Mohammad Qudrat-E-Maula

A Corrugated Printed Dipole Antenna With Equal Beamwidths

A corrugated printed dipole antenna with equal beamwidths in the principal planes is proposed, designed, and evaluated. Orthogonal stubs are added to the dipole arms to equalize its radiation patterns. They also reduce the size of the dipole arms. The antenna is designed to operate at 3 GHz, and has dimension of 36 × 80 × 1.58 mm3. The -10 dB S 11 bandwidth of the antenna is from 2.75 to 3.62 GHz, i.e., 27.3%. The E- and H-plane radiation patterns of the antenna are nearly equal up to 135 ° from the boresight. To confirm the simulation results, the antenna is fabricated and tested, showing good agreement between simulation and measurement results. Its performance as a feed on a deep reflector, with f/D = 0.25 and D = 45 cm is also studied, where f is the focal length of the reflector and D is its diameter. It provides an enhanced bandwidth of 29.6%, equal E- and H-plane radiation patterns of the reflector, and a gain of 21.4 dBi or an efficiency of 69%. The reflector is only 4.5 λ0 in diameter and would suffer significant blockage losses with conventional waveguide feeds. The proposed feed causes negligible blockage, and provides a respectable efficiency. It is a suitable feed for small symmetric reflectors.

Dielectric loaded circular waveguide feeds

In this paper, dielectric loaded circular waveguide feeds are designed and investigated for radiation pattern equalization. The small diameter circular waveguide feed has unequal radiation patterns in the principal planes, which are not suitable for prime focus reflectors. To make the pattern equalization, the dielectric rod is used inside the waveguide. It further reduces the overall diameter of the waveguide. The antenna is designed at 10 GHz, with dielectric constant εr = 2.5 and loss tangent 0.002. The numerical result shows that the radiation patterns are symmetrical in the principal planes with 10-dB beamwidths of 126°, cross-polarization level is -27.6 dB, and back lobe level is -31.4 dB, when the dielectric rod is extended by a 0.5 λ0 from the aperture with a rod radius a = 0.3 λ0. The S11 of the antenna is also investigated and it is below -10 dB within the frequency band of 8 to 12 GHz.

Performance of small primary feeds with E- and H-plane slots

In this paper, the performance of small circular waveguide feeds with E- and H-plane slots is investigated. The slots are categorized by small and large slots depending on slot length. It is shown that for small slots, pattern broadening is possible with equal E- and H- plane patterns, at the expense of cross-polarization. For large slots, identical E- and H-plane pattern with pattern broadening is achievable without degrading the cross-polarization. The back lobe level is unaffected for all cases.

Broadband rare radiating printed dipole antenna

This paper presents a broadband microstrip fed printed dipole antenna with back radiation properties. Printed dipole employs a microstrip fed line which simplifies the feeding mechanism of the antenna. By modifying the feed line broadband nature is achieved. A reflector is used to give backward radiation that makes this antenna as a feed for reflector antenna.

Suppressing higher order modes of cavity surrounded stacked microstrip antennas for prime focus reflectors

A cavity surrounded stacked circular patch antenna is investigated as a feed for prime-focus reflectors in this paper. The radiation patterns of this feed are slightly asymmetric in the E-plane, which are improved by a differential feeding technique using two probes. This feed has a bandwidth of 20%, and wide beamwidths which improve the overall efficiency of symmetric parabolic reflector antennas.

A dual band microstrip dipole antenna

This paper presents the simulation and experimental results of a dual band microstrip dipole antenna. The uniqueness of this antenna design is due to its simple structure and feeding mechanism with low manufacturing cost. The antenna is designed at a substrate with εr = 2.5 and height h = 1.58 mm for 3 and 3.5 GHz frequency bands. The -10 dB S11 bandwidths for the first band is from 2.8 to 3.1 GHz and for the second band is from 3.45 GHz to 3.61 GHz. The radiation patterns at these frequency bands are good with low cross-polarization and back lobe levels. To confirm the simulation results, the antenna is also fabricated and experimentally tested in the laboratory. The simulated and measured results agree with each other.

Size reduction of a rear radiating microstrip fed printed dipole antenna

A miniaturized rear radiating printed dipole antenna is presented. The length of a dipole antenna is typically λ/2. By loading slits on the dipole arms, the electrical length is increased and the physical length is decreased for a specific frequency. Designs based on the dipole arms with a pair of slits have been made to demonstrate this effective technique. For the best designed results, the presented antenna obtains a size reduction of about 60% with a four pair of slits case, compared with the original one.

E-plane slotted circular waveguide feed with a single choke

This paper presents the design and performance of E-plane slotted circular waveguide feed with a single choke. The feed is designed at 10GHz operating frequency that equalizes E- and H-plane radiation patterns with low cross-polarization. The slots width and height are varied to investigate their effects on the output characteristics such as 10-dB beamwidths, cross-plarization and back lobe level. To evaluate the feed, its operation within 10% frequency band is studied and the efficiencies are calculated.

Phase center study of slotted circular waveguide feed

This paper has investigated the location of the phase center of a slotted open-ended circular waveguide feed. The phase centers in the E- and H-planes of the feed are calculated over different aperture angles, corresponding to different f/d ratios of prime focus reflectors. The results are presented in graphical form to provide useful design information and show the dependence of principal E- and H-plane phase center locations on feed parameters.