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
The Top 8 iPad Games of All Time
Considering the fact that Max claims to not be a...
eetimes.com
Industrial Control This Week
Here's a quick look at industrial control news bits this...
eetimes.com
LG, Sony Disclose Smartwatch Details
LG offers more info about its upcoming Android Wear device,...
eetimes.com
The USB Keys in the Urinal
Sometimes it's the people on the inside, not the outside,...
eetimes.com
The USB Keys in the Urinal
Sometimes it's the people on the inside, not the outside,...
eetimes.com
Cadence Breaks Into Top 4 in Semi IP Core Ranking
ARM Holdings remains the No. 1 semiconductor IP core supplier...
eetimes.com
Ultracapacitor Breakthrough May Recharge Energy Storage
A better material for ultracapacitors is a hybrid composite of...
eetimes.com
Slimming ICs to a Single Molecule Wide
Conductors with a layer of built-in insulation are helping chip...
eetimes.com
No-Poaching Settlement Could Spur Tech Talent War
Adobe, Apple, Google, and Intel reportedly close to settling a...
eetimes.com
The Death of the Smartphone
Carrying four devices -- PC, smartphone, tablet, and wearable --...
eetimes.com
Electronics Flea Market Has More Than Electronics
The "Flea at MIT" is a monthly swapfest where you...
eetimes.com
Apple v. Samsung: Google Agreed to Indemnify Samsung
Google agreed to indemnify Samsung against some of Apple's claims...
eetimes.com
IoT Comms Software Is Hard
It's no easy feat tailoring a communications software stack for...
eetimes.com
10nm Process Described in June
IBM, GlobalFoundries, Samsung, and others will describe work on a...
eetimes.com
Can China Mobile Outpace 'Free' Mobile Apps?
Skype's co-founder once predicted that telephones would eventually become just...
eetimes.com
Pointers, Functions, Pointers to Functions, Eeek!
Max is wearing his sad face, because he cannot wrap...
eetimes.com
Altera's FPGA DSP Goes Hardcore
Having hardened floating-point DSP blocks in FPGAs opens the door...
eetimes.com
Scale-Out Storage Has Limits
Disk may scale as your storage needs increase, but what...
eetimes.com
Startup Makes First MEMS Bio-Tag Sales
Bluechiip, an Australian startup, has started selling its own passive...
eetimes.com
Max's BADASS Display, Part 4
Before Max actually starts to create the front panel for...
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 +