Hacker News Reader

Comment by jimmcslim | Hacker News Reader

I'm interested in amateur radio but always feel that I can't get anything done without a big honking antenna?

For VHF and UHF , that's not generally true - e.g. a simple quarter-wavelength antenna (exactly what it says on the tin - a stick antenna that is 1/4 of the wavelength on which you intend to operate - so e.g. for VHF 2m band, we're talking ~20" long, and for UHF 70cm it's even shorter) is perfectly sufficient to work repeaters, and to communicate with others directly within the radio horizon.

For HF, you do need a large antenna, but it's not necessarily what people think of when they think "antenna" - i.e. not a tower with a giant vertical rod. An HF antenna can just be a piece of cable of the right length and type, properly arranged; and it's usually strung more horizontally than vertically. Using trees for that is pretty common, too. Something like this:

https://hamcall.net/images/BuckmasterOCFInstallDiagram.png

>For VHF and UHF,

For VHF and UHF it matters that your antenna is very high up (on a pole, roof, or whatever w/line of sight if you want more than a couple blocks) more than your antenna 'size'. So even VHF/UHF/Microwave you still need something "big" unless you're just communicating with your next door neighbor.

There's no magic in RF. The cell system for phones only works because they pay the big bucks to put cells on every high point they can.

If you hold the transceiver in front of your head while speaking (as you naturally would), that already gives you 2-3 miles of radio horizon, depending on your height. If the person you're talking to does the same, that range doubles. Of course, that's on flat ground, without hills etc getting in the way... but still, you're usually looking at a mile or two of range, at least.

http://www.miklor.com/COM/UV_HowFar2.php

https://hamradioschool.com/how-far-can-i-talk-with-my-radio/

And, of course, beyond that, you'd just use repeaters anyway. There's no shortage of VHF and UHF repeaters, and because they take care of antenna height on their side, it's not uncommon to hit one 10-15 miles away with a handheld.

I'm not a radio/antenna expert, so this might be a bit inaccurate.

You want your antenna length to be some fraction of the wavelength, e.g. 1/1, 1/2, 1/4, etc. As the antenna length fraction gets smaller, it will have a less signal and more noise.

Ham radio bands are much lower frequency than wifi, bluetooth, GPS, or cellular. The wavelength is equal to the speed of light divided by the frequency, so lower frequency bands need bigger antennas.

So for example, the wavelength for a 144 Mhz you might use for amateur radio voice is 2 meters, whereas the wavelength of 2.4 Ghz wifi is only 0.12 meters.

The advantage of lower frequencies is they travel farther. AM radio is a lower frequency than FM, so it travels farther than FM.

This was a barrier for me as well. There are options. I have a 65 foot wire that goes from my house to a tree. It's virtually invisible. I've had many people in my yard an nobody has ever noticed it. I've worked pretty much the whole world with it.

There are also "compromise" antennas that use inductors and other trickery to be shorter. Are they efficient? Not great, but people make contacts on them everyday. (I have a 4-5 foot antenna that can operated on the same bands as my 65 foot antenna although it's not super efficient.

There are loop antennas that are tiny and portable but they can get expensive.

Also their are people that use an antenna tuner to tune a random piece of wire or even their gutters to get a workable HF antenna.

HF (which is what this article talks about) works best with a big honking antenna, but if you build your own you can get pretty creative; my dad did 20m from a townhouse.

As far as VHF/UHF, there are compact handhelds[1] with an antenna less than 12 inches long.

1: For example https://www.yaesu.com/downloadFile.cfm?FileID=12831&FileCatI...

All situations end up being a compromise. Most HOAs abhor antennas. I have an Endfed Halfwave antenna (EFHW) strung up in a tree. I can operate 6meter to 40meter band with it pretty well.

https://myantennas.com/wp/product/efhw-4010/

Also magloops are fun but are also a compromise.

For reference, one time I had WSPR contact with Australia from the US with only 500mw and a 40' wire antenna strung into a nearby tree.

Big antennas are desirable but simple (and low) wire antennas work remarkably well, and are what most people use.

You can make loop antennas with parts from the hardware store.

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

Reply on news.ycombinator.com