Ok, school me on coms

[sonoronos]

I have been doing some reading and watching, and haven't quite found yet a 'good' site (well good in my mind anyway, OCD and picky I guess) that explains well the differences between other options as far as range goes, and how the wavelength transmission actually works within the atmosphere to be able to decide which one would be best suited for any given situation - which would dictate naturally where I start, since I want to learn with just one for now and then branch out.

I don't say this to be a jerk, but your questions about HAM radio could all be answered by studying for and getting your license. I really mean this in the best possible way - your questions are good questions, but they are covered in the most basic license.

By asking us to answer these questions for you before you get your license, you're asking us to cover a lot of basic ground that you can get by self study. Once you get your license, then it's probably a good idea to start asking the questions again with your newfound knowledge.

 

[DaveInDenver]

I have been doing some reading and watching, and haven't quite found yet a 'good' site (well good in my mind anyway, OCD and picky I guess) that explains well the differences between other options as far as range goes, and how the wavelength transmission actually works within the atmosphere to be able to decide which one would be best suited for any given situation - which would dictate naturally where I start, since I want to learn with just one for now and then branch out.

There are books written just about nuances of propagation and how to utilize modes and conditions to best advantage.

https://www.arrl.org/shop/Propagation-and-Radio-Science/

And I can tell you this book only scratches the surface of these subjects, each topic in this book could be a single subject of a textbook by itself. I have several in fact since my undergrad E.E. emphasized EM fields and antenna theory.

But even knowing a little as I do about the nature of RF I still learn by operating and from other hams. Just as you will, too. That ARRL book on propagation is good but it's best used to dovetail with the standard handbook, which starts with more basic knowledge.

https://www.arrl.org/shop/ARRL-Handbook-2017-Hardcover-Edition/

Then the operating manual and the antenna handbook are a good 2-volume addition to your library, along with that propagation book. Those 4 books would serve even the most dedicated Amateur Extra class operator well and probably be more technical information than you can ever practically apply. Most of it is learned on the job, so to speak.

https://www.arrl.org/shop/ARRL-Operating-Manual-11th-Edition/
https://www.arrl.org/shop/ARRL-Antenna-Book-23rd-Softcover-Edition/

 

[Chorky]

Awesome! Thank you for the great links!

 

[REDONE]

Dave is kicking out some awesome info (as an Elmer it's to be expected).

My $0.02 to add, I got the year older edition of the ARRL operators HANDBOOK at half price by going into the actual "ham radio outlet" store (the physical stores for hamradio.com). Everyone I talked to agreed that the info doesn't change significantly from year to year.

No book is as good for studying as hamstudy.org for the test. The handbook is invaluable for actually using ham radio though!

Last, I recommend getting your license, getting a radio, and then figuring out what the heck you're doing. Trying to do it in any other order is way less efficient. You can't practice without equipment, and you can't use the equipment without a license.

I'm just an adventurer with a ham radio, but lately I've been pushing my dad to get his license so we can set up some comms between the family cabin in Bailey, CO and my house in Lakewood, CO.

Without the benefit of ham enthusiast friends in my sphere of influence, it's been difficult to actualize an expanded radio skillset and capability beyond trail comms. Hopefully this will fix that. :sombrero:

 

[DaveInDenver]

You learn most about operating listening to others on the radio. I certainly did. I did the Tech and General in rapid succession while just out of engineering school. The technical stuff, down cold as you might expect (at least hope) but I was smacked square in the face with operating. So I was all hat but no cattle despite passing both tests fairly easily without much studying (not aced mind you, in fact I got Tech by one or two above passing).

After using my license for a while I then took the Extra test a couple of years later, which is theory heavy but does require some detailed knowledge of operating and with what I'd learned in just a couple years of actually doing it in no small part was why that was 50/50.

There is *no* substitute for listening and keying the mic. You have no idea what you don't know or even what to ask until you start actually doing it.

As for the ARRL books, there's no great justification for getting the newest edition necessarily. They are edited and revised but the information changes slowly. So don't pass over one or two back, particularly the technical books. An 8th or 9th edition Antenna Handbook is more than sufficient, for example. The Operating and standard Handbook need to be a little newer to keep up with band allocations and rules, but the majority of information remains valid for several editions, still.

