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  • Radio Range and Expectations

Radio Range and Expectations:

When choosing a radio or radio system it is important to understand what it can and cannot achieve. If you've never used portable or mobile Two-Way radios before and are new to this form of communications please read below to better understand what to expect. Many people new to Two-Way radios have expectations which can exceed what is physically possible with the equipment they have purchased or intend to purchase. Here is some good advice and rules of thumb from years of practical experience.

VHF frequencies (approx. 148-174 MHz)
Best for outdoor use and around residential areas. The VHF range is used widely by Police, Fire and EMS services in smaller cities and municipalities. Truck dispatch and businesses that need to communicate with mobile personnel in the 10 to 25 mile range from a base station. It is also used for Coast Guard & Marine communications.
   This band is also the most popular with persons who work or play outdoors. Park rangers, wildlife researchers, logging operations, campers, hikers and hunters favor VHF for its characteristic of being able to travel around rolling hills, moderate terrain and vegetation. Using VHF portables or mobiles with a Repeater can substantially increase range and performance.

Basic VHF Properties:

  1. Good outdoor, residential and rural area performance
  2. Complex terrain and obstacle handling
  3. Portable to Portable Range:
    • 1/4 to 5 Miles depending on transmit power, antenna type and structures/obstacles/terrain.
  4. Mobile to Portable Range:
    • 2 to 10+ Miles depending on transmit power, antenna type and structures/obstacles/terrain.
  5. Use with Repeater Range:
    • up to 25+ Miles depending on transmit power, antenna types and structures/obstacles/terrain.


UHF frequencies (approx. 450-512 MHz)
Ideal for indoor use and around buildings of reinforced concrete and steel. UHF is also a good choice for multi-level buildings and is the first choice of Police, Fire and EMS service in large cities and metropolitan areas.
   Commonly UHF band radios are used with a Repeater. A Repeater is a special type of radio that receives on one frequency and transmits on another frequency simultaneously. They are usually installed in high clear locations (mountain tops, high buildings or towers) and greatly increase the range of all radios programmed to use them.
   This band is most popular with Police, Fire, EMS, building maintenance services, security, Colleges, Universities and almost anyone who works around large man-made structures, technical and industrial centers or in densely populated areas. UHF band signals seem to possess a greater ability to penetrate and travel/reflect around concrete and metal structures and its antenna types tend to be smaller and more convenient for use on portables and in limited space applications.
   UHF is also good for outdoor use but tends to give slightly less range since it is more easily absorbed by vegetation. Also, rugged terrain can cause problems since UHF signals do not "bend" or propagate around large solid objects well, having a greater tendency to bounce or reflect and become blocked by terrain.

Basic UHF Properties:

  1. Good indoor and city performance
  2. Metal and Concrete structure handling
  3. Portable to Portable Range:
    • 1/4 to 5 Miles depending on transmit power, antenna type and structures/obstacles/terrain.
  4. Mobile to Portable Range:
    • 2 to 10 Miles depending on structures/obstacles/terrain.
  5. Use with Repeater Range:
    • up to 25+ Miles depending on transmit power, antenna types and structures/obstacles/terrain.

Portable Handheld Radios - The higher the power, the farther you communicate. Select radios that give you the range you need and match your budget. Usually the more power the better but a full 5 watt portable may not be necessary if you are operating your radios in a small, relatively close group. Best range results are obtained in "line-of-sight" situations such as over water, mountain top to mountain top or on an open field or beach. Range is adversely effected by terrain and geography, vegetation, obstacles, structures and environmental conditions. Range can vary greatly depending on all these factors and the above chart should be considered "rule-of-thumb" under best case conditions only.

Using a portable with a repeater system increases the range dramatically. This is because now you are operating portable to repeater to portable. This can multiply portable to portable range by a factor of up to 5 or more. With a quality high mountain top repeater ranges of 50+ miles are possible under good conditions.

