Quantcast LONG-WIRE ANTENNA

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
4-41 LONG-WIRE ANTENNA A LONG-WIRE ANTENNA is an antenna that is a wavelength or longer at the operating frequency. In general, the gain achieved with long-wire antennas is not as great as the gain obtained from the multielement arrays studied in the previous section. But the long-wire antenna has advantages of its own. The construction of long-wire antennas is simple, both electrically and mechanically, with no particularly critical dimensions or adjustments. The long-wire antenna will work well and give satisfactory gain and directivity over a frequency range up to twice the value for which it was cut. In addition, it will accept power and radiate it efficiently on any frequency for which its overall length is not less than approximately 1/2 wavelength. Another factor is that long-wire antennas have directional patterns that are sharp in both the horizontal and vertical planes. Also, they tend to concentrate the radiation at the low vertical angles. Another type of long-wire antenna is the BEVERAGE ANTENNA, also called a WAVE ANTENNA. It is a horizontal, long-wire antenna designed especially for the reception and transmission of low-frequency, vertically polarized ground waves. It consists of a single wire, two or more wavelengths long, supported 3 to 6 meters above the ground, and terminated in its characteristic impedance, as shown in figure 4-34. Figure 4-34.—Beverage antenna. Q44.   To radiate power efficiently, a long-wire antenna must have what minimum overall length? Q45.   What is another name for the Beverage antenna? V ANTENNA A V ANTENNA is a bi-directional antenna used widely in military and commercial communications. It consists of two conductors arranged to form a V. Each conductor is fed with currents of opposite polarity. The V is formed at such an angle that the main lobes reinforce along the line bisecting the V and make a very effective directional antenna (see figure 4-35). Connecting the two-wire feed line to the apex of the V and exciting the two sides of the V 180 degrees out of phase cause the lobes to add along the line of the bisector and to cancel in other directions, as shown in figure 4-36. The lobes are designated 1, 2, 3, and 4 on leg AA', and 5, 6, 7, and 8 on leg BB'. When the proper angle between AA' and BB' is chosen, lobes 1 and 4 have the same direction and combine with lobes 7 and 6, respectively. This combination of two major lobes from each leg results in the formation of two stronger lobes, which lie along an imaginary line bisecting the enclosed angle. Lobes 2, 3, 5, and 8 tend to cancel each other, as do the smaller lobes, which are approximately at right angles to the wire legs of the V. The resultant waveform pattern is shown at the right of the V antenna in figure 4-36.


Electrical News
Anatomy of an ARM Server Chip
Four out of the top five server IC companies prefer...
eetimes.com
IoT Gives Old Technology New Life
Cypress Semiconductor sees a great deal of potential for SONOS...
eetimes.com
Andes Ready to Rumble in CPU War
With ARM reigning as king of the CPU IP market...
eetimes.com
D-PHY, M-PHY & C-PHY? First Look at Testing MIPI's Latest PHY
One of the significant advantages of MIPI Alliance standards is...
eetimes.com
Homeless in Silicon Valley
Over Labor Day, I thought about the situation for the...
eetimes.com
Wireless Net Takes the Next Train
The first products are about to adopt the new 802.15.4p...
eetimes.com
EEVblog #659 – Medical Plugpack Teardown
What’s inside an IEC60601-1 medical class 5V mains DC-DC plugpack?...
eevblog.com
Ethernet Links Go Green
Everything that uses energy uses too much if it. Energy...
eetimes.com
Android Wear: Where Are the Wares
Here are examples of some of the watches that use...
eetimes.com
Intel Wearables Contest Goes New Age
Emotional prosthetics, modular smartbands and sixth sense necklaces make up...
eetimes.com
EEVblog #658 – Mailbag
Mailbag Monday. Dave opens his mail Spoilers: Keithley 177 Multimeter...
eevblog.com
EEVblog #657 – Maker Faire 2014 Interviews
Some interviews from the 2014 Sydney Mini Maker Faire at...
eevblog.com
The Internet of Things Versus Slumlords
Smart thermostats are not only for the well-to-do. One group...
eetimes.com
IBM Watson Speeds Drug Research
IBM Watson moves from supplying known answers to tough questions...
eetimes.com
Samsung Funds III-V FinFETs in US Lab
Samsung is funding Penn State researchers working to fabricate III-V...
eetimes.com
LG, Samsung Debut Smartwatches, Apple Lurks
LG's G Watch R and Samsung's Gear S do little...
eetimes.com
Imagination Takes On Raspberry Pi
Imagination Technologies has developed its own version of Raspberry Pi,...
eetimes.com
California Smartphone Kill-Switch Law: What It Means
Do you understand the consequences of California's new smartphone anti-theft...
eetimes.com
9 Insights From Hot Interconnects
Facebook described its network switch, while experts picked apart flaws...
eetimes.com
Microchip in Pursuit of CSR
Microchip confirmed Thursday that it has had preliminary mutual discussions...
eetimes.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +