The difference between UHF and VHF antennae

[bagman002]

Hi Aussie Scanners,

I am new to this forum and forums in general as there are few that I like or that interest me.

I have used CB radios in the past more for recreational use as a kid. As for the setup and installing I am a noob. I just bought myself a cheap programmable radio with the primary use to listen/talk with FireCom and FireGround (I should mention that I am a Rural Fire Fighter so talking will only be when I am with the brigade) as well as listen to local police chatter.

However getting back to the question. Like I mentioned I just bought myself a radio and it came with both a UHF and a VHF antenna. Apart from the size what is the difference? I can talk and transmit using both antennae for both UHF and VHF.

I hope this is not a stupid question but I would like to learn more about radio communication.

Brent

[rochedalescan]

If I were you Brent, I would stick with using the UHF Antenna on the UHF band. It may work with both but you will probably find you will get out alot better with the UHF band antenna as they specifically tuned for that particular band.

VHF for you and I is generally for use on a boat with a VHF boat radio but is sometimes used by those that like to set up amateur band radio (VHF band is from 140-170mhz). UHF is anything from 400mhz upwards of 500mhz which will be the band that Police/Fire are using in your area.

Cheers Shane

[Phil]

Actually it is possible that this antenna could be VHF mid band which the fire and ambos use alot up there


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[bodyguard]

or he grabbed a cheap Chinese radio that has the dual vhf/uhf which would have the right antenna on it

[bagman002]

VHF for you and I is generally for use on a boat with a VHF boat radio but is sometimes used by those that like to set up amateur band radio (VHF band is from 140-170mhz). UHF is anything from 400mhz upwards of 500mhz which will be the band that Police/Fire are using in your area.

Sorry I wasnt quite clear on my question as this doesnt really answer this. I know what frequencies determin HF, UHF and VHF but my question was more in regards to the antenna itself

Just to clarify the only difference is what frequencies they are rated for? Is the build or materials the same?

I am still trying to find out what frequency will work with me for FireCom in my area as the ones listed on this site didnt help me. However as far as I am aware we use VHF for FireGround. The coms that we use between appliances and between crew members

or he grabbed a cheap Chinese radio that has the dual vhf/uhf which would have the right antenna on it

I did buy a cheap radio as you said as this was my first radio purchase I didnt want to spend too much and for the moment it does what I want.

[Comint]

Just to clarify the only difference is what frequencies they are rated for? Is the build or materials the same?

Basically, the "electrical length" of the radiating element determines the frequency an antenna is "rated for". The "build or materials" depends on the design and manufacturer.

Using a VHF antenna on UHF frequencies, or vice versa, can cause serious damage to the output stage of radio transmitters. And on receive, can be detrimental to the quality of received signal.

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Comint

[bagman002]

Comint,

Thank you for that information, I will be sure to swap the antenna from now on

[bodyguard]

do you know its illegal to use other radios apart from QFRS issued stuff on QFRS freqs ?

You have been warned

[bagman002]

do you know its illegal to use other radios apart from QFRS issued stuff on QFRS freqs ?

You have been warned

Thank you for that, No I was not aware of this

[AIRMAN]

Same applies to QPS & QAS

[BradT87]

do you know its illegal to use other radios apart from QFRS issued stuff on QFRS freqs ?

You have been warned

What about other agencies that have access to the network? Say- National Parks fire units.... They aren't using QFRS issued radios on the QFRS network; they are using national parks radios on QFRS VHF & UHF channels.

This seems a logical, however interesting rule.... But I have never heard of it.

[Vkfour]

Under the Radio Communications Act, it is illegal to have any non type approved radio in your possession. Amateur radio operators are exempt this rule as they are allowed to make their own equipment, but can't use them on anything but their own frequencies. Basically, unless the radio has a compliance sticker from the ACMA on it, it is illegal. Don't get caught.

[Comint]

What about other agencies that have access to the network? Say- National Parks fire units.... They aren't using QFRS issued radios on the QFRS network; they are using national parks radios on QFRS VHF & UHF channels.

Basically they operate under a Memorandum of Understanding (MoU), which lays out the conditions under which the Parties may operate on each others frequencies.

The "bottom line" is that large organisations like to know exactly what equipment, and who, is operating on their networks, so that if a radio is causing "problems" then they know who to contact to get the problem rectified.

If "Joe Blow" comes up with his own personal radio, there is no guarantee that the radio is even set-up correctly,
ie., Bandwidth (12.5/25kHz), CTCSS, Repeater Offset, Frequency accuracy, etc. and they have no way of knowing who to contact in the event of "problems".

In general, most of the cheap Chinese radios are illegal in Australia, except for Amateur Radio use, as they aren't "Type approved".

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Comint