Antenna Gain

Newer amateur radio operators may read or hear some discussion of antenna gain.  The gist of it usually involves how much stronger signals are with a particular type of antenna.

This concept of antenna gain can be confusing or misleading to new hams because it sort of suggests that some antennas actually amplify received or transmitted RF signals.  Not so.

Like the decibel (dB) antenna ‘gain’ is always relative.  So when we speak of antenna gain it refers to a performance improvement compared to a different type of antenna.

More commonly, gain is used to compare highly directional antennas (beams, dishes) to monopoles or dipoles.


While antenna gain usually emphasizes directivity it may also be used to compare two similar types with different characteristics, as efficiency is another contributing factor.  For example, we can observe and measure the relative gain of a stubby “rubber duck” handheld radio antenna (pathetic) vs. a 5/8-wave whip (much better) even though they are both vertical monopoles with the same directivity.

The two types of antennas usually referenced against are isotropic and the simple dipole.  When measuring performance of other antennas, they will often be compared to one of these two.


If the gain impovement is relative to the theoretical isotropic antenna, the units should specify the gain as dBi.  If measured against a dipole antenna, the gain should indicate dBd.  Any other comparisons should mention the reference antenna in the text.

Some good references for antenna gain are given below: Continue reading

Mic Fright and Your First Contact

Mic fright is a general term for anxiety leading to freezing, choking or hesitating when speaking into a microphone (mic).  The psychological response of worrying about saying the right thing to an audience large or small is very natural and expected.


Mic fright or shyness is a reality in public speaking, stage performance and similar situations.  Of course, it’s an important topic to new amateur radio operators so let’s provide some perspective and encouragement here.

Making that first voice contact over the radio can be an anxious moment for many new hams.  This can also carry over into the first several radio contacts where you worry about saying the right thing and following the rules.

First off, don’t let the “rules” make you nervous.  It mainly comes down to proper identification which means giving your call sign every 10 minutes during an exchange and at the end of your last transmission.  That’s pretty easy to remember.

Second, every ham was a newbie once and remembers what it was like not knowing exactly what they were doing.  Most will be patient and helpful, giving coaching and gentle reminders along the way as needed.

For general phone (voice) contacts, there are no real procedures and formalities to worry about; it’s more conversational, much like a phone call.  While radio amateurs often use jargon, abbreviation and technical terms (see our Ham-Speak topic), this is not mandatory.  Hopefully that takes some of the pressure off to make you more relaxed for your first few contacts.

A starting point for getting on the air the first time is to listen in on the local (VHF/UHF) repeaters and HF SSB bands for a few hours to learn what people say and how they say it.  If you follow these examples you are almost certain to be successful when transmitting on your radio.

An excellent way to get past mic fright and performance anxiety is to ease into it with Continue reading

dB, or not dB…

…what was the question?

Whether ’tis nobler in the mind to understand dB or just plod along wondering what the heck other hams, publications and spec sheets are talking about is up to you.  With all due respect to Shakespeare’s Hamlet, decibels (dB) are a frequent subject in ham radio.  All three US license class exams have questions involving dB in their pools.


Hams new and old don’t have to be technical experts but all should at least be familiar with the decibel.  To that end we will give a simplified explanation here.

Decibels (dB) are a convenient and standardized way of measuring a change or difference between two conditions.  In audio,  radio work and electronics in general, we are often dealing with very large or very small numbers and the difference between them can be many digits long.  To make the numbers more manageable, expressing ratios of large and small values is better done using a non-linear logarithmic scale.  Logarithms are based on orders of magnitude (10,100,1000,10000… and 1/10, 1/100, 1/1000, 1/10000…).

The human ear responds to sound logarithmically so decibels are a natural fit to measuring sound levels.  Similarly, radio work behaves non-linearly in some ways so the logarithmic approach works well here.  We’re stuck with dBs, like it or not.  In amateur radio the dB is commonly used in context of amplification, feedline loss, antenna gain, filter bandwidth and RF signal strength.

Technically the decibel is a ratio between one state and another; it’s not an absolute measurement, it’s relative.  Always ask, dB relative to what?, because this is a ctitical factor.

More practically it often comes down to the amount of amplification or attenuation.  In amateur radio it almost always involves power changes so we will focus on this aspect.  Decibels can also apply to other units such as voltage but this gets a little more complicated and not as widely used in ham radio.

