Watts Uhf
Watts Uhf
 |
No items matching your keywords were found.
|
|
POWER / SWR METER CB Radio 100 Watts w/ 3' Jumper cable - Workman SWR3P & CX-3-PL-PL $19.95 ... |
|
|
Midland 18-258 40-Channel Glass-Mount CB Antenna $10.98 This 40-Channel CB Antenna from Midland is made for mounting on any vehicle, and works with all CB radios, Midland and otherwise. 27 MHz Antenna This 27 MHz antenna is ideal for receiving CB, VHF weather and hazard broadcasts, offering 40 channels and capable of handling a 10-watt maximum. Simple Window Mount Installation is a breeze with this antenna. It's ideal for placement on glass, with... |
|
|
Yaesu FT-2900R 75 Watt 2 Meter VHF Mobile Transceiver Amateur Ham Radio $198.80 Mobile two meter Amateur Ham radio 75 Watt transceiver. Features lighted microphone with direct entry keypad, ctcss & dcs, scan & search modes. Transmits the 144-148Mhz Amateur radio band, receives 136-174Mhz.... |
|
|
ROBBIE LONG & DEVASTATE / LEE UHF / 50,000 WATTS / DUBSTOMP TWO CRACKING TRACKS... |
|
|
Coaxial Lightning Antenna Surge Protector for Amateur, Ham, CB & Two-Way Radio - LP-350 $29.99 Inline Coaxial lightning surge Protector installs inline with Coax antenna cable of Ham Radios, CB, commercial & two way radio antennas. For Transceivers up to 350W, 0-600Mhz. SO-239 connectors.... |
|
|
Kenwood TK3230K 2 Channel UHF Hand Held Radio $163.99 The Kenwood ProTalk TK-3230 Two-Way UHF Radio is just what you need if you are at a work site, handling hospitality, or a contractor who needs to be constantly in touch with his workers. This reliable and easy-to-use radio delivers just what it promises - first-rate, two-channel UHF capability. The 56 programmable pre-stored frequencies give you enough leeway to converse without interference. Thi... |
|
|
Power Pro Powered Companion Speaker Reach an even larger audience with Califone's PowerPro Companion Speaker. This wireless speaker projects clear sound to groups of up to 1,000 people. Features a 16-channel wireless mic receiver and a circuit that allows you to connect it to two additional units. Also includes independent bass and treble control, digital master volume control, power status indicator and a universal power supply.... |
|
|
Motorola MR350R 35-Mile Range 22-Channel FRS/GMRS Two-Way Radio (Pair) $50.70 The Motorola Talkabout MR350, with its range of up to 35 miles and bundle of great features, is a great communication tool for the serious outdoor enthusiast. Lightweight and rugged, with extra large buttons to help you operate even with gloves on, the MR350 is built to handle any challenge without weighing you down. The MR350 includes an emergency alert feature, to inform others should any danger... |
|
|
Midland GXT760VP4 36-Mile 42-Channel FRS/GMRS Two-Way Radio (Pair) $38.99 The Midland GXT760VP4 are 42 Channel GMRS Radios with NOAA Weather/All Hazard Alert. Includes DC Adapter, Headsets, Rechargeable Batteries, Dual Desktop Charger, and are packed in pairs. The GXT760VP4 features the standard 22 GMRS Channels with an extra 20 Channels and a range of up to 36 Miles. The Weather Scan feature finds the nearest NOAA broadcast to stay up to date with the latest weather an... |
|
|
Midland XT511 22-Channel FRS/GMRS Two-Way Emergency Crank Radio $89.99 Midland's XT511 is a durable GMRS emergency crank radio with a wealth of features to keep you informed, charged up, and in contact no matter the situation around you. Stay in touch no matter your environment. Dynamo crank allows recharging of batteries without access to electricity. Built-in flashlight and USB port for charging your cell phone or other device... |
|
|
Build Your Own Low-Power Transmitters: Projects for the Electronics Experimenter $42.11 Rudolf Graf and William Sheets have written a book containing twenty low-power (LP) transmitter projects, perfect for the electronics hobbyist and radio experimenter. Now that the FCC has changed its regulations about "pirate" transmissions, more and more people are setting up radio and video stations for broadcast from their homes. Build Your Own Low-Power Transmitters addresses applications for ... |
Why is not more?!prove to me with mathematics calculations please?
Why is not range of handheld two-way radio 4 watt HF band(26 mhz) more than range of handheld two-way radio 4 watt UHF band (440MHZ) in big city areas?
It is not that clear cut. If you look at the link for path loss below, it appears frequency dependant, and that is because of the aperture of the antenna. Basically the antenna is smaller at high frequencies. This can be overcome to some degree by using a bigger more efficient antenna at higher frequencies.
Radio waves travel in straight lines, and 26 MHz and 440 MHz are more or less the same in that way. Medium frequencies may follow the earths surface, and may be propagated long distances using the ionosphere, as are HF frequencies. Frequencies like 26 MHz may occasionally be able to travel distances by reflection off the ionosphere, but not often. It is in a transition area between HF and VHF. Even 440 MHz occasionally travels far in ducts and other such propagation modes, but less often still off the ionosphere..
If there does happen to be an ionospheric path for 26 MHz we need to consider the take off angle of the antenna at each end, and skip zones as well. Often the signal must be at a relatively low angle so it can be reflected, rather than passing straight through the ionoshere. This means there is a region where the direct signal is no longer available, but the ionospheric signal does not reflect back to earth because the angle is too steep. Further away the ionosheric signal appears. This is the skip zone.
For line of sight we have a simple calculation of path loss, receiver sensitivity and transmitter power and antenna gains. Actually in a city these two bands will be absorbed and scattered and reflected and refracted in slightly different ways, but not much different. The lower frequency is particularly less likely to enter buildings as strongly (through holes like windows).
There are a couple of other things that occur. A radio wave travelling over the earth or sea bends due to the humidity gradient, so actually goes a little over the horizon, or maybe a little less than the horizon. A radio wave travelling close to the earth's surface will have components reflected back from the earth to interfere with the direct ray (in and out of phase). These cause fading in VHF and microwave systems.