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Do It Yourself (DIY) ANTENNA

How to build and test your own Wi-Fi and WLAN Antenna
LAST UPDATED:   Wednesday 23rd September 2015

Tin Can Feed

    Click on the headings below

Sponsors Links



Standard Wi-Fi or WLAN equipment can be improved by adding "high gain" antenna.

The gain of the antenna at each end of a link multiply together and this table attempts to conservatively indicate how far you can expect to get a FULL SPEED CONNECTION by increasing the "gain" of the antenna used at each end of the link.

Henry O'Tani (G8OTA)

Fof full data to 85km / 53 Miles click on the above table or follow this link: Table 1.htm

- Sept 2015



  NOTES on 802.11 rain attenuation

propagation thru rain.htm

from John Waters


PolarPlot is a program that lets you see what the polar diagram
of your rotatable beam antenna actually looks like where it is operating.
It has been written for the ham radio community interested

in knowing more about their beam antennas. 

You can download and try out PolarPlot to see if you like the look of it.
The program will operate fully for 30 runs during a 15 day period.
You can check that it works on your equipment and take take
a look at some sample antenna plots.  All that is needed (apart
from your rig of course!) to measure your own or someone else's
antenna is a standard PC with a sound card.  For more information
look at this copy of the user guide  PolarPlot runs on
Windows 95/98, Windows/NT4 and Windows 2000,
desktop machines and even laptops!

With PolarPlot you can measure the polar diagram of the antenna
and check for abnormalities - compare plots taken before and after
changes to the design or location - check the -3dB beamwidth -
look at the front to back ratio - see the size and position of the
sidelobes - compare the design pattern to the actual - gain a
better understanding of the antenna. You can view the plot on
a circular or rectangular grid, with either log or linear scales.
The screenshot on the right is a 2m beam before and after a
re-build - the blue is the before, and the red is the after!.
Take a look at some more screenshots of PolarPlot in action. 2m 8el after rebuild.jpg (74658 bytes)

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  G4JNT Microwave Broadband (ATV)
path prediction program for PCs

A set of Public Domain programs for plotting microwave (broadband amateur
television) line of sight radio pathways,using NGR/Locator Grid. Draws Localmaps
around a given point. Point-to-point Terrain paths and optical horizon Views.

Mainland Britain only. MicroSoft DOS or Windows.


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  VE2DBE "RADIO MOBILE" path prediction program for PCs

Radio Mobile Version 3.5.4 Radio Propagation and Virtual Mapping Freeware by

An up-to-date Windows program useable world-wide requiring additional mapping and topographical data obtainable from other external sources.....

Elevation data For most of the world is available

The software also provides 3D views, stereoscopic views, and animation.

Freeware by VE2DBE


Getting started in

"Radio Mobile"

G8GTZ (20/3/2002)

  Getting started in "Radio Mobile"

Radio Mobile is a fantastic program for predicting links and radio coverage. However,
it does take some time to get to know and the user documentation is not the best!
So here is the G8GTZ how to get started guide.

Download in original Word format

Noel - G8GTZ


ONLINE Terrain Plot

(United Kingdom Only)

  Online Terrain Plot U.K.

This page is an online implementation of a program used by UK radio amateurs since 1993.
Credit is due for the original Power Basic design, logic and implementation
due to Andy Talbot G4JNT



Multiple packet capture sources
Runtime network sorting by AP MAC address (bssid)
IP block detection via ARP and DHCP packet dissection
Cisco product detection via CDP
Ethereal and tcpdump compatable file logging
Airsnort-compatable "interesting" (cryptographically weak) logging
Secure SUID behavior
Cloaked network detection
Grouping and custom naming of SSIDs
Multiple clients viewing a single capture stream
Graphical mapping of data
Cross-platform support (handheld linux and BSD)

  Kismet 802.11b Wireless Network Sniffer (Linux Based)

What is it?

Kismet is a 802.11b wireless network sniffer. It is capable of sniffing using almost any

wireless card supported in Linux, including Prism2 based cards supported by the
Wlan-NG project (Linksys, Dlink, Rangelan, etc), cards which support standard packet
capture via libpcap (Cisco), and limited support for cards without RF Monitor support.

