Radio Frequency (RF) & Wireless Design

Okay one of the most important issues with mounting a monopole antenna that is the most overlooked is the distance of the antenna above the Earth Ground.

https://en.wikipedia.org/wiki/Monopole_antenna

This has a dramatic effect on what is called the radiation angle (see figure 2) : http://www.hamradioindia.org/circuits/radiation_pattern.php

As you position the antenna above the Earth Ground the angle will change and will move upward. This is an effect created by the 'image' of the antenna. https://en.wikipedia.org/wiki/Image_antenna

Fortunately you have picked the easiest antenna to mount and create the best image ! Typically you want at least 1/4 wavelength distance for every 1/4 wavelength antenna length, but raising the antenna will change the radiation angel and may improve your directional distance.

So for a 1/4 wavelength 11 meter antenna, you would want 11/4 meters minimal distance (if possible) = ~ 3 meters or 9 feet - the minimal height of a single story home.

For more information about Earth Ground effects and soil conditions please refer to the Amateur Radio Antenna book chapter 2.16, 2.2, 3.2, 3.3 and there are some examples in section 3.4

http://elabweb.hpa.edu/public/projects/KH6HPA/ARRL/ARRL%20antenna%20book/program%20files/ARRL%20Antenna%20Book%2022nd%20Edition/ARRL%20Antenna%20Book%2022nd%20Edition%20Content/02.pdf

http://elabweb.hpa.edu/public/projects/KH6HPA/ARRL/ARRL%20antenna%20book/program%20files/ARRL%20Antenna%20Book%2022nd%20Edition/ARRL%20Antenna%20Book%2022nd%20Edition%20Content/03.pdf

The only other way to improve a omnidirectional antenna is either with Earth Ground radial wires buried in the dirt, a set of counterpoise metal rod radials at the base or a metal cone at the base. https://en.wikipedia.org/wiki/Counterpoise_(ground_system)

In terms of Safety Earth Grounding , for the USA its best to follow the National Electrical Code (NEC) otherwise known as following 'the code' which may also have additional local, municipal, or state codes as well.

This diagram will give you a good idea of what to do in regard to providing a Safety Earth Ground for your antenna :

https://longrangesignal.com/tv-antenna-basics-how-to-ground-an-outdoor-tv-antenna/

Unfortunately the term 'ground' has become so freakin' convoluted that its no wonder any one can make sense of it !

For your case you will actually have (3) 'grounds' :

1. RF return within the coaxial able and connectors.
2. Shield return on the outside of the coaxial cable and connectors.
3. Safety return for 'failure' modes of operation.

Note that there can be a separate 'shield' braid or foil for coax as well which reduces noise on the outside of the RF return.

Please follow the recommendations for your codes.

One of the other two things that I would highly recommend are :

• Power Outlet Surge Suppressors
• Uninterruptable Power Supply (UPS)

If you have a power outlet surge suppressor connected to the wall outlet and then connected to the UPS and then connected to your equipment. This will provide double protection for your end equipment (Radios and Computers).

But the antenna will need a lightning arrestor and a surge suppressor and therefore the only way to suppress it will be either using a BalUn and / or a Antenna Tuner which has some isolation.

There are good books by the ARRL on grounding (known as bonding in military standards) for lightning in this book : https://www.arrl.org/shop/Grounding-and-Bonding-for-the-Radio-Amateur

Thanks for the input Steven,

I have just got to dwell over if this is what I really want to do right now.

It is either this or another piece of lab equipment.

This is a difficult decision !

I have decided on a loft antenna for sure as I simply can not risk a lightning strike taking out all my lab equipment.

That would just be a nightmare.

I already have surge protection on everything from the wall sockets already.

I already study so many areas this really is a tough decision.

I think I have to install the loft antenna at the least just to enable the ability of repair work in RF. When the antenna is fitted I will consider buying the radio hardware.

Many thanks Steven

Well if you have any other questions, just let me know and I will try to help out.

The gain of this antenna is incredible at 9.9 dBi which is 9.9 dbi - 2.15dBi = 7.75 dBd over a 1/2 wavelength dipole or about 6x more gain than a 1/2 wavelength wire dipole. This is the type of gain that you typically get from a yagi directional antenna, not a monopole 'whip' vertical antenna especially without radials.

https://en.wikipedia.org/wiki/Dipole_antenna

To make sure that you are not buying an over-rated and over-hyped antenna (meaning FAKE), always ask for the radiation profile reports. Without a radiation report showing the horizontal (azimuth) and vertical (elevation) patterns, it may be spec trickery. This is true even if "in broadcasting monopole antennas 5/8 = 0.625 wavelength long are also popular, because at this length a monopole radiates a maximum amount of its power in horizontal directions."

https://en.wikipedia.org/wiki/Monopole_antenna

Also be aware that radiation pattern reports have to be comparing apples to apples in regard to output power (current, voltage) as well ! This is true even with the best of conductors (silver platings), low ESRs or all components, and large radiation areas.

Since "The load impedance of the quarter-wave monopole is half that of the dipole antenna or 37.5+j21.25 ohms." one would expect the maximum output radiation is at least 2x and maybe up to 4x, so something doesn't make sense here !

