Creation of an inverted L antenna on 160m

Finally I am able to construct an almost perfect inverted L antenna for 160m, taking into account my preferences :

1. Have resonance nearto the FT8 frequency (1840 Khz)

2. Keep the vertical part at about 15m in order to survive winter storms.  I don't want to pull up and down the tower depending the weather forecast

3. Foresee around 30 radials of 1/8 wavelength

This is the final result : 

and in real the base looks like this :

But before the final result, there are some intermediate - sometimes frustrating - steps.

For all beginners, this is a quick manual :-)

Step 1 :  Cut the wire to the preferred length via the trial and error method.  

Because this is an inverted L, it is quite easy to shorten the horizontal part of the wire.

Once this is ok, the result seems very fine.  Resistance close to 50 Ohm, SWR 1,7, clear dip nearto the FT8 freq.

But ! The efficiency of the antenna is very low when you use it like this.  Without radials, ground losses are far too high.  In my starting years, I would have stopped at this point,  focussing on good SWR and not too much labour.

Step 2 : Add radials

There are many articles on the internet about the installation of radials on vertical antennas.  It seems that up to 24 radials, you can place 1/8 lamba radials in stead of 1/4.   I have 32 x 21m radials.  The only reason is that I had the radials ready in the box, used for my 80m vertical.

As predicable, but not making happy, the resistance of the antenna gets down to about 15 Ohm.  SWR raising up to 3.5, too high to connect to a linear amplifier.

Step 3 : Add a coil between to hot side and ground.  

This is also known as the hairpin method.  I used a coil from my Butternut vertical.  It's also a bit trial and error, the result is not perfect at all, but it lowers the SWR to 3.  

The resistance stays low, creating possible (too) high currents.   It this point it must be possible to use the antenna with a tuner inside the shack.  Remark also the BALun used to avoid unwanted radiation on the coax.

But this is not the correct use.  There is a better solution

Step 4 : add a 1:2 UNUN

Final step : I contacted Hugo, ON7FU, a real specialist in transformers.  He was capable to make a UNUN within 1 day.  Fantastic job, I could use it during the CQ WW CW contest.

Replacing the Balun by the Unun, resistance goes up to 49,5 Ohm !!  :-)   SWR 1,07, no tuner needed, no EMC risk and high power available at the antenna.

The dip is on 1831 Khz, nearto 1840 Khz for FT8 and perfectly usuable for running in the CW contest.  

Most important (see my blog about the windom antenna on 160m, with changing SWR depending on the weather)  : This antenna stays tuned.  No changes in impedance due to rain or other influences.

  

 

But the proof of the pudding in is the eating...

 

New objective for the coming years : 160m DXCC

Magic Band DXCC goal achieved !  One year earlier as expected.

So time for my ultimate HF challenge : DXCC on Topband.

During the last years, I collected some hardware to play on topband, but all of this stayed the boxes.  

Since this weekend I'm migrated to only one band : 160m.   
Steppir and 30m vertical stay operational in case of a new ATNO DXCC, but are not connected to the shack.

On my first coaxial hardline I've an inverted L, the second hardline provides connection to a remote switch with the possibility to connect up to 4 receive antennas.

As always my 2 basic principles are implemented : 

1. Keep it as simple as possible.  No complex array solutions, beverages only if really needed.

2.  Follow the Pareto principle.  20% effort to achieve 80% result.  Therefore I don't want to work 300 countries,  I just want 100 countries, no WAZ, no WAS even not a WAC if too difficult.

At this time I've 63 confirmed countries on topband.  

New Milestone : DXCC on 6m band

 Finally !!! 

I took hours and hours of listening, sometimes being on the right time on the air, sometimes being discouraged when openings were detected from my city-qth... but last weekend was my lucky day.

A big opening to Africa delivered Togo and Gabon on 6m.  Gabon directly confirmed, Togo to be confirmed within a few days.  DXCC 6m status from  98 to 100.  One little regret : I missed EL, Liberia, 2 minutes too late in my shack, but the opening was gone, just like the EL station.

It ends like it started : with my steppir.  I had never expected such a big opening in the middle of November.  My 50Mhz 6 element yagi lays on the ground since a couple of weeks to save it from winter dammage.

But I added the extra six meter element on my steppir and this was sufficient (needed ?) to work the two new countries.

In 2022 I added LU, BA, PJ4, TR, JW, FP, C5, S01, 5V,  and both OH0 to my list.   

C5 and JW were made in FT4 mode.  All 98 other countries in FT8.  The is my first full digital DXCC.

Ending 2022 with a 9-Band DXCC.  Sounds great !

DXCC 316 : Equatorial Guinea confirmed

Finally 3C in the log.  Never had the chance to work this country, but last weekend 3C3CA was in the air.  DXCC 316 confirmed via LotW.