Author: Mike Kershaw (



  Net Stumbler is a website dedicated to wireless networking technology and security of
all kinds. We do our best to keep our website up to date with the latest wireless news
- we really appreciate user submitted stories. is also the official home
of the NetStumbler software.

NetStumbler is a Windows utility for 802.11b based wireless network auditing written by
Marius Milner.

March 2004


  SMART ID - WFS-1 WI-FI Detector

It is becoming increasingly difficult not to be caught up in WiFi traffic since so many homes
and businesses are taking advantage of this technology. Unfortunately, the ever-decreasing
prices and ever-improving ease-of-use has also caused wireless networks to be real
security problems within businesses and institutions. At a personal level, it would be
useful to have a way to know where these public "hotspots" are without having to
arry around equipment that makes you look like an extra from a Star Trek set.
At a corporate level, it would be extremely advantageous to have a means to
detect rogue WiFi equipment at all company sites without having to spend many
thousands of dollars on an enterprise-level WLAN detection system.

A solution may be at hand with the appearance of two "pocket-sized" 802.11 detectors
on the market: the Smart ID WFS-1 and the Kensington WiFi Finder. Both devices
claim to detect 802.11b and 802.11b/g traffic and report the strength of the signals.
They each cost in the area of $30 USD. The question is: how well do they work and
how can you use them for both personal information gathering and corporate protection?

Bob Rudis
September 2, 2003

March 2004


  Understanding Antenna Radiation Patterns

Understanding and Using Antenna Radiation Patterns
By Joseph H. Reisert

Each antenna supplier/user has different standards as well as plotting formats.  Each format
has its own pluses and minuses.  Hopefully this technical note will shed some light on
understanding and using antenna radiation patterns.

All antennas have directional qualities.  They do not radiate power equally in all directions. 
Therefore, antenna radiation patterns or plots are a very important tool to both the antenna
designer and the end user.  These plots show a quick picture of the overall antenna response.
However, radiation patterns can be confusing.

March 2004


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  CanTenna - WB8ERJ

I have come up with my own version of the classic "cantenna" using 4 inch diameter
aluminum dryer vent pipe, and a 4 to 6 inch pipe adapter. Although the basic design
is the same as other cantenna type antennas, the materials I ended up using are a
bit different. Preliminary results show a gain of 15 DBi. Not bad for less than $10
worth of materials!

Mike Thompson WB8ERJ

Check out Mike's Web pages:
 My Ham Radio page:

March 2004




We have been experimenting with waveguide antenna, made from old food cans, to
massively extend the range of 802.11b wireless networks. All that was required was fitting,
in the correct place, a driven element consisting of a short piece of copper wire soldered
into the centre of an N-type connector.

One of the antennas made from a J&B whiskey tin.

This was evolved primarily since the Pringle's can antenna. The Pringle's can, being
cardboard, does not last long in a storm, and it is very hard to affix connectors securely.
The dipole-less "yagi" bit inside is fiddly to make, and initial tests show the
waveguide cans to work better.


Dec 2004

  Amateur Antenna #1

This "15 minute antenna" is a quarter-wave ground-plane antenna with trough
reflector formed on the end of 50 ohm coaxial cable with a light sheet metal
trough type of reflector.

(Photo only) Estimated gain >8 dBi

  Amateur Antenna #2

A simple concept, the "circular waveguide antenna" is repeatable & easy to
make with simple tools and without instruments.

These are often calculated and built as efficient amateur dish feeds.
The dimensions given in the example offers 13.5dBi gain... with a
beam-width approximately that required to efficiently illuminate a
standard British satellite dish of f/D ratio = .72)

Radproject 2000


  Amateur Antenna #3

The simple 2.4GHz Double Quad Antenna is a compact and easy to make
high performance antenna offering a theoretical 14 dBi gain. As with the "circular waveguide antenna" type also on this page it offers a beam-width (in the vertical plane) not far off that required to efficiently illuminate a standard
British satellite dish of f/D ratio = .72) The optimum reflector to element
spacing requires a VSWR measurement system for a precise impedance match......