 

[Old_School]

Thank you that points me in the right direction of where to concentrate learning on haha. That being said, can we dive into for a moment the reasons why you say a 2m? I have been doing some reading and watching, and haven't quite found yet a 'good' site (well good in my mind anyway, OCD and picky I guess) that explains well the differences between other options as far as range goes, and how the wavelength transmission actually works within the atmosphere to be able to decide which one would be best suited for any given situation - which would dictate naturally where I start, since I want to learn with just one for now and then branch out.

AFTER I get my license - yes yes I know a license is needed.

Chorky, it sounds like the other posters have given you some good advice. To put it into even simpler terms though, think of 2m Ham, GMRS, MURS, and even CB, to mostly be line of sight (5-6 miles) when communicating mobile-to-mobile. If you have a repeater nearby, 2m can have a range of 20-50 miles (sometimes hundreds if repeaters are linked). 2m, GMRS, MURS, & CB are all good for trail riding with friends, as opposed to many of the Ham HF bands. The advantage of 2m Ham (145 mhz), GMRS (462 mhz), and MURS (150 mhz) is that they are FM, with very little interference from skip and atmospheric noise, etc. You'll generally only hear the squelch break when someone is calling you. I find that *very* convenient for trail riding, along with antennas that are generally less than 19" tall. With CB, you will tend to get a *bit* better range with full-size antennas (think 108" whips), as the signal will tend to follow the terrain out to 10-15 miles or so. However, many times there is so much static from skip and lightning crashes that you may not be able to talk more than 2-3 miles. Sometimes you can't talk at all.

I also run a Yaesu FT-857D HF/VHF/UHF rig in my truck, so I can theoretically transmit anywhere I can hear. However, for trail riding, I generally have a GMRS or MURS unit handy (FYI, MURS is another unlicensed radio service like CB & FRS that uses some of the old business band frequencies around 150 mhz. Radios are relatively inexpensive and you're allowed external antennas and 2 watts. It is composed of 5 set channels or frequencies, and I rarely ever hear anyone unless I'm near a Walmart, which still uses Ch. 4 & 5 of the old business freqs). Broadly speaking, VHF (2m & MURS) only needs 2-5 watts to achieve a 5 mile usable range.

Good luck on your quest.
Winston, N4WFB

 

[Chorky]

Tons of great info guys, thank you! This is getting super interesting!

Ok so, how about we switch gears and chat antennas for a few. So I've been doing more reading (and subsequently putting to the side studies for finals... oops ) and have now more questions. Isnt' that how it always is though? Guess that's why they call it tinkering hahah.

Ok, so reverting back to the GMRS (since that's where I'm going to start - it'll probably be toward the end of summer before getting the ham license), I found some diagrams and information explaining a little about antenna differences in terms of db gain. So for example, if I were to commit to the MXT400 mobile (which I have some doubts since it shows 'channels' and not frequencies), Midland offers their own antennas (3 kinds). One is quite small, and with no specs, so I would assume it's a 0db gain, another is a 3db gain, yet another is a 6db gain (and quite taller). I thought I started to have it figured out until the whole dbi and dbd got thrown into the picture. So, from my understanding, to keep it simplified, a low db gain allows for a shorter distance of reach but with a wider range of angles (think mountains), while a higher db gain would be just the opposite. Is this correct?

So, if one were to be in a variety of situations, then maybe a medium gain (say the 3db one) would be 'optimal'? To throw another curve ball in there...how does this relate to antenna height? So for example, of these three antennas (using them as an example since I'm sure there are 'better' ones out there), how does physical antenna height relate to quality, and distance? I ask because these antennas seem to be significantly smaller than I expected. So say for example that the antenna is on the roof, but also is a pair of kayaks - would one want to mount the antenna higher, or find a longer antenna to be above the kayaks for optimum quality?

