Horizontal long wire MW aerial.

[Murphyv310]

https://en.m.wikipedia.org/wiki/Beverage_antenna

[pwdrive]

So far as I can make out the with the Beverage antenna the vertically polarized wave (E field) from the transmitter starts to tilt from the perpendicular as it passes over the imperfect ground, the wave tilting over produces a horizontal component in the E field, that horizontal E field is parallel with the ground as is the antenna wire and the oscillating horizontal E field causes a changing current to flow along the wire as per usual.

The far end of the antenna is terminated to ground via a resistor, the value of which matches as best as possible with the characteristic impedance of the line, that terminated end should point to the favoured direction of the transmission(s) the receiver end needs to be matched too.

In depth there's a bit more to it! but that's the basics as I understand it.

So....would Colly's horizontal short antenna have responded in a similar way...it might have done...?

EDIT: Post crossed....!

Lawrence.

[Crackle]

Going back to my situation, what would be the effect of dangling a vertical drop from the end of the horizontal about a foot out, say, from the wall before the wire passed through the window frame? The bottom end would need to be tied down to prevent it waving about, I imagine, as it would have been if the connection to the receiver was at the bottom in a conventional set-up.

What is the opinion on this idea.
I have the same situation with my radio workshop room in an upstairs bedroom and a wire going out through an air brick to a tree 10m up the garden terminated with a piece of strimmer nylon line.
Should I add a drop down the side of the house and keep the connection to the radio at the corner of the horizontal and vertical parts?


Mike

[pwdrive]

Sort of an inverted L Windom

Not sure what the effect would be, try it and see.

Lawrence.

[Crackle]

Its not so easy to get to with out ladders. But i may be able to feed enough out from indoors to drop the aerial down to attach something.
Mike

[Pat Pending]

Going back to my situation, what would be the effect of dangling a vertical from the end of the horizontal about a foot out, say, from the wall before the wire passed through the window frame? The bottom end would need to be tied down to prevent it waving about, I imagine, as it would have been if the connection to the receiver was at the bottom in a conventional set-up.

What is the opinion on this idea.
I have the same situation with my radio workshop room in an upstairs bedroom and a wire going out through an air brick to a tree 10m up the garden terminated with a piece of strimmer nylon line.
Should I add a drop down the side of the house and keep the connection to the radio at the corner of the horizontal and vertical parts?


Mike

I really think that it would not improve the performance much.

This is hard for some to take but.. If you have an upstairs "radio shack" with a purely horizontal aerial, and an earth that runs from the shack downwards, the run from the set to ground acts as an antenna to vertically polarized signals, these signals are generated against the earth, just as if it were a capacitive "hat" and, via the sets input, the capacitive loading of the longwire works to complete the system circuit just as the earth does.

If you would prefer a traditional inverted "L", then take the vertical down at the far end of the horizontal portion of the aerial, thence through a WB transformer to earth, then take the secondary back to your set via a parallel feeder or possibly a twisted pair, you also have the option to use a blaun if you wish. Bringing the signal from the far end of the system gives you the option to reduce building e-field rfi.

If you support the wire on the building use a length of non conductive cable or rope, to hold it away as far as practical, (nylon cored linen line is good, with glass or glazed ceramic insulators), not only will it help reduce signal loss, but it will reduce the likelyhood of damage to property from lightning strikes.

Andy.

[Murphyv310]

Why not try the EWE aerial. http://www.dxing.info/equipment/ewe.dx
This worked well for me even in my electrically noisy area.

The site itself is an interesting read.

[pwdrive]

I'm not sure of the theory described in the link, can anyone explain a bit better?

Lawrence.

[reset]

My simpleton theory goes like this. The resistor varies the electrical length of the antenna by 'slowing' the signal as it goes to ground. As the length varies the reflection changes phase and causes the standing wave to shift. The radiation pattern shifts so you can use a pot in the place of the resistor and create a directional antenna. We had a discussion of flag antennas on TRB and I did these simulations.

http://radio.radiotrician.org/2016/06/di...tenna.html

http://radio.radiotrician.org/2016/06/tu...rn-by.html

The only thing about the flag to be aware of is the ratio of the L to H.

[Crackle]

I think I will be leaving the aerial alone as a simple straight long wire.
There are difficulties installing a "drop" near the house, and it would require some ladder work. The idea of adding a drop at the far end is interesting, but I cant help feeling that here will be appreciable losses in a 40 foot run of coax buried in the ground and back up to my room, so that does not seem very practical in my case either.
Something which may help is trim the branches back on the tree which have overgrown and are now shielding the far end of the wire.

Mike