Sunday, February 4, 2018

Commercial versus homemade open line

Previously I wrote about the inverted-V I mounted in the mast as emergency antenna. Since the PACC contest is coming up I wanted to upgrade a little and made myself a more solid open line. The commercial brand I used was 450 Ohm JSC #13AWG open line, I think it is good quality but I connected about 3 or 4 pieces together to get the length I need. The inverted-V was also made from some pieces of wire which were leftovers from another antenna project. Now for this inverted-V I also use 2,5mm2 (#13AWG) but this time there are no connections. The whole antenne is made from 2 pieces of 50m wire. Spreaders for the open line are plastic fruitclips. Unfortunately I could not see any signal increase at receiving compared to the old inverted-V but I think the difference will be the weather impact on the open line and antenna. How it radiates in not certain yet? Have to test it first. The only thing that is different are the tuner settings due to a different impedance. Hopefully it will be good for the PACC next weekend. I'm not really satisfied with this antenna, it has to proof itself first. Compared to my 84m long horizontal loop I used in the previous years I can't say it's good. Compared to my homemade multiband vertical it's about the same on 60-10m and a little better on 80m. I can use it on 160m but the vertical is far better. The horizontal loop couldn't be tuned on 160m but was better compared to my vertical from 80-15m. It's nice to have a comparisation antenna so you can see what a new antenna is doing. Next step will be the moving the vertical from the old mast (9m asl) to the new tower (16m asl). The problem is it is impossible ( impractical)  to attach radials below the vertical. Using the mast as counterpoise is an idea but it will have a strange impact on the radiation pattern at the higher bands. Have to study what the best option is.

4 comments:

  1. Hallo Bas,
    Ik denk dat met de mast als counterpoise je een meer lagere afstraling krijgt dan met de radialen wat met de vertical werkt als een groundplane. Zoals je weet heeft een 1/4golf groundplane een hogere opstralingshoek. Lees het boek maar eens wat ondderweg naar je toe is. Succes. 73v Hans, PE1BVQ

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    1. Op de lage banden 160/80 en in lichte mate op 60m wel Hans. Maar hoger dan 7 MHz is de mast te lang en krijg je juist een hoge opstralingshoek. Heb dit met EZNEC en 4NEC2 gesimuleerd. 73, Bas

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  2. Thanks to Google Translate, I can agree with PE1BVQ. I never found inverted V to be a very good antenna, and none of the versions I have tested here have ever stayd up for more than a day or two. The pattern can be quite high. I suspect the tower will give you a more effective pattern. I use some aluminium grease as used for Yagi element lubrication to make a good contact with the tower.

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    1. Well I mixed 2 different topics. The inverted-V and moving my vertical to the tower. The inverted-V is mainly for NVIS contacts, so indeed it is not that good when comparing it with my vertical. But should be better receiving in a circle of 1000km. I had the idea the horizontal loop I used in previous years was better. Second part of the story is about moving the vertical and in a response the comment from Hans. It is not a 1/4 wave vertical on all bands. In fact it is a non resonant antenna with a autotuner in the feedpoint. The problem only is that I want it on the mast without the radials as counterpoise. Using the mast as counterpois can be done but in my opinion it is not a good solution. So I'm thinking of add a wire as long as my vertical as counterpoise instead of radials to create a vertical non resonant dipole. 73, Bas

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Thanks for your comment. Bedankt voor je reactie. 73, Bas