Half dipole antenna - stainless steel wire with copper wire twisted around it?

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
I am wondering if I make a half-dipole HF antenna in my yard can I use stainless steel wire for the two lengths and then simply "wrap" or "twist" copper wire around that?

The copper wire would likely be insulated too.

This way the steel takes the strain, tension while the copper becomes the actual conductor.

Thoughts?
 

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
Hmm, reading this strongly suggests I can forget about the copper.

1642271048268.png

Seems at these frequencies the different metals' resistivities are of marginal significance.

Not that it matters, but this is not for transmitting, I'm purely interested in DXing.
 

SamR

Joined Mar 19, 2019
4,127
For years I have been using bits of a 500' spool of green #12 THHN/THWN wire. Green to help it blend in a bit, #12 because @ `100' it doesn't seem to stretch, and THHN/THWN insulation because that is how it came and does give it a bit of protection from limbs rubbing against it when windy. At one time I used some expensive copper clad steel wire but the copper got nicked and the steel rusted and it came down after a few years. I've got wire antennas (slopers, dipoles, end fed) that have been up for ~20 years and survived hurricanes that took my verticals down. And you can't even see them unless you are looking hard for them.
 

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
I can also see there's a kind of antenna named a "fan dipole" which seems like a great way to receive across the HF bands...
 

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
I also live in the southwest, my house/roof is not too dissimilar to this:

1642283755937.png

So the more I think about this more it seems I can just run the antenna across the roof, say to a couple of rigid posts mounted on top of those "walls" that surround the roof. Not sure if that would be worse than running from the building to some part of the yard.

I wonder if the wire being close-ish to the masonry would be bad...
 

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
This is what I mean, imagine the red line is the full length of the antenna (there'd be a split etc in the middle of course):

1642284484668.png

So if that total length was say 10m (each "leg" approx 5m) , that would represent a wavelength of 20m and correspond to a frequency of 15 Mhz, round about the center frequency of the HF bands.

I'm thinking I'd have sturdy poles about 12' tall, mounted on the edge walls of the roof and use egg insulators to actually attach the wire to them.
 

SamR

Joined Mar 19, 2019
4,127
You have to remember that even a 1/4 wave 80 meter dipole is ~ 150' long. I'm currently using a BUCKMASTER DX-OCF-HP 7 BAND Antenna HF Wire Multi-Band, DXOCFHP 7 BAND (hamradio.com) which is 135' long. If you are only looking to receive a simple longwire with one of these antenna tuners with preamplifier MFJ MFJ-1040C Receivers Accessories, MFJ1040C (hamradio.com) works well and allows 2 radios, 2 antennas, and works with transceivers up to 125W transmit. If you are interested in 10M you will find most using a vertical antenna and a good CB antenna will tune to 10M and work better due to orientation.
 

Reloadron

Joined Jan 15, 2015
6,531
To add to Sam's post. You can find everything you need to know about dipole antenna length here. Then wavelength to frequency or vice verse here. Then the popular 1/2 or 1/4 wave antennas. My first was AWG 12 from a large maple in front of the house to a large black cherry in the backyard. Using an old clothesline pully with a cinder block for tension on one end. :) I was on Long Island NY and limited to north and south radiation. You may want to consider how your antenna is aligned. Also as Sam mentions when you get to 10 meters a vertical whip is a good consideration.

Ron
 

nsaspook

Joined Aug 27, 2009
9,466
I can also see there's a kind of antenna named a "fan dipole" which seems like a great way to receive across the HF bands...
Sure, a fan antenna will be OK.

You don't need electrically tuned standing wave antennas. What you need is something that's an effective radiator and receiver of EM energy at X frequency and a device to match that to the required impedance for transmit or in some sensitive signal cases matching to deliver the required input signal level for receive. A classic long-wire SW antenna will work well for DX in most cases.
 

SamR

Joined Mar 19, 2019
4,127
Or if you prefer to go old school and tune the antenna instead of RCL matching the radio to the antenna get one of Amazon.com: SDRGEEK Nanovna-H4 Vector Network Analyzer 10k-1.5GHz with 4"Touchscreen for Antenna Analyzer HF VHF UHF Standing Wave Measuring S Parameters Voltage Standing Wave Ratio Phase Delay Smith Chart : Industrial & Scientific to tune your antenna. Nice toy that I have yet to play with my antennas with. Much better than the old Grid Dip Oscillator Meters we used to go by. Bit of a learning curve even if you already understand antenna tuning. You can also find several of the ARRL antenna books online in PDF.
 

MisterBill2

Joined Jan 23, 2018
11,602
The fact is that everything matters and everything makes a difference. BUT the other side is the question of HOW MUCH difference. For transmitting that is more important. With a good receiver the difference is still present but not nearly so obvious,

For a receiving antenna, the farther away from noise sources is more important, so that is a consideration. How electrically noisy is your house? Hearing signals is a matter of them being "above the noise floor." So either raising the signal amplitude or reducing the noise level will help. There are volumes of wisdom concerning both sides available.