  Amateur Antenna #4

The European "ASTRA" Direct Broadcasting Satellite (DBS) pole mounted
parabolic dish of 60cms dia. with an efficient ("double-quad") feed is capable
of over 25dBi forward gain. Double Quad Feed

In this example the top stub mast is mounted on a standard Amateur Radio
rotator made by Kenwood which motorises through 360 degrees rotation
and the whole mast folds down into a "Rooftop Ski Box" on top of Amateur
Radio vehicle G8OTA/M (mobile RV). (Pictures) double-quad.gif

July 2001


Simple 23cm and 13cm Antenna

(by S51KQ and S53MV)

Please take notice of our Copyright: for commercial use an explicit permission is necessary by the respective author !)
J. Köring, Bahnstraße 3B, 47551 Bedburg-Hau, Germany
Copyright 1999 by
Johannes Köring (DL4EBJ). All Rights Reserved.


2.4GHz Backfire Antenna

  2.4GHz Backfire Antenna

" At the point at which I needed to build an external antenna for my modified Compaq WL100 card I was faced with many options. Internet searches reveal many designs for this band, some of which provide really good homebrew details and others that left a little to the imagination!. I was looking for a design that promised reasonable gain without excessive size. The short backfire antenna is not a common antenna, promised 14dBi and looked easy to build. Several designs were found and analysed which did reveal a few discrepancies which seem now that been resolved."

Click for full size image

Carl Rabe - G6NLC

Dec 2014


Double Quad (Bow Tie)

  Double Quad

* A compact directional antenna useful for workshop and hand-held operation
* Fair gain (14 dBi)
* Wide bandwidth (full 802.11b/g spectrum)
* More compact than Yagi or circular waveguide types of equivalent gain
* Fits a wide range of microwave cooking food containers
* Ideal as a feed to a standard domestic satellite dish
* Liberal mechanical tolerances
* useful as reference antenna
* Easy to replicate
(- but do use correct gauge wire and thickest & best microwave coax you can afford !)
* Can use a 120mm CD as a reflector with slightly diminished performance at 2.4GHz
* Can omit the "Sleeve Balun" for ordinary Wi-Fi use
* Scalable for many frequencies
* See equally practical other variants on this page..

Originally from a German Amateur Radio Microwave Compendium design concept of the
1980's this antenna concept has proven popular for broadband Amateur TV and I have
made examples of these from 600MHz to 6GHz.

It exploits the 6dB gain from solid plane reflector (not everyone knows that ! )

Henry - G8OTA double-quad.gif

March 2008


DIY 2.4GHz Yagi Antenna


Easy to Build WIFI 2.4GHz Yagi Antenna

"This antenna will extend the range of your WiFi or 2.4GHz devices (like surveillance cameras) into many miles and kilometers. A yagi antenna is basically a telescope for radio waves. I tired the pringle can antenna and the Yagi beats it hands down in performance."

Dec 2014



A printed circuit 12 dBi version of the Double Quad,
house in an ABS plastic case.

The AntCaptenna (ACA) was born from a desire to make
an antenna that could be used as a 'client' antenna
(i.e. used to connect to an AP) - had a reasonable
gain (12-14 dBi) - was waterproof - was rugged
- could be pole-mounted. The result was the
AntCaptenna - which gets its name from the
Ant-Cap used as the back reflector.

[Ant Caps are used on wooden stumps in Western Australia,
to prevent white ants (termites) from coming up from the
ground into the house.

Rob Clark

May 2003


  Adding an Antenna for DWL-650 PCMCIA card

a short guide to voiding your warranty by: Will Rachelson < will at c0rtex dot com >

The DWL-650

I purchased this card because it was the cheapest (<$100 @ CompUSA). I knew that
I was going to build an antenna, but wanted to do so very cheaply. The connectors
for the Lucent cards are costly and hard to find. There were some nice pictures at
seattlewireless that convinced me it would be easy to add an antenna.

  Use a Surplus Primestar Dish as an IEEE 802.11
Wireless Networking Antenna

High gain from a simple DIY project. Uses a circular waveguide feed for
illuminating a surplus Direct Broadcast Satellite (DBS) dish made here
from a juice can and co-axial connector.....The author notes that the
optimum length should be between 14 and 21 inches with the (can)
opening at the focus of the dish. see Amateur Antenna #2 above

  Bi Quad Feed for Primestar Satellite Dish

Author: Trevor Marshall

"That's all there is to it, folks -- you now have a dish with 27-31 dBi of gain
and negligable sidelobe radiation (<40dB). The beamwidth is about 4 degrees."

see below: WLAN Slotted Waveguide Antennas by the same authorTrevAuor


Central States VHF Society

Antenna Test Reports

  Central States VHF Society - USA

The Central States VHF Society has conducted Antenna Gain
Measurements since its inception in 1967.

