Which is best – An EFFICIENT antenna or an EFFECTIVE antenna?

What’s the difference? An EFFICIENT antenna is one that converts as much transmitted energy as possible into radiated RF energy. “Efficient” is not clearly defined but is often understood to mean more than 90%. An EFFECTIVE antenna is undefined. The term is subjective and could refer to a favorite antenna that “gets the job done”. If an antenna brings in the QSOs it could be described as “effective”.

Even an efficient antenna won’t guarantee we will make QSOs. It is quite possible that an inefficient but effective antenna will bring in more QSOs than an efficient antenna. How can this be so?

To answer that question we have to examine the factors that affect the effectiveness of an antenna. These factors are unrelated to whether an antenna is actually efficient (although efficiency certainly helps).

Propagation Conditions: When our friendly neighborhood star gets hyperactive and hurls, for example, CMEs (Coronal Mass Ejections) in our direction things can get quite difficult for radio communications. We have witnessed this frequently during the recent maximum of the 11-year solar cycle.

As an aside, many ancient civilizations worshiped the Sun as a god. In the absence of our advanced technologies perhaps they could be forgiven for doing so. In terms of volume, the Sun is a million times larger than the Earth (source: Encyclopedia Britannica). It sustains all life on Earth and at some point in the distant future it will destroy the Earth when it runs out of the fuel that keeps its immense internal fusion reactor working. At that point it will swell into a red giant encompassing the orbits of all the inner planets.

But back to the Sun’s effect on radio communication, it controls which bands are active at any given time. It controls whether the ionosphere has the ability to refract RF back to the Earth’s surface, and to what degree. It doesn’t matter what kind of antenna we are using when a solar storm creates an HF blackout. For that reason it makes sense for amateur radio operators to pay attention to propagation conditions when planning to operate. Ham Radio Outside the Box discussed what all the propagation parameters mean in an earlier post. Personally, I pay particular attention to the Solar Flux Index, Sunspot Number, K-index, Bz (Interplanetary Magnetic Field) and the Solar Wind Speed.

How many stations are on the air?

There are times when the “band is dead”, meaning if we scan the band we don’t hear any activity. Sometimes, all it takes is for one station to call CQ and the band joins the “undead”. At other times there just ain’t nobody listenin’; for example, Superbowl Sunday may not be the absolutely best time to get on the air. On the other hand, during ARRL Field Day in June the bands are usually a tad busy. I once made the mistake of waiting until Field Day was over before starting a POTA activation. Of course most Field Day stations had gone off-air by then so I ended up with a busted activation. Field Day contacts are valid POTA QSOs too so I probably could have completed the activation in short order if I had jumped on the air a few minutes earlier.

During the week many hams are at work and the bands are quieter. Those of us who, being of a certain age, are unencumbered by employment may still be disturbing the peace and quiet of the ionosphere.

So if we want to test whether our new antenna is a good’un it probably makes sense to get on the air when there are plenty of other hams pounding brass by the light of brightly glowing tubes (or “valves” as they are called in the land of the Pilgrim Fathers).

Location, location, location

As Bobby Darin might have sung if he had been a ham:

“Somewhere, beyond the sea; Somewhere waiting for me; Another ham on golden sands; Is watching the bands for me”

If you are a ham on golden sands – for example on the Atlantic or Pacific coast you can take advantage of the “Salt Water Effect” which makes even a wet noodle look like a great antenna. From my location in Southern Ontario Canada I would have to travel 1000km north to find salt water inside my own province, but that would be on the frozen shore of James Bay. Alternatively, at about half that distance, and across the US border, is New York City. I have tried operating on the beach beside the world’s largest underwater salt mine on Lake Huron but it didn’t do it for me.

If we can’t go down to the sea to CQ another alternative is to get high – as in up a mountain. Once again, I struck out. The highest peak in Ontario soars to a mind numbing, breathtaking … well actually it doesn’t even make it to 3000 feet (about 900 meters). Height helps!

What kind of antenna is the other guy using?

I remember having a great QSO with a ham in France from my backyard in Ontario. I was testing a wire antenna for NVIS that was only about 12 feet above ground. I was blown away by how clearly he could hear me. When I told him about my antenna he had the good grace to compliment me on how well it was working. A low antenna, designed for NVIS can sometimes still put out a -6dB signal (down 1 S-unit) at a low radiation angle and snag some DX. After the QSO I checked him out on QRZ.com and saw what kind of antenna he was using – it was a multi-element Yagi up about 70 feet on a tower. Now that was what I would call an “effective antenna”! It was doing the heavy lifting during the QSO, not my puny wire.

So the lesson here is, if you are operating QRP with one of those trendy 4ft base-loaded whips, and you are getting great DX contacts, it may not be your modest compromised miracle antenna that is getting the job done, it could instead be the DX operating from a powerful super station.

So could an inefficient, but effective, antenna beat out an efficient antenna? Perhaps; it is possible if the inefficient, but effective, antenna is up a mountain – or a saltwater beach for example.

What’s to be done?

Let’s get back to what makes an antenna “effective”. The millions of us who live within the interior of the great north American continent don’t have to imagine what it is like to operate far away from salt water and mountain peaks; we live it every day. Some among us have further limitations such as living in an HOA where the guardians of the establishment will descend like a swarm of screaming demons upon any ham who erects an antenna higher than a blade of grass. The custodians of many public spaces bring fire and brimstone upon anyone who dares disturb their trees, so throwing a weighted object up into the green canopy and pulling a nice long, efficient wire antenna up and over a branch is out of the question. But there is a solution.

Imagine you have to live with all these limitations and maybe even more. The best antenna you can get on the air is only 30 percent efficient. The bands are in turmoil due to a minor solar storm. If you are a QRP diehard your signal will at best be limited to a couple of watts. If you get lucky you may still make some contacts; if you don’t – well that’s the fun of QRP. A day in the park flattening your battery calling CQ with no responses is better than a day at home doing chores, or so they say.

Here at Ham Radio Outside the Box our motto is: “QRP when possible, QRO when required”. Or, to put it another way, a day in the park flattening your battery calling CQ at a blistering 30 watts and making QSOs is better than a day at the park flattening your battery calling CQ at 2 watts with no responses. That’s the fun of what I like to call QROp.

What are your experiences? Do you have a favorite antenna that gets the job done?

Coming up in a future post … A return to QRP and why I am reluctant to take my QRP-Labs QMX to the field.

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