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Topic: Electronically-tunable antenna for software-defined radio (SDR) (Read 4731 times) previous topic - next topic


May 14, 2014, 02:19 pm Last Edit: May 19, 2014, 02:23 pm by Transceive Reason: 1
Hi there,

Antennas are a key enabling technology for software-defined radio (SDR). Although software is extremely flexible, the SDR's potential can be limited by antenna size and design.

We have an SDR antenna shield for Arduino that will help improve your receiver's selectivity.

The antenna can be used in conjunction with SDRs like
the Ettus/NI USRP,
the FlexRadio,
the FUNcube Dongle,
the HackRF
and the RTL-SDR.

The SDR antenna consists of a low-profile electronically-tunable electrically-small slot antenna, which allows for improved receiver selectivity. It covers the cellular 2G/3G/4G bands (LTE-TDD bands not included) and the 2.45 GHz ISM band used by WLAN (IEEE 802.11a/b/g/n) and WPAN (Bluetooth, ZigBee) connectivity standards.

The radiating frequency can be programmed using three analog (PWM) outputs of a micro-controller board, such as the Arduino Uno (C code included). The SDR antenna allows for antenna mismatch characterization in case of head proximity or death grip and MIMO (requires more than one antenna) channel link measurements in fading-induced multi-path environments.

Preliminary specifications (50 ? and 75 ? version):
- Bandwidth (tunable): 700 MHz - 2.45 GHz
- Connector: 50 ? U.FL connector (With a U.FL to SMA adapter for the Ettus/NI USRP, HackRF), or 75 ? F-connector for the RTL-SDR (RTL2832U/Elonics E4000/Raphael Micro R820T)
- Polarization: linear; the cross-polarization at boresight is minimal for fundamental resonant frequencies (700 MHz - 1.225 MHz) due to cross-polarization cancellation.
- Front-to-back ratio: 1:1
- Gain: half-wave length radiators have a gain of 10*log10(?) = 5 dBi. The gain of the electrically-small antenna is slightly less (0-3 dBi) and frequency-dependent.
- Impedance: matched to 50 ? or 75 ?
- Programming: Arduino sketch, GNU Radio
- Size: uniplanar electrically-small antenna (8 by 8 cm). It is much smaller than UWB antennas, such as the discone and Archimedian spiral.
- Tunable elements: 3 RF varactor diodes



Show the schematics..
Bandwidth: 700 MHz - 2.45 GHz

Tunable elements: 3 RF varactor diodes

Do you mean "Tunable range 700 MHz - 2.45 GHz" ??


Dear Pito,

Yes, the tunable range is 700MHz and 2.45GHz.


Bandwidth (tunable): 700 MHz - 2.45 GHz

Is the BW=1.75Ghz, or is the antenna tunable 0.7-2.45GHz? What is the BW then (when tunable)?


Hi Pito,

sorry for the late reply. The antenna is tunable from 0.7 - 2.45GHz. The BW will change depending on the frequency, but it's around 60MHz at the ends of the tunable range, and 100MHz in the middle of the tuning range.

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