Antennas for Ultimate LRS

Introduction

Antennas are a very important part of the system. There are many different antennas that can be used, but the first remark is to avoid monopole antennas, especially the ones provided with OrangeRX and Wolfbox modules.

Dipole antennas for TX or RX

Dipole antennas give a good range, and are almost omnidirectional : they just don’t transmit or receive in the antenna axis (along the wire). They can be used vertically or horizontally.

It’s better to place them on the wing or rudder, or at least not too close of the motor, battery and other metallic elements that can ‘hide’ them or affect their radiation pattern. Using a length of coax cable is not an issue, just be sure to use 50 ohms cable.

While it’s possible to use longer dipole antennas, the most common size is the half-wave dipole antenna, where the two parts of the antenna measure each one quarter of the wavelength.

The important point is that the waves don’t travel at the speed of light in a material (copper wire for example), and this must be taken into account for calculating the length.

It’s difficult to find the correct measurements, so I made measurements to determine exactly the length correction to apply, and made a ruler that should be printed without any resizing (uncheck options such as ‘adjust to page’ when printing) :

Dipole antenna ruler

Click to open in pdf format :

ULRS Dipole Antenna Ruler

 

DIY Moxon antenna for TX

rcgroups user jamesgsf proposed a DIY Moxon antenna (see the ULRS thread here) with a good SWR.

moxon

tx station

my paper moxon my paper moxon 2

 

433 Mhz antennas for TX

Yagi antenna with 7 elements, 11.5 dBd, length 70cm

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Yagi antenna with 10 elements, 13 dBi, length 1,20m

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Yagi antenna with 12 elements 14 dBd,  1,10m

2015-10-25 17_31_21-ZL12-70 70cm 12 ELEMENT SPECIAL YAGI ANTENNA - ZL Special Yagi Antenna - Beam an

Yagi antenna with 15 elements, 14.8 dBi, length 2.245m

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Yak-54’s 3 elements DIY Yagi

Link to original post

Yak-54’s 4 elements yagi

Yagi antenna DIY 4 elements

Here’s a small DIY yagi that works fine :

(click here for original site)


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DIY 7 elements 433 MHz Yagi antenna

2014-06-07 22_37_54-445 MHz Yagi Design Details (Metric)

 

DIY 432 MHz Quadruple Quad

Original source : here quadruplequad   Image5

Ground-plane antenna for TX

This one works great (link to order page) :

2015-10-25 21_07_48-Antenne 433 MHz ground plane GP433

Half-wave coaxial dipoleSubmitted by rcgroups user jvargas (link) :

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Ring antenna

ring-antenna img_20161201_155724img_20161201_155615 img_20161201_155601img_20161201_155657

Ringo Omni Antenna

Interesting vertical antenna including a balun which gives it a perfect 50 ohms impedance :

Full datasheet

Link to vendor website

Antenna analyzer

An ULRS user recommends the N1201SA antenna analyzer, pictures here and order page here.

Other DIY Antennas

Check the user-provided content page for other antenna ideas.

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