Radio Mobile is a free tool created by VE2DBE that can be used to predict radio wave propagations and plot them on maps. Radio Mobile uses basic topographical data combined with some vegetation clutter data to predict radio wave propagation. Some skill is required to generate accurate predictions, but using this guide will get you pretty close.
Introduction
Essentially what this tool allows you to do is create two “imaginary” radio stations, and calculate which places these two stations will be able to send/receive signals between each other.
For example, lets say that station (A) is a base radio with an external antenna at your house, and station (B) is a mobile (vehicle) radio. Radio Mobile will let you generate a map overlay that visually projects where (A) and (B) will be able to talk to each other.
The settings used in this guide are the exact settings that were previously used to generate coverage models for repeaters in the Arkansas GMRS Repeater Group, and are at least somewhat “verified” to be accurate.
Radio Mobile uses very basic terrain & vegetation clutter data. It does not use any data for buildings or structures. Densely urban propagations will not be accurate. Vegetation data may be out of date. There are more accurate professional & commercial tools, but Radio Mobile is widely recognized as one of the best free propagation prediction tools available.
It is very easy to generate a coverage prediction that far exceeds how the system would perform in real life. If you are estimating or do not know the exact value for a given field, try to be conservative with your estimations. When in doubt, estimate the system to be worse than you expect, so you do not end up with an over-confident coverage prediction.
Wait for the calculation to finish (it might take a while)
Browse the predicted coverage map. Click Add to my coverages to save this calculation for later viewing.
One of the first questions you will find yourself asking after getting your GMRS license is “What radio should I buy?” Although there is no single answer to this question, this article will aid you in your research.
Base Station: a radio used in a stationary place such as your home or office. This radio is usually connected to a larger, outdoor antenna and can be used with or independently of a repeater within its coverage area. This will give you great coverage from your home “base”.
Mobile Station: radios usually installed in vehicles. Radio is usually 10-50 Watts output and uses the battery supply of the vehicle and an antenna mounted to the vehicle by either a magnet, hole drilled, or other bracket. Most of these types of radios can also be used as a base station with the addition of a power supply.
Portable Station; handheld radios designed to be carried on the person. This is the most common radio GMRS licensees start out with. Sometimes called an “HT” (handheld transceiver), “walkie-talkie”, or “portable”. These radios are self-contained and very convenient. They are for short range communications and only operate at a fraction of the performance of a mobile or base station (defined above). They operate poorly inside of vehicles, enclosed buildings, and have inefficient antennas.
For communicating with any other station or repeater that is more than a couple of miles away from you.
Portable
For communicating with any other station or repeater that is less than a couple of miles away from you.
Why do we say that your portable GMRS radio, which advertises a 50 mile range on it’s packaging, is only good for a couple of miles or less?
Advertised ranges are based on perfect laboratory conditions, and are not to be expected in the real world. We say that a portable radio is “for communicating with any other station or repeater that is less than a couple of miles away from you”, because you can expect this range reliably. Portable GMRS radios are not actually limited to communications distances of only a couple of miles or less. In reality, radio range depends on several variables. Although rare, it is possible for a portable GMRS radio to make successful communications across distances of 100 miles or more if the atmospheric and terrain conditions are just right.
What are the requirements for a GMRS compatible radio?
These are absolute bare-minimum requirements in order for your radio to support GMRS.
Analog Voice: the radio must be able to transmit and receive analog voice audio communications
462MHz-467MHz: the radio must support frequencies in the 462MHz-467MHz UHF (ultra-high frequency) range. VHF (Very High Frequency) radios will not work for GMRS.
25KHz Bandwidth: the radio must support 25KHz bandwidth, also known as “wideband”. Narrowband only radios should be avoided. Some radios labeled as “GMRS radios” do not actually support wideband (Midland MXT105, MXT115, MXT275) making this difficult.
Repeater Capable: although not technically a requirement to be a GMRS radio, it is important to note that not all GMRS radios are repeater capable. For example, most GMRS handheld radios sold in big-box stores are not repeater capable.
