.net barcode reader free Antennas for emergency operations 487 in Software

Maker Data Matrix ECC200 in Software Antennas for emergency operations 487

Antennas for emergency operations 487
Scan Data Matrix 2d Barcode In None
Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications.
Data Matrix ECC200 Printer In None
Using Barcode encoder for Software Control to generate, create Data Matrix 2d barcode image in Software applications.
Less than
Scan Data Matrix In None
Using Barcode decoder for Software Control to read, scan read, scan image in Software applications.
Paint ECC200 In C#
Using Barcode printer for VS .NET Control to generate, create DataMatrix image in .NET framework applications.
Antenna tuner
DataMatrix Maker In .NET Framework
Using Barcode creation for ASP.NET Control to generate, create Data Matrix ECC200 image in ASP.NET applications.
Painting ECC200 In .NET Framework
Using Barcode printer for .NET Control to generate, create Data Matrix 2d barcode image in .NET applications.
Transmitter
Data Matrix ECC200 Maker In VB.NET
Using Barcode creator for Visual Studio .NET Control to generate, create Data Matrix 2d barcode image in VS .NET applications.
Code 3/9 Creation In None
Using Barcode maker for Software Control to generate, create USS Code 39 image in Software applications.
25-4 Basic mobile antenna system often proves unsatisfactory in marginal cases
Printing EAN-13 Supplement 5 In None
Using Barcode drawer for Software Control to generate, create EAN13 image in Software applications.
Code 128 Code Set C Printer In None
Using Barcode printer for Software Control to generate, create Code 128 Code Set C image in Software applications.
operator We can make a basic assumption for these improvements: The operator needing emergency or urgent communications is not driving down the interstate somewhere, but is stopped in the back country and needs to call out In cases of emergencies on most highways, we are in range of some repeater, so we would use a VHF band (probably 2 m) to contact police or other emergency services through a repeater autopatch In fact, with the wide availability of repeaters around the country it behooves any amateur, backpacking or four-wheeling into remote areas, to be familiar with repeater locations and frequencies From hilltops, especially, it is often possible to hit repeaters from a surprisingly long distance I have seen hand-held 2-m rigs trigger mountain top repeaters from the mountains of southwestern Virginia, and presume that other areas of the country are as well off repeaterwise This chapter deals with HF rigs, especially those operating in the lower end of the HF spectrum, in situations where a temporary antenna must be erected Most amateurs, who have low-HF mobile rigs, will testify that getting out is a pain in the mike button Antenna efficiencies are simply too poor One factor in this dismal equation is that the vehicle body makes a very poor antenna ground system One could, I suppose, carry a supply of 6- or 8-ft copper-clad steel ground rods, and a 9-lb sledge hammer to drive them into the earth wherever a portable station is needed Somehow, that solution doesn t seem too appealing at this point! Besides, have you ever tried to remove an effective 8-ft ground rod from the ground Forget it, it s too much pain for too little gain A better solution is to provide a counterpoise
GTIN - 12 Encoder In None
Using Barcode encoder for Software Control to generate, create UPC A image in Software applications.
Encoding Bar Code In None
Using Barcode generation for Software Control to generate, create bar code image in Software applications.
488 Mobile, emergency, portable, and marine antennas groundplane, as shown in Fig 25-5 In Fig 25-5A we see the electrical situation and connection, while in Fig 25-5B we see the mechanical scheme for a specific situation: A groundplane consists of two or more (even one helps) quarter-wavelength radials connected to the antenna ground point (ie, where the coaxial cable shield connects to the vehicle body) The radials are made of no 14 wire, so are relatively easy to stow Figure 25-5B shows a workable system that will improve the performance of a mobile rig in stationary situations The mobile antenna uses the normal base mount attached to the rear quarter panel of the car adjacent to the trunk lid An all-metal grounding-type binding post is installed through an extra hole drilled in the base
Create Interleaved 2 Of 5 In None
Using Barcode creator for Software Control to generate, create ANSI/AIM I-2/5 image in Software applications.
Reading EAN13 In Java
Using Barcode scanner for Java Control to read, scan read, scan image in Java applications.
Less than
Recognize Barcode In .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Generate 1D In VB.NET
Using Barcode creator for .NET framework Control to generate, create Linear Barcode image in VS .NET applications.
25-5A Two or more radials improve efficiency of mobile antenna used in a portable Coax to communications transmitter setup Antenna tuner Radials: 4 246 FMHz
Barcode Reader In Java
Using Barcode reader for Java Control to read, scan read, scan image in Java applications.
USS-128 Creator In Java
Using Barcode creation for Java Control to generate, create GTIN - 128 image in Java applications.
Two or more 4 Radials
USS Code 39 Drawer In None
Using Barcode creator for Online Control to generate, create Code 3/9 image in Online applications.
Bar Code Recognizer In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
Antennas for emergency operations 489
4 Mobile antenna
246 FMHz
4 Radials
Insulators
Rope
Ground 25-5B Multiple radials are even better
Whip
Grounding type binding post Base mounting
#14 Radial
Car body Coax to transmitter or tuner
Ground point
25-5C Connection of radials to mobile antenna
490 Mobile, emergency, portable, and marine antennas insulator (see Fig 25-5C) Radials for portable operation are attached at this point Although the binding post is small, it easily accommodates two no 14 radials The owner used the vehicle for camping, and the radials were used to improve antenna efficiency I don t believe the dramatic accounts enthusiastically reported by the owner of the car, but my own Field Day experience (and the testimony of the Sudanese missionary doctor) lead me to expect considerable improvement over the unaided loaded whip A potential solution to the inefficiency problem is to replace the mobile antenna with a more efficient, but stowable, antenna that can be brought out and erected when needed One candidate is a surplus military HF whip antenna Intended for jeeps and communications trucks, these antenna/tuner combinations are collapsible and are as efficient as any on the market Although my Alaskan friend could use such a surplus find, my Sudanese friend could not He told me that Americans in the boonies, even (perhaps especially) missionaries, are always suspected by pinheaded local authorities of being agents of the dreaded Cuban Invasion Authority Showing up out there with obviously military radio equipment serves only to seal that belief! The common dipole is often looked down upon by the owners of massive array antennas, but those old-fashioned antennas are capable of turning in some impressive results The dipole is made by connecting two quarter-wavelength pieces of wire to a coaxial-cable transmission line One length is connected to the center conductor, and the other is connected to the shield of the coax In a pinch, zip (ie, lamp) cord and twisted pairs of hookup wire will do for a transmission line Figure 25-6 shows the common dipole and the normal equation for determining approximate length The actual length is found by trimming length until the VSWR drops to its lowest point, a nicety that might not seem altogether important in an emergency The ends of the dipole must be supported on trees, masts, or some other elevated structure Unfortunately, mounting points aren t easily found My Sudanese friend doesn t see many trees! Figure 25-7 shows another alternative antenna that works well for portable operation Based on the dipole, this inverted-vee dipole does not require two end supports but rather a single center support The length of each leg is 6 percent longer than for a nominal dipole Because the application is both emergency-related and temporary in nature, we can get away with construction methods that would be unthinkable in more permanent installations
Copyright © OnBarcode.com . All rights reserved.