Quantcast SWEEPING ANTENNAS

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
5-30 or isolators are required. However, by the use of automatic-level control, the power output of the sweep generator can be maintained relatively constant at the point of measurement. The source impedance may thus be maintained very close to the nominal value. With this arrangement, any impedance variation in the connecting cables, connectors, and adapters is effectively cancelled since these components are within the leveling loop. The attenuation of a device under test will be displayed on the associated crt as a continuous response curve as it is scanned. This will result in an attenuation versus frequency plot of the device under test only. IMPEDANCE Circuit impedance is measured conveniently by using the reflectometer principle. The individual values of the incident and reflected signals (swr) in a transmission line feeding an unknown impedance are measured. The ratio between these signals indicates how closely the load impedance matches that of the transmission line. Another method is the use of an auto-mechanical load control to hold the forward power at a constant level while the return load of a specific load is measured. A short is then placed in the circuit, and 100% reflected power is measured. The loss detected is then calculated to obtain swr figures. NOISE FIGURE By using a frequency-sweeping receiver and an automatic noise-figure meter, you can make noise- figure measurements on broadband microwave devices, such as a traveling-wave-tube amplifier. To conduct such a test properly, you must first check the receiver noise figure. Q-11. In swept-frequency testing the impedance of a transmission line, what electrical characteristic is actually being measured? SWEEPING ANTENNAS Antenna system testing is one of the more common and useful applications for using the swept- frequency technique. The main parameters that an antenna system is tested for are vswr, frequency response, and impedance. Figure 5-31 shows a typical test setup for testing a transmitting antenna for vswr. Remember that any transmitting antenna can also act as a receiving antenna and send induced power from adjacent antennas back to the test equipment. You should make an initial power check on the antenna to prevent damage to your test equipment. Figure 5-32 shows a typical hf transmitting antenna vswr display as measured using the swept-frequency technique. The setup for testing a receiving antenna vswr, shown in figure 5-33, is similar, with the exception of the attenuators. The measured vswr (within the operating frequency range) of any broadband antenna should not exceed a vswr of 2.5 to 1. The vswr for any single-tuned antenna should not exceed 1.5 to 1 at the tuned frequency.


Electrical News
When Is a Subsystem Not Like an IP?
CPU and GPU subsystems are not just "bigger IP" because...
eetimes.com
Microsoft, Opera Partner On Phone Browser
Opera Software's Opera Mini browser will replace Nokia's Xpress on...
eetimes.com
US Military To Launch Open Source Academy
Camp Shelby Joint Forces Training Center in Mississippi will offer...
eetimes.com
iPhone 6 Production Delays May Hurt Availability
Apple's iPhone manufacturing partners are struggling to produce displays for...
eetimes.com
Creating New Faceplates for Antique Analog Meters
If you wish to use antique meters as part of...
eetimes.com
Timing Closure, Trails & Sleep: I Need a Clone!
An engineer grabbles with a design that didn't come with...
eetimes.com
DDR4 LRDIMMs: Ready for Enterprise Memory
Here's a look at the advances the industry has made...
eetimes.com
iPhone 6 Facts – Finally
Top 10 app developer separates fact from rumors about Apple's...
eetimes.com
Vehicle-to-Vehicle: 7 Things to Know About Uncle Sam's Plan
Now that more new cars are equipped with ADAS, the...
eetimes.com
Silicon Valley Builds Bridge to Iran
Serial entrepreneur Kamran Elahian is organizing a Silicon Valley event...
eetimes.com
Friday Quiz: Transmission Lines
Signal integrity evangelist Eric Bogatin makes us think about what...
eetimes.com
EEVblog #655 – Auction Score
Lots of test equipment auction goodness from Precision Mechatronics who...
eevblog.com
EEVblog #656 – Auction Score
Lots of test equipment auction goodness. And is it possible...
eevblog.com
Low-Cost Cabinet Solution for Prototype Systems
Would cabinets made using a custom extrusion technique be good...
eetimes.com
Power Week: IRF Only One of Many Rumored Infineon Targets
Prior to this week's big announcement of Infineon's agreement to...
eetimes.com
Infineon Buys International Rectifier
Infineon Technologies will buy International Rectifier for about $3 billion...
eetimes.com
mCube Forms Indoor Navigation Subsidiary
Fabless chip company mCube has formed Ten Degrees Inc. as...
eetimes.com
EEVblog #654 – Sydney Maker Faire 2014 Behind The Scenes
Behind the scenes at the 2014 Sydney Mini Maker Faire...
eevblog.com
Don't Let Cables Zap You: Run a Hipot Test
Don't install unsafe cables. Make sure they've been hipot tested...
eetimes.com
Mesh Network Key to Winning IoT Race
As competing wireless networking technologies gun for the smart home...
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 +