5 Antenna Terms You Need to Know

There is a lot of complex terminology in the field of antennas. It's a field that takes a lot of technical understanding and know-how to execute. Although many of you are experts we thought we'd take the opportunity to explain some of the complex terms we refer to in our specification sheets to assist you to better explain them to your customers. 

Our ZCG antennas are made at our Lindenow factory and are tested to ensure they work efficiently in the areas listed below so you receive a piece of equipment made to precise specifications.

Impedance matching
For efficient transfer of energy, impedance matching is required. This impedance matching is completed so as to help the antenna radiate out the signal more efficiently. At ZCG the use of coaxial stubs or altering the size and length of an item will change the impedance and better match it to the required impedance of either 75 Ohms or 50 Ohms. 

VSWR and Reflected Power
The Voltage Standing Wave Ratio (VSWR) is an indication of how good the impedance match is. A high VSWR is unacceptable, the smaller the VSWR, the more efficient the antenna is radiating. 

Most antennas are specified to be 1.5:1 or less but all broadcast antennas must be 1.2:1 VSWR.

Bandwidth
The bandwidth of an antenna is the section of the frequency band where the antenna is performing at the specified VSWR (e.g. 1.2:1 VSWR if broadcast). Depending on the type of antenna, the bandwidth may be narrow or wide. 

Gain
Gain is the amount of "pushing" power an antenna has. Basically, the more elements an antenna has, the more direct pushing power it will have, i.e. a yagi with 15 elements will have more pushing power than a yagi with 3 elements in the desired direction. 

Gain can also be achieved by stacking antennas in a bay array configuration. Being installed in an array enables the antennas to work together to squash the pattern/signal down to "push it" efficiently in the direction it needs to go. 

Pattern
Antennas come in various pattern types, depending on the application.

Omnidirectional antennas push the signal out in a perfectly circular pattern.
Directional antennas focus the signal energy in a particular direction. Wherever the antenna is pointing is where a high percentage of the signal/power is directed. The more elements in a directional antenna, the higher the percentage of energy that is directed.

Antenna polarisation, put simply, is the direction that the elements are laying in relation to the ground. Some antennas can only be mounted in one polarisation due to design and mounting capabilities. however some antennas can be mounted horizontally or vertically due to their design. 

Another crucial factor in the antenna performance is placement.

At the basic level, an antenna is a piece of metal that is used to turn an electrical signal into an RF signal and transmit it into the air or to turn an RF signal into an electrical signal to receive.

All metal objects can be used as an antenna, even a trusty coat hanger can be used as an inefficient car aerial although ZCG don’t recommend it! However for efficient performance of precision equipment, careful placement is required.
 
An antenna mounted on the roof of a car will perform better than the same antenna mounted on the bonnet or boot of a car. In this example, knowledge of the vehicle may also be an important factor in determining what type of antenna to use. You do not want to install a glass-mount antenna on the rear window of a vehicle in which metal has been used to tint the glass or where heating elements are located within the glass. The metal tinting/elements will act as a shield, preventing the signals from passing through the glass. 

Best practice for antenna placement is clear from any other metallic objects, away from any other transmitting/receiving antennas and as high as it can possibly and safely be installed.  

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Portable Antennas and Flexible Whips for Hand Held Radios,
Antenna Bases and Data Devices

ZCG Scalar can supply a variety of stubby whips to fit portable hand held radios, antenna bases and other data link devices. Whips are available for VHF, UHF and Mobile Phone frequencies.

Mount ferrule options include BNC male, SMA male, SMA female, FME female and any base with 5/16"-26 TPI female thread.

Most portable radio whips are factory tuned for a designated bandwidth and therefore can be fitted and used immediately.

However, other stubby antennas are supplied uncut and will require tuning in the field to the desired frequency using an SWR and Power Meter.

Click here to find out more.

If you happen to require portable antennas for a specific frequency range not listed, or with some other type of connector, then please contact us and we will consider custom solutions especially for you.

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If you have any questions about the products in this newsletter, or any of ZCG's products please contact us today:
Head Office, Victoria: [email protected]
Western Australia: [email protected]
Queensland: [email protected]

Or call one of your local sales team direct:
Victoria (03) 5157 1203
Queensland (07) 3800 1204
Western Australia (08) 6253 8950