This leads me to the CB antenna discussion. Now, I have a whip on my Jeep, and it works well. So for my truck I was considering a dual whip (let the hazing begin!! haha!). The reason being is I will frequently tow my trailer, and with the kayaks on top I would expect that if the antenna was mounted on one particular side, then the other side would be 'blocked' or with reduced signal strength, so a dual system would help prevent this. Now I am also aware that by doing dual antennas (at least for CB applications) that it causes the signal to be somewhat directional. But does anyone have any tested numbers, or an idea of specs of just how much this 'change' is? Also in relation to the db gain of a GMRS antenna? In other words, Midland states that a 6db gain antenna will reach 4x's as far, but what does that actually mean? Is that in terms of feet, miles, inches? And to what 'angle' is the signal reduced to? Are we talking a few degrees, or are we talking a 45 degree angle reduction (which would severely limit use in any hilly environment).? I'm a detailed person, and prefer actual specs when possible...

 

[Old_School]

Ok, so reverting back to the GMRS (since that's where I'm going to start - it'll probably be toward the end of summer before getting the ham license), I found some diagrams and information explaining a little about antenna differences in terms of db gain. So for example, if I were to commit to the MXT400 mobile (which I have some doubts since it shows 'channels' and not frequencies), Midland offers their own antennas (3 kinds). One is quite small, and with no specs, so I would assume it's a 0db gain, another is a 3db gain, yet another is a 6db gain (and quite taller). I thought I started to have it figured out until the whole dbi and dbd got thrown into the picture. So, from my understanding, to keep it simplified, a low db gain allows for a shorter distance of reach but with a wider range of angles (think mountains), while a higher db gain would be just the opposite. Is this correct?

Yes. With no gain, your signal looks something like a sphere or donut around your antenna. Easier to hit a repeater or another mobile on a mountaintop above you. Once you begin introducing gain, imagine that donut getting squashed. Signal is being pushed toward the horizon, at the expense of reaching higher elevations above and around you. The higher the gain, the flatter the signal. Higher gain antennas tend to work better in flatter terrain.

So, if one were to be in a variety of situations, then maybe a medium gain (say the 3db one) would be 'optimal'? To throw another curve ball in there...how does this relate to antenna height? So for example, of these three antennas (using them as an example since I'm sure there are 'better' ones out there), how does physical antenna height relate to quality, and distance? I ask because these antennas seem to be significantly smaller than I expected. So say for example that the antenna is on the roof, but also is a pair of kayaks - would one want to mount the antenna higher, or find a longer antenna to be above the kayaks for optimum quality?

It won't really matter at UHF frequencies, although generally speaking, the higher the antenna, the farther you can talk. If you're talking about ABS or rotomolded kayaks, they won't significantly affect your signal. The shorter antenna stands a lesser chance of being damaged when you bump it with the kayaks.

This leads me to the CB antenna discussion. Now, I have a whip on my Jeep, and it works well. So for my truck I was considering a dual whip (let the hazing begin!! haha!). The reason being is I will frequently tow my trailer, and with the kayaks on top I would expect that if the antenna was mounted on one particular side, then the other side would be 'blocked' or with reduced signal strength, so a dual system would help prevent this.

Don't even go there. UHF (GMRS) radio waves will be bouncing all over the place, negating any potential gain you might see (and I doubt it would be measurable). I've never heard of anyone co-phasing VHF or UHF antennas, except for many element beam (home) antennas for satellite work. You'll never see a difference. Also, unless your CB antennas are at least 1/4 wavelength apart (~9'), you won't see a difference on your CB, either.

 

[Chorky]

Ok, so now how do different antennas, different gains, etc.. affect power output and needing to stay within regulations, or reducing the resistance to prevent radio transmitter damage? And how does this get compounded with a non-conductive mounting surface such as an aluminum or fiberglass canopy? I know there are no-ground plane antennas, but they seem to reduce overall performance as I understand it, so what about just running some grounding wire?

Also, there are multiple antennas that I have found that say they are 'cut to length' to get them to the band that is desired (which seems odd), so aside from SWR meters, power output, and return reflective power (which this makes me need to research more since I'm lost again), what other factors need to be calculated to make sure I am getting the best performance without causing any damage to my radio system, or exceeding FCC regs.?

 

[Old_School]

Ok, so now how do different antennas, different gains, etc.. affect power output and needing to stay within regulations, or reducing the resistance to prevent radio transmitter damage? And how does this get compounded with a non-conductive mounting surface such as an aluminum or fiberglass canopy? I know there are no-ground plane antennas, but they seem to reduce overall performance as I understand it, so what about just running some grounding wire?