The FRS/GMRS handheld radios commonly sold in stores are not repeater capable and cannot be re-programmed.
What brands should I look for?
While we will try to aid in your search for reliable radios, it is important to note that this information is subjective and is the shared opinion of several experienced repeater owners in the Arkansas GMRS Repeater Group.
Commercial Grade Radios
It is important to note that GMRS was originally a commercial / business radio service before the FCC opened it up to individuals and families. Since the opening of GMRS, most commercial services and businesses have replaced their old GMRS compatible equipment with modern digital radio technology.
Due to these recent changes in GMRS and radio technologies, there is a large surplus of commercial grade GMRS-compatible radios available on the used market (e.g. eBay, FB Marketplace, Mercari) from highly reputable manufacturers such as Kenwood and Motorola. Although typically pre-owned, these radios are extremely high quality and dependable.
The #1 downside to commercial grade radios is programming them. Often, it is required to obtain specialized cables and computer software in order to program and change the settings of commercial radios – whereas consumer grade radios can usually be programmed on-the-fly via the radios built-in buttons.
Another downside to commercial radios is that they are extremely basic in nature. They were designed to be programmed once, and then used by anyone in the fleet whether or not they had any previous knowledge of radio operation – “just pick up the mic and talk!” Commercial radios often lack “extra” features seen in modern consumer radios such as out-of-band scanning, weather alert radio receiver, FM radio receiver, etc.
Pros:
High quality
Usually inexpensive
Cons:
Inconvenient programming
Less “extra” features
Commercial Grade Radio Brands
Kenwood
Motorola
Maxon
Vertex Standard
Standard Horizon
Icom
Hytera
EF Johnson
If you are a member of a GMRS club or group such as the Arkansas GMRS Repeater Group, then you likely already have access to the programming cable and software for any commercial radio you can find through your fellow members and repeater owners. Just ask!
Consumer Grade Radios
With the sudden rise in popularity of GMRS, the consumer market has recently been flooded with low-quality transceivers making it difficult to find something worthy of your hard-earned money. It is the opinion of the author of this article and several experienced repeater owners that most all of the following brands & radios are significantly overpriced and of much lower quality than the commercial grade options listed above. Most of these brands sell the same radios, just under different labels.
Of the consumer brands available, Midland and Wouxon are highly rated by GMRS licensees and are the only recommended brands.
Pros:
Easy programming
Extra features
Cons:
Lower quality
More expensive
When looking for mobile radios, it is recommended to consider the commercial grade radios listed previously, which can usually be obtained for less than half the price of a new Midland or Wouxon mobile unit.
Midland
Midland sells radios that are specifically designed for GMRS and are extremely easy to use. They come pre-programmed with GMRS channels and require little to no setup in order to use. They do not need a computer to be programmed.
Beware of these Midland models that are narrowband only and do not support wideband operation. These should not be used for GMRS. MXT105, MXT115, MXT275.
Wouxon
Wouxon also sells pre-programmed GMRS radios. These radios offer more “extra” features which makes them less intuitive to operate than Midland radios. They are not required to be PC programmed, but they do support it. Wouxon handhelds and mobiles have superheterodyne receivers which offer significantly higher reception performance than other consumer brands.
Not Recommended
These radio brands are not recommended as they are known for one or more of the following: high price, low value, poor audio quality, difficult to hear audio, and/or poor performance.
Numerous of these low-quality consumer brands exist with more and more popping up over time:
Baofeng
BTECH
Tidradio
Radioddity
TYT
Retevis
Aliunce
AnyTone
Quansheng
and more…
Examples of GMRS Compatible Radios
These tables contain some examples of Part 95 (GMRS) accepted & repeater compatible radios to aid you in your search. These lists are not exhaustive.
Please be aware that the prices listed in these tables are either estimates or MSRP obtained at the time this article was written, and will likely change drastically over time.
