Shortwave antennas.

[alfaeire]

Howdy all, I've picked up a 15w shortwave transmitter during lockdown, and since relocated to Scandinavia.

YouTube link to transmitter


Im in a third floor apartment with a nice large garden. See attached photo.

Im new to shortwave, so I'm looking into stealthy antennas, I've seen quite a bit about random wire antennas but I can't figure out if they are primarily for DX or if they can be used for TX also?

Would a single wire antenna fit my purpose? Or would I be better off going for a v wire dipole from my window down into the garden? And does the wire(s) need to be a measured length or is basically use as much space as possible?

Running down the center of the garden (top to bottom in the photo) is a wooden fence standing at about 6 foot in height I was thinking of anchoring the end of the wire to, so it's out of reach along the path routes.

Any information or anything I might have overlooked would be a great help.

Many thanks.

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[Albert H]

Traditionally, a quarter-wave long wire works quite well. However, this presupposes some kind of earth mat or counterpoise to work against.

Remember - you're not looking for local coverage: you're trying to get to the ionosphere!

My most successful aerial in a location like yours (in a London suburb!) was an inverted "V", fed as a balanced aerial (using an ARRL-designed "Un-Bal"). Ten Watts carrier / 40 Watts peak went into the furthest reaches of Europe and over to the 'States on 6915 kHz. We had a lot of solar activity that year, so the ionosphere was "hot" and the signal really skipped well. We even got reports from New Zealand!

[SidB2]

A simple dipole will be very effective, so if you're on 6MHz then it's a bit less then 12 metres each leg. I've never bothered with a balun when there's no need for an impedance transform. You can drop the ends a bit if it's too long and it won't make a lot of difference. As Albert says, you don't need the height, keeping it low will force the signal locally (NVIS propagation).
I've got a Stretchy mediumwave tx and am very impressed with it. I've heard a couple of them on SW and they sound alright, a nice little modern class E rig.

[Albert H]

Another successful small short wave antenna is the "sloper" - convenient from some sites.

Get yourself a copy of the ARRL Antenna Book. It's available on line, and has all sorts of ways of getting your signal out there. You particularly want to look at the wire aerials (they're easy to conceal). I appreciate what SidB2 says, but a balun (or un-bal) is invaluable in getting every last bit of your expensively generated RF out of the aerial! At low power, every little matters.

My earliest short wave broadcasts were done with a simple AM rig that used an ECC83 as the oscillator and buffer, driving an 807 as the output, with a simple single-ended modulator using another ECC83 and an EL34. It gave about 12 Watts carrier and 50 Watts peak, and with careful choice of frequency could be heard in many countries. I used the drainpipes to our house for the earth, and a sloping longwire through a crude ATU to get it to match. I was lucky - it was clean enough that it didn't interfere with local TVs (an easy way to get raided in those days), and I ran it at weekends for a couple of years in the late 60s, collecting listener QSL cards from all over the globe! A friendly local greengrocer provided a "mailing address" at his shop!

[alfaeire]

Another successful small short wave antenna is the "sloper" - convenient from some sites.

Get yourself a copy of the ARRL Antenna Book. It's available on line, and has all sorts of ways of getting your signal out there. You particularly want to look at the wire aerials (they're easy to conceal). I appreciate what SidB2 says, but a balun (or un-bal) is invaluable in getting every last bit of your expensively generated RF out of the aerial! At low power, every little matters.

My earliest short wave broadcasts were done with a simple AM rig that used an ECC83 as the oscillator and buffer, driving an 807 as the output, with a simple single-ended modulator using another ECC83 and an EL34. It gave about 12 Watts carrier and 50 Watts peak, and with careful choice of frequency could be heard in many countries. I used the drainpipes to our house for the earth, and a sloping longwire through a crude ATU to get it to match. I was lucky - it was clean enough that it didn't interfere with local TVs (an easy way to get raided in those days), and I ran it at weekends for a couple of years in the late 60s, collecting listener QSL cards from all over the globe! A friendly local greengrocer provided a "mailing address" at his shop!

I'm going looking for a pdf right now! Thanks Albert!

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[Albert H]

https://ufile.io/6wo2l34f

It's an .iso file of the Antenna Book - just burn it to a CD

[teckniqs]

https://ufile.io/6wo2l34f

It's an .iso file of the Antenna Book - just burn it to a CD

[alfaeire]

I'm gunna a have to mount the image as a drive... I haven't seen a blank cd in years

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