The antennas don't affect radio output. Aluminum can serve as a ground plane, fiberglass cannot. Grounding wire won't work. One way to achieve an effective ground plane on a nonconductive surface is to mount a suitably-sized metal plate beneath your body mounting point. It can also be done with adhesive copper foil, electrically bonded to the base of the antenna.

Also, there are multiple antennas that I have found that say they are 'cut to length' to get them to the band that is desired (which seems odd), so aside from SWR meters, power output, and return reflective power (which this makes me need to research more since I'm lost again), what other factors need to be calculated to make sure I am getting the best performance without causing any damage to my radio system, or exceeding FCC regs.?

You'll need someone to help you with an SWR meter if you have an antenna that needs to be trimmed to frequency. This stuff is not that complicated. Buy yourself an ARRL study book and take your Ham test and much of this will be covered.

 

[Chorky]

The antennas don't affect radio output. Aluminum can serve as a ground plane, fiberglass cannot. Grounding wire won't work. One way to achieve an effective ground plane on a nonconductive surface is to mount a suitably-sized metal plate beneath your body mounting point. It can also be done with adhesive copper foil, electrically bonded to the base of the antenna.

Ahh interesting. I was thinking about that but wasn't sure if it would be appropriate. But if your talking fiberglass then doesnt that metal plate have to be grounded to the frame?

You'll need someone to help you with an SWR meter if you have an antenna that needs to be trimmed to frequency. This stuff is not that complicated. Buy yourself an ARRL study book and take your Ham test and much of this will be covered.

Yeah planning on picking one up in a few weeks when finals are over. Haha just keep getting distracted with researching all this.

 

[BigSwede]

I use a half-wave antenna on my FJC as the door hinge mount is iffy for ground plane.

 

[sonoronos]

So, if one were to be in a variety of situations, then maybe a medium gain (say the 3db one) would be 'optimal'?

There is no such thing as "optimal". There are only compromises. In your head, you think "What one antenna should I get that is best for what I want to do". The truth is, there is no best.

Some people run antenna switches and run multiple antennas with different patterns.

how does physical antenna height relate to quality, and distance?

Quality is a measure of antenna bandwidth (Q-Factor) and has nothing to do with height. The higher you mount your antenna, the better range they get.

Antennas are not wristwatches. You don't "buy the best". They are just implementations of physics. If by "height" you mean "length", read about antenna length vs. frequency. In general a random wire antenna with the appropriate tuning load will have varying Q-factors depending on length.

But does anyone have any tested numbers, or an idea of specs of just how much this 'change' is? Also in relation to the db gain of a GMRS antenna? In other words, Midland states that a 6db gain antenna will reach 4x's as far, but what does that actually mean?

Buy yourself an antenna analyzer and do the metrology yourself. No-one on the internet can answer this for you.

3dB = 2x ERP. 6db = 4x ERP. 4xERP is NOT 4x range.

 

[sonoronos]

Ahh interesting. I was thinking about that but wasn't sure if it would be appropriate. But if your talking fiberglass then doesnt that metal plate have to be grounded to the frame?

You can use radial counterpoises on fiberglass roofs. You don't need a totally metal surface as a ground plane. Base loaded antennas can solve the ground plane issue. If you're running VHF or UHF, half-wave monopoles solve most of your problems.

You do not need to ground to the frame. "Ground Plane" is not what you think it is.

 

[Old_School]

There is no such thing as "optimal". There are only compromises. In your head, you think "What one antenna should I get that is best for what I want to do". The truth is, there is no best.

Some people run antenna switches and run multiple antennas with different patterns.



Quality is a measure of antenna bandwidth (Q-Factor) and has nothing to do with height. The higher you mount your antenna, the better range they get.

Antennas are not wristwatches. You don't "buy the best". They are just implementations of physics. If by "height" you mean "length", read about antenna length vs. frequency. In general a random wire antenna with the appropriate tuning load will have varying Q-factors depending on length.



Buy yourself an antenna analyzer and do the metrology yourself. No-one on the internet can answer this for you.

3dB = 2x ERP. 6db = 4x ERP. 4xERP is NOT 4x range.

Well said.