Resonant antennas are simpler to match, and that can be quite a benefit with transmitting operation, where a lot of power is involved. Transmitting antena will have sections with higher currents and higher voltages, but receiving antennas do not have those problems.
The classic fan dipole is a very convenient way to have the benefits of resonance and near resonance at a number of frequencies. The compromise is that it takes more wire, more insulation, more effort, and more support for fan dipole. But the benefits are longer lasting, the work and expense are one time.
An important part of any antenna is the "feed line" that connects the antenna to the radio, either receiver or transmitter. Losses in the feed line do matter. "Power lost in the feed line is gone forever."
This is another area where a lot of insight is available.
 

Reloadron

Joined Jan 15, 2015
6,531
Sure, a fan antenna will be OK.

You don't need electrically tuned standing wave antennas. What you need is something that's an effective radiator and receiver of EM energy at X frequency and a device to match that to the required impedance for transmit or in some sensitive signal cases matching to deliver the required input signal level for receive. A classic long-wire SW antenna will work well for DX in most cases.
OK, a wet noodle. :)

Ron
 

SamR

Joined Mar 19, 2019
4,127
A very popular antenna when guys started building and using tuners was the aluminum lawn chain antenna. Proving that with a tuner almost anything can be tuned to be a transmitter antenna. The MFJ-1040C preamp and tuner I have for my ICOM IC-R75 all band receiver is nice because it will switch between 2 antennas and for use with it, I have an N/S sloper and a E/W longwire. Thinking about adding a VHF/UHF discone antenna for IC-R75. Even though I do not need to tune to a transmit frequency I do get a few dB of gain by tuning the MFJ-1040C plus it has a preamp and noise suppression before it gets into the radio circuity. Plus it can handle 125W transmit but my 100W ICOM IC-7410 XCVR has autotune built into it so don't use it for the XCVR. They make several more expensive models with the cross needle SWR meter for the higher-powered transmitters but I'm already using a cross-needle Diawa Wattmeter and the XCVR internal autotune does a great job. They also made the IC-R75 RCVR in a XCVR model with basically the same wide band all-mode receiver plus a 100W XMTR. For the IC-7410 I use the multiband off-center dipole plus I have a 28' 10M vertical on top of a 30' mast. Plus, a marine ICOM 25W VHF with a vertical mounted near the roof peak so the wife can contact me offshore out of cell range. Also a SDR dongle that I play around with. Also have Ham Radio Deluxe software that I can use with the IC-R75 and IC-7410 for band scanning on my computer and a few other neat tricks it does.
 

MisterBill2

Joined Jan 23, 2018
11,602
The "Wet Noodle" and "Wet Rope" antennas are poor choices, mostly used to demonstrate what can be done, not what works best.
As many interference problems have demonstrated, anything can work, sort of. But certainly an antenna clear of conductive surroundings and above assorted obstacles will perform much better. Adequate insulators and good connections to a lower loss feed line will make the biggest differences, and being resonant at the desired frequency is a benefit, and may aid in rejecting noise that is not at the desired frequency.
And a "standing wave antenna" is not a term I have heard very much. Is that the same as a well matched resonant antenna, I wonder?
 

Thread Starter

ApacheKid

Joined Jan 12, 2015
617
The big challenge here is that it does involve a lot of experimentation. I can't really know if an X is better or performs better than a Y until I'm able to compare them.
 

nsaspook

Joined Aug 27, 2009
9,466
The "Wet Noodle" and "Wet Rope" antennas are poor choices, mostly used to demonstrate what can be done, not what works best.
As many interference problems have demonstrated, anything can work, sort of. But certainly an antenna clear of conductive surroundings and above assorted obstacles will perform much better. Adequate insulators and good connections to a lower loss feed line will make the biggest differences, and being resonant at the desired frequency is a benefit, and may aid in rejecting noise that is not at the desired frequency.
And a "standing wave antenna" is not a term I have heard very much. Is that the same as a well matched resonant antenna, I wonder?
I spent time in the 70's-80's on a several communications ships and stations often with HF transmit and receive antennas in close (several hundred few at most on ships) proximity. Because of the wide-band coverage needed we seldom used resonant standing wave antennas.
http://empossible.net/wp-content/up...g-Wave-and-Frequency-Independent-Antennas.pdf

https://www.navy-radio.com/ant/ant-lph2.JPG
Fan wire antennas.
https://www.navy-radio.com/ships/ffg7/ffg39-ant-fan.JPG
 
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Thread Starter

ApacheKid

Joined Jan 12, 2015
617
I spent time in the 70's-80's on a several communications ships and stations often with HF transmit and receive antennas in close (several hundred few at most) proximity. Because of the wide-band coverage needed we seldom used resonant standing wave antennas.
http://empossible.net/wp-content/up...g-Wave-and-Frequency-Independent-Antennas.pdf

https://www.navy-radio.com/ant/ant-lph2.JPG
Fan wire antennas.
https://www.navy-radio.com/ships/ffg7/ffg39-ant-fan.JPG
Just as I remember, antenna/ariel theory is pretty involved. But a very interesting PDF Spook, thanks.
 

DickCappels

Joined Aug 21, 2008
8,686
I would be worried about the two metals oxidizing resulting in intermittent contact between the two. That could eventually result in intermittent changes in the tuning of the antenna that means NOISE which is what you don't want. Best to go with wire that others have been using.
 
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