LW1DSE's home aerials (or antennas)

Electrically speaking, it is the mirror or negative of a dipole. Setting it horizontally, radiates vertically polarized waves, this is why at 144mts band where a large majority of hams prefeer or use verical polarization, I ser it horizontally. And although the elevation over ground is smaller than my colinear, the colleagues note small or no difference using one or other, during some time I used skeleton to communicate via repeaters in fone, and the colinear at packet radio wirh a BBS in Lanus (10km straight line) but several buildings and electric interference with Horacio LU7DQP (RIP last year). Digimodes usually demmand a better s/n ratio or severe slow down of the traffic will result.

Over it, the Slot Skeleton has high impedance at terminals, from here the need for 1/4 wave transformer or similar. But taking into account the 90° difference in what the radiation pattern issue, the lobes seem to be similar to a half wave dipole. In the book above cited, the author depicts it. In my opinion, the great advantage over other construction types, is the DC short circuit that it represents, being safer than a bazooka or open dipole, not accumulating static voltages sometimes being destructive for SS rigs, mainly its MOSFET first stage..
 
Thinking about to build a new 440MHz antenna, in some instances similar to the 144MHz above depicted.
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It may be a 1/4 wave for 440MHz with 4 radials, all in 3/8" or 10mm copper tubbing. The coax. magnetically coupled via a loop or link close to the bottom of the exited element. A stub couples 1/4 wave to another 1/2 w (may be several colinear elements). All DC grounded to get rid static and tin/lead soldered to ensure good conductivity. The L inverted that supports the entire set is a 2mm brass thinker, as used in the 144MHz unit. The M stains for magnetic coupling or mutual inductance as in the old good books was used.

Ideas or suggestions, welcomed.

Osvaldo LW1DSE.
 
I was wondering if maybe using a shunt feed rather than using a coupling loop might be easier?

Or were you aiming for 100% electrical isolation between the feeder and the antenna?

73, Mark...
 
Not 100% isolated, they share ground. The idea is: as a 1/4 line or multiples acts as a tuned circuit, and you can couple a tuned circuit to a small impedance coil (link as in old tube power amplifiers), then I can couple energy to and from the antenna via a link. Let's see if it's true my hypothesis.

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Holy smoke! That's one tough looking antenna!

As we say in the UK, a "belt and braces" job.

It will be interesting to see how the whole assembly tunes up. When I've built antennas for 433MHz in the past I've found that the dimensions and spacing of components can be very critical.

73, Mark...
 
Obviously, as frequency increases, difficult rises too. My idea is to pre-adjust the whole thing insede home, and when it is roughly calibrated, then test it ouside, at the mast. Let's see what happen.

I have two points to play with: size and location of the coupling link, and the height of the exited element. I suppose that with 3 degrees of freedom, a proper point of adjust I shall found.
 
The project is becaming viewable.
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Tomorrow, using a 200W giant solder iron, a good soldering to insure good conductivity. 1/8" brass screw are for mechanical mount, only.
 
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