The published results can be used to make comparisons

between commercial and homebrew antennas, between different
homebrew designs, and between different commercial designs.

Comparisons can be made between antennas measured in different
years on the 50 MHz through 432 MHz bands because the same
reference antennas have been in use for over 10 years!

Nov 2004



  Design of a Planar Omnidirectional Antenna

Randy Bancroft and Blaine Bateman

March 2004



A 6dBi Vertical Polarised Omnidirectional Antenna

An easy step-by-step guide go making a homemade wireless antenna, for a fraction
of the cost of commercial antenna. Uses readily available parts, and requires no
specialist tools or knowledge.Or in geek speak - an omnidirectional colinear
dipole design suitable for wifi compatible hardware with external antenna connector.

Oct 2003



Double Quad type satellite dish feed design...

The Satenna is a complete unit: 65cm satellite TV dish, plus SatCap.
The combined gain is 29 dBi.

You can make your own Satenna by simply buying or building a SatCap,
and combining with a locally purchased satellite TV dish. Search your
local 'Yellow Pages' for satellite TV installers for good prices
on dishes and roof mounts.

Rob Clark

May 2003


Co-linear Array

  Vertical Co-axial Sleeve Co-linear Array

A vertically polarised omnidirectional co-linear sleeve dipole array consisting of a number of stacked omni-directional elements.

with about 9dBi gain as shown.....

Radproject 2000


  Vertically Polarised 6dBi Co-Linear

You have seen them in catalogs for $150 to $250. Now you can build one for a
fraction of the cost at the expense of some time. Construction time can take as
little as a few days up to a few weeks, depending on your drive and resourcefulness.
Proper acquisition of materials and the tools at your disposal will speed up the
construction time. We will go over some theory, tools and materials required,
construction steps for the feeble minded, installation tips, and our actual
measured results. Construction of an assembly jig will also be covered for
those that wish to mass produce a few of these for your community users.
Everyone will need at lease one of these units for the multipoint location.
Also for those who desire to provide access to a geographic location outside
of their immediate locality.

The collinear antenna was historically used by repeater sites, stacking various
1/2 wave dipole elements on top of each other for increased gain connected by
some equipment to correct for phase error between the elements of the array.
The higher in frequency the better in gain you can achieve in a relatively small
assembly. The eight (8) element array we build here will yield 6dBi gain in a
radome of less than a meter.


Backfire Antenna

  Wlan antenna 2.4 GHz Do-It-Yourself

"My antenna has found been about 2 dB better gain than the Freedom antenna,
which is specificated as 12 dBi antenna."

( This >14dBi measured gain should make a good dish feed for an Ex-Astra European
Satellite Dish.)

11 July 2001

Martti Palomaki


Circular Polarised
Directional Antenna


Circular Polarised Helical Directional Antenna

A high performance circularly polarised directional antenna with a
calculated gain of 18.2 dBi. Similar in concept to the Jason Hecker
design also on this page..

W0OQC Feb 1998

  The "Truth" About Horizontally Polarized Omni-Directional Antennas

There are about 5,000 different antenna designs in existence.
Of those 5,000 designs, horizontal omnis seem to be the one design
most shrouded in mystery in the amateur radio world. UHF applications
requiring horizontally polarized omni-directional antennas usually use
an Alford Slot, its cousin the Rib-Cage Slot, or a loop antenna.
Unfortunately, technical references containing slot antenna information
rarely contain practical design information required to build such
antennas reliably, and few experimenters have access to the
resources needed to fully analyze the radiation properties of their
antennas over wide bandwidths. A low VSWR is often mistaken as
meaning an antenna is functioning well. However, VSWR means
nothing when it comes to radiation patterns and antenna gain.

