Summer wind

[KB2WIG]

 Beautiful weather hear today. I might open a few 807s and sit in the backyard today. If the XYL says its OK......  Anyway,  it's getting close to antenner weather here near Sorrycuze - and I want to be able to start after the first snowfall.

Orr in his Radio Handbook has a Twin-Lead Marconi antenna. To paraphrase, '  ..The radiation resistance is raised  from ~ 10 orr 15 ohms to 40 to 60 ohms - The ground loss is reduced by a factor of 4. '  Whatt he du is cut 1/4 wave of 300 ohm twinlead, short the far end and feed the other end with 52 ohm coax.    The twin lead length =  234/F_(MC)   He goes on to say that a gud ground is needed. I'm thinking of implementing it as an "L". The pic in the book kinda looks that way.

Any usefull comments on using this thing on 160?  I know a 1/4 wave vertical with a radial every 3 degrees would be nice; but I dont have that much $cratch.

What do be do be u do?

klc

[Steve - K4HX]

Other than a feed point impedance that is closer to 50 Ohms there is no advantage in this system over a regular single wire Inverted-L. There will be no reduction of ground loss. What is stated about these folded L's is incorrect. The ground loss is completely determined by the soil and the radial system.

[Bill, KD0HG]

What Steve said..
Radiation resistance is *not* the same as feedpoint impedance.

Stick with a traditional inverted-L and a tuner.

The key thing is to install as good of an RF ground as possible under the L. Radials, a wire fence, a buried cast iron bathtub, an old Volkswagen.. I always liked rolls of 4 foot chicken wire laid on the ground. Stake them in and grass will grow through it. In a year you'll never know its in there. Ground rods for RF are worthless.

Inverted Ls are teriffic antennas for a smaller lot, but you need to minimize ground losses underneath them.

if you have an inverted L with 10 ohms of radiation resistance, and a 50 ohm ground system, you're only heating up earthworms with most of your RF.

Bill

[KW4DE]

A corner fed inverted L (inverted V rotated about 45 degrees) works well.  Suspend the corner as high as possible and feed with coax or  open line.  In essence you have a quarter wave vertical fed at the top so no ground loss and you have a horizontal quarter wave that gives you some higher angle for local QSO's.  Easy and efficient.
Darrell KW4DE

[Steve - K4HX]

Any, repeat, any vertical radiator, no matter where it is fed or its length relative to a wavelength is subject to ground losses. Changing lengths and feedpoint heights only change the distance from the vertical where the loss is greatest. Use designs where loss is greatest closest to the vertical - in other words, where your radials can do some good/reduce the losses. A raised feedpoint may be valuable if you have tall items in the near field that will impact the radiation at lower angles.

[ke7trp]

WIG, Do you have a tower?   If so, Just do a coax fed L with the sheld Grounded to the base of the tower.  Then Run the L up on rope.   I ran this way for a year.  Then later added four ground radials on the ground.  Last winter I made my L last year. It kicks A$$

http://youtu.be/SfvmwCgjjJo

I think you should try the twinlead antenna. Its cheap and will probably work. Fun and experimenting is what its all about!

C

[KB2WIG]

Nooo, no tower.    Not fer a few years anyway.

I'll be going with a EL if I can hack enough real estate. Chicken wire and bathtub? I do have an axle in the back woods. I think the MOP used welded fence wire for a ground mat. Anyway, the ant location is wooded and not easy to dig up.  I'll probably lay wire on top of the ground and hope the deer don't trip on it.   The beverage may go in if I dont get an attack of the Lay-Zees.

Thanks fer the input.


klc