Thank you Rick. I can see an increase in the horizontal radiation but it seems there is still enough vertical radiation.
Without load https://cloud.orange.ro/share/93be10d491e0c6b632fe49b9804e78e3?d=&c=&r=#1 With 75uH load https://cloud.orange.ro/share/e035179a07e18f4832fe49b9804e78e3?d=&c=&r=#1 (Vertical=red, horizontal=blue) I don't know what other TX antenna will be suitable for my condx: House top @29 ft, a pillar @19ft and a pole @8ft, see bellow. https://cloud.orange.ro/share/36474948adb7a57132fe49b9804e78e3?d=&c=&r=#1 I don't expect much, I just hope this INV-L will perform better than my FD3 (OCF dipole 20m long Z=1-j2600 on 160m) TNX & 73 Ady YO2NAA -----Original Message----- From: Topband [mailto:[email protected]] On Behalf Of Richard Karlquist Sent: Wednesday, February 11, 2015 1:38 AM To: [email protected] Subject: Re: Topband: Inverted-L with coil on the top of the vertical section On 2015-02-10 14:09, Adrian Fabry wrote: > The simulation (with MMANA software) indicate 3.5 +j0 Ohm impedance. > This is > very low so I think most of the power will be lost in the ground. > > In order to raise the impedance, I would insert a coil (about 75 uH) on > the > top of the vertical section and restore the resonance with 48.7 pF > series > capacitor on the feed point. > > This will raise the impedance to 34 ohm. > You have to be careful with loading inverted L antennas. What is happening here is that the horizontal top wire is now doing most of the radiating. You basically have a very low dipole. There will be a lot of ground loss due to the height. I think you would be disappointed if you built this. Rick N6RK _________________ Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