  Measured Performance Of The WB0QCD Alford-Slot Antenna

You've seen the ads. "5.6dBd gain...flat VSWR and good gain bandwidth
performance over the entire 420-440 MHz band"... But just how well does
the WB0QCD antenna perform in real life? We put ours to the test on a
professional antenna range and the results we found were less than

First, the good news. The WB0QCD Alford-Slot antenna is a mechanically
solid antenna that does exhibit a horizontally polarized, omni-directional
radiation pattern. The E-plane pattern is consistant with that of a single
axially slotted cylindrical antenna with a small diameter/wavelength ratio
(see G. Sinclair, "Patterns of Slotted-Cylinder Antennas"
Proceedings of the IRE, vol. 36, pp.1487-1492; December, 1948).
The antenna is about 3 dB more responsive in the direction of the slot
than it is off the rear of the antenna. This feature is consistant across the
entire 420 MHz to 450 MHz band.


  How to Make a Simple 2.425GHz Helical 
Aerial for Wireless ISM Band Devices

A comprehensive and well written DIY constructional article from Australia
on making a 2.4GHz antenna with about a x 8 range magnification factor.......

(excellent case study example) 

Jason Hecker


  Improved Helical Antenna Design for 802.11b WLAN
- by PA0HOO

The Disappointment
It was very disappointing to find out that 'the thingy' we made wasn't

performing at all. Even the relatively small distance of 200 m could not
be bridged. What was it that we did wrong??.

The dimension were OK, all sizes were according to the known formulas.
The proven calculating programs such as helix_20 from  Holger Granholm
and ‘HelixCalc’ from Jason Hecker gave similar dimensions.

The Experiment
We tried to find out the real 'over the ether' behavior of the antennas over

a wide spectrum. We could use a cable TV spectrum analyzer up to 4 GHz
and tracking generator up to 2450 MHz. Test area: our living room... 
We were astonished to discover that the antennas were radiating very

well around 1650 MHz. 2450 was just outside the band pass.
See the 'test set up' and the graph below. 

Detailed examination of the antenna design 

Looking into detail, there IS a difference between de ordinary Helix antenna
and the PVC-one: The classical helix is al 'on air' spiral,  our spiral is 'on PVC'. 
Kraus' formulas, calculate air spirals.
As our spiral is on PVC, it COULD be that the traveling velocity of the radio
waves inside the antenna is being influenced because of the high er
of PVC. (similar to the cause of shortening factor of coax cables). In that
case Klaus' formulas will give erroneous results. 

Detailed examination of the antenna design 

Looking into detail, there IS a difference between de ordinary Helix antenna
and the PVC-one: The classical helix is al 'on air' spiral,  our spiral is 'on PVC'. 
Kraus' formulas, calculate air spirals. As our spiral is on PVC, it COULD
be that the traveling velocity of the radio waves inside the antenna is
being influenced because of the high er of PVC. (similar to the
cause of shortening factor of coax cables). In that case Klaus' formulas
will give erroneous results. 

The main question is, could our PVC plumber tube actually cause the
working frequency being decreased? If the answer is 'yes', it must be
possible to improve the design. 

Study books say that the  traveling velocity is reversed proportional with
the square root of the dielectric constant.

It appears that PVC has a fairly high dielectric constant.

Jan 2003



.....some inexpensive antenna, radio, and computer interface hardware which
allows communication of digital data at rates up to 2 megabaud
(1 megabaud = 1 million bits per second) on an Amateur Radio band.
The link operates in the 10-GHz Amateur band and uses an inexpensive
commercial parabolic antenna along with a Doppler radar transceiver
module to provide medium range communications at low cost.
We'll discuss modifications to surplus networking interface cards
that let you use this high speed data in Amateur Radio service with
IBM-style personal computers. AX.25 packet radio has suggested the
need for faster systems to improve current performance and has
spawned some fundamentally new ideas for Amateur Radio.

A whole spectrum of new user applications and the possibility of a nationwide or even worldwide digital Amateur network are two major areas made possible by faster hardware. 

Originally published in Ham Radio Magazine December 1989

(A great case study - applicable to current 100Mb and 1Gb DIY link development)


Purdue University Group Project

  Purdue University - 2.45 GHz Yagi Antenna - Lafayette Indiana USA

Useful project to design a directional disc Yagi of17.5dB gain for

point to point WLAN applications.....

Has anyone a current link to this excellent project? ed.