A power ratio is simply comparing two Continue reading

RF Connector Types

The plug that is used for terminating cables between the receiver, transmitter or transceiver and the antenna is generally referred to as the RF connector because it carries the Radio Frequency signal to/from the equipment.

In addition to mating the radio to the antenna via a transmission line (usually a coaxial cable) it may also used on RF test equipment (antenna analyzer, power and SWR meters, spectrum analyzer) and dummy loads.  All hams should be familiar with different RF connectors so we’ll give a brief high-level description here.

Good news!  There are only four common types of RF connector used in ham radio:


220px-uhf_pl_connector     250px-uhf-connector

By far the most common RF connector, the PL-259 is used to connect most all modern HF transceivers and VHF/UHF mobile rigs to the antenna.  The PL designation stands for plug and the 259 is an old US Signal Corps assignment.  It has a male center pin and female thread.


The mating  receptacle found on the radios and equipment is known as a SO-239.  SO for socket, it features a female center receptacle and has male threads.


The PL-259 and SO-239 combination (details here) is frequently referred to as a “UHF connector” although this designation comes from the 1930s when UHF was considered anything above 30MHz.  It has performance limitations above 100MHz so other connector types are more suitable for true UHF use.


N-type Continue reading

How Far Can I Communicate?

One of the more interesting questions a new or prospective ham will have is, “how far can I communicate?”  The frustrating answer is, “it depends…” (don’t you hate hearing that?)


There are many factors involved in the limits to distance of radio communication.  Carrier frequency is the huge one, followed by operating mode, antenna characteristics and transmit power. Time of day, solar activity and the season (spring, summer, autumn, winter) also have a big impact on range.  Natural (thunderstorms, aurora, geologic, cosmic) and man-made (crowded band, power lines, noisy electronics) interference can also limit or disrupt a radio contact.  Also factor in the use of repeaters (terrestrial and space satellites) or reflective objects (structures, moon, meteor showers), plus unusual weather conditions and you have a lot to consider.

Since many hams get started using VHF/UHF radios for local communication, let’s talk about this first.  VHF/UHF radio wave propagation is normally limited to line-of-sight, meaning the antennas at each end must have a clear path between them (no obstructions such as buildings, trees, and particularly, the earth).

3-20 miles is a realistic range for VHF/UHF hand-held radios on the ground, depending mainly on a clear path and relative height of the two parties.  Throw in a repeater with a high antenna and that range extends considerably.  Raising your own antenna up higher Continue reading

Public Service Events

Are you a new ham who wants to practice radio communication?

Just getting started in amateur radio and want to learn about emergency communications (EmComm)?

Are you a ham who wants to make better use of your hobby?

If you answered yes to any of these, consider helping with a local public service event (PSE). Public Service Events provide an excellent chance to practice your EmComm radio skills.  Not only is it fun and interesting, but you will gain valuable experience in radio communications similar to a real disaster scenario, without the stress and urgency of a life and death situation.


Ham radio operators are often invited to assist with PSEs to provide primary or supplementary communication.  PSEs typically involve parades, races or large gatherings.  They normally use VHF/UHF radios so you don’t need any fancy equipment or big antennas.

Participants may be stationary  or mobile, depending on the nature of the event.  You may be sitting or standing or walking around.

Because hams supporting a PSE will often use a handheld transceiver (HT) it’s a good idea to have a few recommended HT accessories.  First would be a quality 1/4-wave antenna in place of the poorly-performing factory “rubber duck”.  Second is a spare battery pack for your radio.  Third would be headphone(s).

A must-read for new hams is Continue reading

Don’t Settle for Just a HT


Often a new ham’s first radio is a handheld transceiver (HT).  A HT represents the lowest-cost entry point to amateur radio and is relatively easy to set up and use.  Your first on-air experience as a licensed ham may involve a HT on a local VHF/UHF repeater, and that’s fine.

But don’t settle for just a HT as supplied by the manufacturer for your early ham radio experience.  You are almost certainly going to be frustrated and disappointed at its performance to the point of giving up on ham radio and wondering why all these hams are so enthusiastic about the hobby.

Don Keith N4KC makes this point eloquently  in his ‘HT Trap’ article where he discusses how easily a new ham can get discouraged with amateur radio because of the limitations of a stock HT.  I have observed this as well while helping new hams get set up in a local EmComm organization.

Huge improvements in HT performance or ease of use can be accomplished with three accessories.

First and foremost is the Continue reading