About High-Gain Handheld Antennas

High-Gain Handheld Antennas
An antenna is an extremely important part of your radio transceiver and should be treated as such. Without it, your signal will suffer and it’s something you shouldn’t skimp on.What you’ll want to look for in a high-gain antenna is its actual gain, which reputable antenna manufacturers will list in the product details. Antenna gain is a measurement of the effect the antenna has on the signal and is expressed in positive decibels (dB), antenna loss is expressed in negative decibels.
Antenna gain is usually defined as the ratio of the power produced by the antenna from a far-field source on the antenna’s beam axis to the power produced by a hypothetical lossless isotropic antenna, which is equally sensitive to signals from all directions. Usually this ratio is expressed in decibels, and these units are referred to as “decibels-isotropic” (dBi). An alternative definition compares the antenna to the power received by a lossless half-wave dipole antenna, in which case the units are written as dBd.Many things can affect antenna performance in the near field region, which refers to objects near the antenna that can positively or negatively impact it. One of the most common things that can affect a handheld can actually be you.
Other things to look for in a high-gain handheld antenna is that it’s dual band capable and covers the frequency and power you’ll be operating on. Here’s an example of how Nagoya lists their NA-771 Dual Band 144/430Mhz U/V SMA-F Antenna. The first part of the description tells you what frequency its operating at (144 Mhz VHF and 430 Mhz UHF) and you’ll also see Dual Band written there along with the type of connection, which in this case is SMA-F (SMA female).
Further in you’ll also see a max power of 10 watts, which is plenty, considering most handhelds max out at 5 watts. The antenna’s gain is listed as “144Mhz 2.15dBi 430Mhz 3.0dBi” which means that in the VHF 2 Meter Band (144 Mhz – 148 Mhz) you’ll get a +2.15 dB gain, which is almost twice the gain of a stock antenna. In the UHF 70-Centimeter Band (430 Mhz – 450 Mhz) you’ll get a +3.0 dB gain, which is exactly twice the gain of a stock antenna.
Just note that an antenna like this isn’t optimized for all the frequencies a radio like the retevis can handle, this antenna I’m using as an example is purely optimized for the 70-Centimeter and 2 Meter Bands, which are are the bands used by local emergency radio services such as the Amateur Radio Emergency Service, Radio Amateur Civil Emergency Service and Community Emergency Response Teams.Nagoya, Diamond and Comet are good names to look for in high-gain antennas when you’re out there researching them.
Relocating High-Gain Antennas
Something you’ll more than likely experience when replacing your stock antenna with a high-gain antenna is the length of your new whip-style antenna getting in the way. There’s a couple of things I can suggest for taming unwieldy antennas.Depending on where you’re running your radio from will determine which of these techniques will be best for you. The simplest option is to run your radio from a backpack or chest rig strap and use a Rigger’s Rubberband to curve the antenna back towards you to reduce it getting in your way. You can always release it from the rubber band if you’re not getting a good signal, but you shouldn’t have to.
This of course might mean the radio itself is in your way though and you want to run it in a pouch on your belt or in a pouch on a chest rig. What you can do at this point is relocate the antenna if you have available MOLLE webbing to do so, or an attachment method to a backpack, etc. All you’ll need for this is an extension cable that’s set up correctly for your antenna attachment. Don’t skimp on the extension cable and ensure you’re buying quality connectors and a name brand cable, an inferior cable can cause a poor signal, no matter how good your antenna is. An extension cable can also attenuate, or reduce the
signal strength and some companies will list how much reduction to expect in dB.
This is a good time to compare SMA connections to BNC connections. I’ve included a photo below describing Male SMA, Female SMA and BNC connectors. This is very important when buying extension cables and antennas in general. You need to know whether the transceiver portion of your radio is SMA or BNC, as well as whether it’s a male or female interface.Another accessory you might want to consider if you’re running a radio from a chest rig or dedicated radio pouch is a right-angle connector. Using a right-angle adapter for your extension cable can prevent your cable from getting crimped as its routed around your equipment. Again, double check your connections to ensure you’re buying the right type of right angle.Many of the same companies I recommended to research for high-gain antennas make dedicated external antennas that either permanently mount on a vehicle, or utilize a magnet mount, making removal easy.

Views: 1627

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top