as shown below.

On air results are QSOs with stations in the PA QSO party, W1AW/4 portable and friends N4IQ and N0TR.

It probably could be more efficient.  My input impedance is right at 52 ohms indicating that I need more radials.  On 80m it is efficient enough to have gotten me close to DXCC - 95 confirmed. 

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