Commercial Radios
Type
Manufacturer
Model
TX Power
Approx. Price
Mobile
Kenwood
NX-800H
45W
$200
Mobile
Kenwood
TK-8180HK
45W
$75
Mobile
Kenwood
TK-860HG
40W
$40
Mobile
Kenwood
TK-880H
40W
$50
Mobile
Kenwood
TK-8180K
30W
$75
Mobile
Kenwood
TK-860G
25W
$60
Mobile
Kenwood
TK-880
25W
$40
Mobile
Motorola
M1225
45W
$75
Mobile
Vertex (Yaesu)
VX-5500
50W
$130
Mobile
Vertex (Yaesu)
VX-4200
45W
$150
Mobile
Vertex (Yaesu)
VX-3200
40W
$60
Mobile
Vertex (Yaesu)
VX-2500
25W
$75
Portable
Icom
F40GT-2
4W
$190
Portable
Kenwood
TK-370
4W
$30
Portable
Kenwood
TK-380
4W
$30
Portable
Kenwood
TK-390
4W
$50
Portable
Ritron
RTX450
6W
$40
Note: Some commercial radio brands/models might require additional work to get programmed – more than just a cable purchase and a software download. One example of this includes the Motorola XPR series, which officially requires a unique code called an “entitlement key” to be purchased from Motorola and entered into the programming software before programming of wideband channels are allowed.
You can have the best radio in the world, but it doesn’t mean anything if it doesn’t have a useful antenna on it.
Let’s say you are new to GMRS and all you have is a handheld (HT) radio. Immediately what most do is to try to figure out the range of their signal. They may be able to go a couple miles, but soon they realize that they aren’t using the full extent of their license and making the most of their radio system. They might look to improve- and that’s what this article is for.
The antenna summarized in a word would be COMPROMISE. It’s a compromise among a number of considerations, such as budget and spousal approval. Nevertheless the best improvement one can make to their station today – as a HT user – and tomorrow as a proper 50 watt repeater and 200′ tower – is to improve what antenna they use.
The concept is pretty simple. An antenna put out energy (it “radiates”) in almost all directions. In fact the ideal antenna radiates energy in all direction, but as you can imagine such an antenna exists only in text books. Here you can see the source being the red dot in the middle, and the wire mesh is the radiated power. If this is a bit confusing, just hang in there.
The most iconic antenna is the Dipole. It is a fundamental building block to other designs. A Dipole is 1/2 wavelength long, which at GMRS Frequencies is about 12 inches. This is what it’s pattern looks like:
You can see the radiation pattern in the bright red ring. It very much looks like a donut shape. The dipole would run through the hole of the donut. You’ll also see two cross sectional pictures – the Elevation and the Azimuth.
You can see now that we went from a perfect sphere to a donut. This squashing and changing of the antenna radiation pattern is what makes or breaks an antenna. It’s also why there are so many weird and odd designs for antennas. Here’s a comparison of the two if we overlay a cross sectional look:
You can see where the green gets “smushed” down to make it go more out horizontally. For us this is a good thing. Usually the people or repeaters we want to talk to are at the horizon. There are other antenna designs that smash this even flatter, which we will look at shortly.
The dipole is also known as a “1/2 wave antenna” if you look up a mobile version. Many times mobile stations will use 1/4wave antennas. The patterns are similar as electrically with a ground plane of a car, they work much like a dipole.
~Which brings up a good point, without enough ground plane for an antenna to “work” against, you are essentially cutting your antenna in half.~
So with this idea of smashing down the donut, you can even make it flatter into a pancake. So unless I’ve lost you, you can make your power go from a ball to a donut to a pancake. You can even “stack” these antennas, which is to say put more together. For example, the go to common repeater class antenna is the DB420 antenna, made by Decibel (or who ever owns it this week). This antenna has 16 dipoles mounted on a 20 foot long pole with a gain of 11.3dBi (dBi means the number of dB over an isotropic antenna) this means you signal is ~15.2 times as powerful out on the horizon then our simple little perfect ball. It also means that it is ~9.15dBd (dBd means the number of dB over a dipole, the only practical reference antenna). In these terms, that means that the signal is about 8.5 times stronger at the horizon than the dipole.