But even then review other reviews of distance performance from others that have used this antenna to see the coverage.

Any good antenna will have many backers and endorsements that match the sellers claims.

And seeing how this massive Avanti Moonraker 4 hybrid quad quasi vertical/horizontal yagi antenna has only 14.4 dBi, I am thinking that your antenna is pushing the bullcrap meter to the limit !

https://worldradiohistory.com/hd2/IDX-Consumer/Archive-Radio-Electronics-IDX/IDX/70s/1977/Radio-Electronics-1977-11-OCR-Page-0116.pdf

And even this antenna with radials has only 5.14 dBi but its rated for 10,000 watts so you can really blast your way thru ! :-D 

https://zerofive-antennas.com/product/colossal-10k-5-8-wave-heavy-duty-groundplane-antenna/

Also in the amazon reviews for this antenna it shows the very small coax (probably silver plated) that connects the base to the top !

https://www.amazon.com/Sigma-Master-FIBRE-STATION-ANTENNA/dp/B01M8JXWW1

whereas much better antennas are made from aluminum tubing such as this one :

https://mfjenterprises.com/collections/cushcraft/products/ar-10#product-manuals

which as a reasonable 3 db (2x) over a 1/2 wavelength dipole typically due to the lower radiation angle of the 5/8 wavelength antennas.

Also if you are looking for a good place for antenna reviews eham has excellent reviews for many products including antennas :

https://www.eham.net/reviews/view-category?id=13

Hello Steven,

I have just got back. I spent the weekend at our

family home outside the city celebrating our daughter’s birthday. Just before I left, I purchased the Sigma 2011 Skip Master 5/8 wave

antenna from Sigma Euro-Com. This was before I realised your latest posts. The antenna has many good reviews online but this is only a starting point. I do agree the dbi claims of the antenna are more than likely bending the bs meter somewhat. I am really restricting myself due to the space limitation of a loft area.

I have gone with RG213 Low Loss 50 Ohm Coaxial Cable rather than the cheaper coax to reduce signal losses as much as possible considering I am intentionally working with a limited and restricted budget just to get this setup operational.

I should have spent way more time researching on this but I have not been feeling my best recently. I am simply more enthusiastic with the electronics side rather than being on the air. This simply enables experimentation and diagnosis/testing for me in this area and motivates me to expand my knowledge and lab in this area in future.

Many thanks for the help though Steven.

Jason ;

Sorry to hear that you are not feeling your best, but just bear in mind that any wire (or rusty nail - see the youtube video comparison) is an antenna, maybe just not a good one, so anything will work, it may not just be what you think it is or that it will live up to the claims. I just don't want you to be disappointed if you are trying for long range.

The 11 meter band is similar in how the 10 meter band performs, especially for sporadic -E long distance communications https://en.wikipedia.org/wiki/Sporadic_E_propagation

I still recommend looking into a nanoVNA (2-port VNA) or mini1300 antenna analyzer (1 port VNA) to experiment with building your own wire or tin can antennas.

Also if you are looking for the best cable, choose the LMR series as it costs a little more, but has the lowest losses. The larger the number (e.g. LMR-400) the larger the diameter of the cable (e.g. 0.400") and the lower the losses, but the more expensive and the heavier the cable. Also try to use the least amount of cable as possible to reduce losses.

If your antenna is tuned correctly, you should NOT need an antenna tuner which will waste more power.

As a final note keep your antenna as far away as possible from all metal since any metal will detune it and throw it off the center frequency.

Hello Steven,

I have seen the video from one of your previous comments on fake antennas where the guy used a nail as a Wi-Fi antenna when testing with a network analyzer. Very good video.

To me this is simply a test platform and something to experiment from. With this little project I intentionally restricted my budget so there is no disappointment either way. I would have preferred to make my own antenna and I am sure I will be doing this in future.

I will be testing this antenna so I will keep you posted.

Jason ; Sounds good. Also be aware that many copper pipes can be assembled very easily to perform antenna functions.

I was thinking of modeling this antenna that won the ARRL cover award and it is made of copper pipes :

http://www.arrl.org/news/view/w6nbc-wins-december-qst-cover-plaque-award

Best of luck and hope you stay well.

Steven

I found this project antenna when you want to experiment that covers 11 meters too :

http://www.iw5edi.com/technical-articles/58-vertical-ground-plane-antenna-for-10-meters

This link describes the basic electrical principals and basic equations for the 5/8 vertical antenna calculations :

https://www.pa3hcm.nl/?p=902

but for the matching network you can use this calculator :

https://www.eeweb.com/tools/l-match/

Jim ;

I couldn't agree with you more in regard to directivity !

Also for those who can't make up their mind, a V-dipole or inverted-V dipole will also work to gain a little of each polarization. And you can have (2) dipole orthogonal to each other with a coax switch to each and just switch between each for best reception.

Overall there is no replacement for a yagi with as many elements as you can afford to build and put up. And if there are (2) rotator motors with one for horizontal and one for vertical directions it can be moved for best performance.

The mystery of antennas is not hard once you know the basics, but building the best antenna is very challenging !

Also here's an article comparing a horizontal dipole to a inverted-V dipole https://www.onallbands.com/dipole-vs-vertical%EF%BB%BF-which-antenna-is-better/