self made cross dipole for 137 mhz

the idea is from  Daniel Moeller, DL3RTL

this copy of picture and information has permission from Daniel Moeller, DL3RTL

seen at  http://www.fading.de/wettersatelliten.php

this is the circuit for the right-hand circular polarization antenna

schaltplan_kreuzdipol.gif

A till D, 510 mm

E coax cable 50 ohm, 361 mm

F coax cable 75 ohm, 361 mm

2 times, parallel

G 50 ohm antenna cable

and this is the temporarily mounted antenna at my solar collectors

antenne_137_800.jpg

as you see, this is only made until the next rain, when corrosion will separate connections and soldering points.

this is the swr after some tuning steps. i reduced the total length over 2 dipole elements to 102 cm. the elements itself are abt 506 mm. marker 1 is the center of 137,5 mhz. the swr minimum is still at 118,4 mhz however. to enlarge, click in the picture. marker 2 is 137 mhz and marker 3 is 138 mhz. 

kreuzdipol_50_160.jpg

picture made with fa-nwt01 

8/2009


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