So let’s step back and think about this for a minute. Let’s say I’m running 5 watts into a DB420 repeater antenna (we’ll just ignore feedline loss, that’s for another article.) In order to get that same radiated power (i.e. coverage, distance, etc.) while using a dipole, you would have to transmit 42.5 Watts.
This isn’t magic or free energy. This is just moving around the part of the radiated signal into a more useful direction.
In the next article of Antennas for All we are going to move away from theory and talk more about choosing which to build or buy.
The General Mobile Radio Service is a radio service that favors mobile radios.
Almost every users first GMRS radio is of the handheld or “portable” variety. There is absolutely nothing wrong with this! Handheld radios can be extremely affordable, easy to use, and just make sense for a lot of GMRS licensees – but there are some things you should know about handheld / portable radios in the context of GMRS repeaters.
Why do they suck?
GMRS is an acronym for General Mobile Radio Service. In this context, a “mobile” station typically comprises a high-powered radio (10-50 watts) and an externally mounted antenna (roof, trunk, etc), installed on a moving vehicle like a car, truck, tractor, or ATV. These mobile installations will always drastically outperform handheld stations for a few reasons:
Low-Quality Radios: While not always the case, the GMRS market is flooded with low-quality handheld radios. Merely being labeled as “mobile” doesn’t inherently make a radio superior, but generally, they do tend to have more sensitive receivers, better audio quality, etc.
Power: While transmit power isn’t the sole factor, having more than double the power of a handheld radio can enhance signal transmission through obstacles, atmospheric conditions, and noise.
Antenna Location: Portable GMRS radios will not perform inside of a vehicle without connecting them to an externally mounted antenna. The body of the vehicle acts like a faraday cage blocking most radio signals. Given that you need an external antenna anyways, go ahead and hook a better radio up to it!
Antenna Size: Larger mobile stations allow for physically larger antennas. Handheld radios sacrifice antenna efficiency for portability.
Antenna Height: While your car’s roof may not be significantly taller than you, raising the antenna can increase signal strength, similar to holding your cell phone higher to get better reception.
Antenna Polarization: Antennas must be oriented the same way as the transmitting or receiving antenna for optimal signal exchange. Mounting an antenna on a vehicle ensures it’s positioned straight up and down, whereas handheld radios are prone to being moved around and held at an angle, affecting performance due to improper orientation.
Antenna Ground Plane: Installing a large metal surface beneath the antenna creates a “ground plane”, acting as a reflector that aids RF signal interaction. Handheld radios rely on the person holding the radio as a ground plane, which is less efficient compared to the roof of a vehicle.
Portable GMRS radios are good candidates for short-range communications – only a few miles.
Repeater Coverage Comparison
Here is a visual example using the estimated coverage of one of our flagship wide-area repeaters, NWA700. Drag the slider back & forth to see the difference between coverage when using a portable vs. mobile radio. Simply using a mobile station increases the calculated usable coverage area by 265% (nearly 4x the range).
Northwest Arkansas 700 Repeater – Handheld vs. Mobile Coverage
Why should I care?
Handheld radios are great for short-range group communications in scenarios such as small events, camping, hiking, hunting, and more where a lightweight & convenient transceiver is needed. In the context of the Arkansas GMRS Repeater Group – a lot of users interested in repeaters tend to want to “range test” or see “how far they can talk”. Combined with the popularity of affordable portable GMRS radios, it’s no surprise that significant amounts of repeater traffic come from underpowered portable radios that are too just far away from the repeater for reliable communications.
If you’re looking to use GMRS for distances over a few miles, or reach a repeater from over a few miles away, you need a mobile or base station!
What mobile or base radio should I buy?
Great question! Although the consumer GMRS market is saturated with low-quality radios from overseas (Midland, Rugged Radios, Baofeng, Tidradio, Radioddity, Pofung, etc), some are ok – YMMV. Used commercial radios like Motorola and Kenwood are almost always cheaper and significantly higher quality than any “new” radio on the market.