Mobile and Base Station Radios - The higher the power the better with mobile or base station radios since you are not limited by the power in a portable's battery pack and normally have an unlimited power source available from your vehicle or building. Mobile and Base Station transmit power available varies from 25 to 100+ watts and lower power mobiles/bases can always be boosted with separate amplifiers if needed. Generally the standard power output necessary for good mobile/base operation is 25 to 50 watts. This power level is adequate for most situations. Power levels above 50 watts should be used in very tough urban environments and where high penetration of structures is needed or in rural areas where greatest possible range is required. The addition of gain type mobile and base station antennas can also greatly improve range and penetration at a quite reasonable cost compared to standard 1/4 wave unity gain antennas.

Using a mobile with a repeater system enhances range and reliability. This is because now you are operating mobile to repeater to mobile. This can multiply mobile to mobile range by a huge factor. With a quality high mountain top repeater ranges of up to 50-100 miles can be achieved under good conditions.

 

Repeater (do I need one?)
A repeater is a piece of equipment designed specifically to increase the portable to portable or mobile to mobile range of a radio system. It is a special type of radio that receives on one frequency and transmits on another frequency simultaneously. A repeater instantaneously re-transmits or "repeats" the signal it hears in its receiver on a different frequency with its own built-in heavy duty transmitter. They are usually installed in high, clear locations (mountain tops, high buildings or towers) and greatly increase the range of all radios programmed to use them.
Repeaters are used extensively by Police and Fire departments, EMS systems and private companies to maximize the range and reliability of their systems coverage area. Depending on what range performance you expect from your radios a repeater may or may not be necessary. Most outdoor activities such as hiking, hunting and camping do not require a repeater since the range needed is not that great and the expense and fixed position of a repeater would make it impractical. Smaller business and municipal operations usually can operate well without a repeater if a properly installed base station is used. Large municipalities, universities, hospitals, construction sites and businesses can benefit greatly from the increased unit to unit performance that a properly installed and maintained repeater can afford.
There are several requirements for a repeater system to work properly and efficiently:

  1. Licensing a repeater frequency "pair" via the FCC. There are many companies who will do the legwork and considerable paperwork to obtain a FCC licensed frequency pair on which your repeater can operate. If you type "FCC licensing" in any of the major search engines you can easily find a company that will help you.

  2. Finding a location for your repeater. This can sometimes be the most difficult part of the process. A clean, dry and secure location that has a good source of AC power is a must. Even more important is the elevation of the antenna you intent to use. A general rule of thumb is that your repeater antenna should be at least 300 feet (100 meters) above the average terrain if you want to obtain good performance.

  3. Obtaining a single, high quality antenna with as much gain as required. Using a single antenna with which to receive and transmit simultaneously is the best and most efficient method of operating a repeater. This requires the use of a duplexer which increases overall cost (see item # 4). Two separate antennas (one for receive and one for transmit) can be used but this complicates the setup and operation of the repeater. Two antennas can also significantly degrade performance due to receiver de-sensing from the transmitter antenna.

  4. Obtaining a duplexer for single antenna use. A duplexer is a highly specialized device designed to allow a single antenna to be used for high power transmitting (on the transmit channel of the frequency pair) while at the same time extremely weak micro-volt range signal reception (on the receive channel of the frequency pair). Duplexers require precise tuning by specialized equipment which is usually done at the manufacturer or factory when a new repeater is initially set up. A duplexer is designed and tuned to operate on one frequency pair only. When using a multi-channel repeater with a duplexer you must remain on the channel that is programmed to match the duplexers frequency pair or severe damage to the repeater can result.

  5. Obtaining high quality cable and connectors for your antenna system. Typical coax cable is useless for a repeater antenna system. Special hard line type cable with the proper low loss connectors is an absolute must if the system is to work successfully.

  6. Proper physical installation. Professional antenna mounting, connector installation and waterproofing, cable harnessing/routing and system grounding to local code is essential. Lightning protection on the antenna system and AC power supply is also extremely important since even a nearby lightning strike can put your repeater out of service.

Carefully considering all the above requirements is important before investing in a repeater system. Obtaining all the necessary component parts, licensing, location, antenna system and specialized setup and installation can be time consuming and expensive but the benefits are great. Often times a properly installed repeater system can give many years of almost maintenance free operation. Vastly improved range, building penetration and reliable system operation can be well worth the time and expense.

 

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NOTE: Features, prices and specifications subject to change without notice. Not responsible for typographical or technical errors, information presented is for general evaluation only.

Radio Range and Expectations

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