Purdue University:

November 2004

Wireless Internet Access in Latvia

Guntis Barzdins
Institute of mathematics and Computer Science, University of Latvia

Rainis blvd.29, Riga LV1459, LATVIA
Phone +371 9206943, Fax +371 7 820153, E-mail


The Latvian Research Network LATNET was established in
1992, shortly after breaking of the USSR. The limited
resources and poor communications infrastructure in
the country (only analogue lines available) have forced
LATNET to search for alternative ways to establish high
speed data links for Internet access to the numerous
University of Latvia departments scattered around the
capital city Riga. The liberal radio frequency licensing
policy and newly appeared inexpensive and easy to
use wireless LAN products, made it possible to develop
a high speed spread spectrum wireless Internet access
network. There are currently over 30 academic, research,
government, and other sites - spread all over the city -
using these high-speed wireless links for Internet
connection as an alternative to lower speed leased
telephone lines.

Guntis Barzdins

Image of 38.jpg   WinProp

Prediction of wave propagation in indoor, urban and terrain scenarios.
Wireless mobile communication networks incl. Radio network planning
for macrocells, microcells, WLAN, indoor, Picocells.

  WLAN Slotted Waveguide Antennas

Unlike wideband antennas like the BiQuad, slotted waveguides are resonant antennas,
and have a narrow operating frequency range. It is possible to increase the bandwidth,
but at the expense of gain and radiation pattern. Highest gains are only achieved over
a few channels of the 802.11b spectrum. This should not be a limitation in a fixed
installation, as multiple antennas are typically deployed, each covering a few channels.
The antenna can be "tuned" with adjusting screws, or by adjusting its length.
(if you need wide bandwidth then
the BiQuad is the better choice)

Author: Trevor Marshall

see above: Bi Quad Feed for Primestar Satellite Dish by the same author

  Downpipe Antenna

Slotted Waveguide type for 11 -14dBi horizontal polarisation...

The downpipe antenna was born after seeing the success of the
Trevor Marshall Waveguide (WG) design, but after frustration at
trying to buy 'small' lengths of the required ALU tubing, at realistic
prices. In Australia, the minimum quantity is 6 m - you normally need
less than 1 m. A 6m length will not fit in a car, and costs AU$160.

However, 95 x 45 x 0.4 mm ZincAlum downpipe is readily available
in any Australian hardware store, and a 1.8m length costs less than AU$ 9.
While this material is much more 'flimsy', it turned out sufficiently strong
enough that it did not distort when the slots were machined
(my main concern), and was plenty robust enough to mount solidly
with V-Clamps. The material itself is designed to be used outside
- so corrosion is expected to be minimal.

Rob Clark

May 2003

  Horizontal Polarized - Wide-sector directional antenna.

A typical amateur constructed high performance wide sector directional
antenna based on a slotted waveguide design by DL4EBJ

USB adaptors
& DIY antennae

"Poor Man's WiFi" ?

  USB adaptors & DIY antennae "Poor Man's WiFi" ?

Harbour 10Km Link

A popular site with lots of imaginative and interesting low cost antenna ideas for

DIY antenna from Massey University New Zealand.... Frying pans, Cooking Woks,
foil and mesh lined Umbrellas.

"Gains typically ~12-15db with LOS ranges ~3-5km, AND great cost benefits
from using cheap RF loss free USB cable" (repeater cables every 5metres length)

Stan Swan
Wellington, New Zealand

Oct 2005



What is Wi-Spy™?

Wi-Spy™ is the world's smallest 2.4 GHz spectrum analyzer*. Wi-Spy is
perfect for troubleshooting interference from the following devices:

  • Wi-Fi (802.11 b/g/n)
  • Microwave Ovens
  • Cordless Phones
  • Baby Monitors
  • Bluetooth

Wi-Spy is a fraction of the cost of traditional spectrum analyzers!
*Wi-Spy's frequency range is 2.400 - 2.483 GHz


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500mW Booster

  Pen WLAN Booster

WLAN & Wi-Fi 802.11 b/g Booster( Indoor/Outdoor)

500mW PEN BOOSTER 2.4G + Panel 12dBi Pro Base 3M

500mW Indoor PENBOOSTER with RPTNC to RPSMA adapter + 2.4G
Panel 12dBi antenna with LLC200/ 3M RSMA cable + Pro Base

Dec 2010

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